For nearly sixty years, the Autism Research Institute (ARI) has tried to understand autism by looking beyond surface behaviors and asking deeper biological questions. From the beginning, Bernard Rimland challenged the dominant view of autism as a purely psychological condition and argued that biology mattered (Rimland, 1964). That position was not widely accepted at the time, but history has proven it correct. Over the years, ARI expanded this biological focus to include genetics, nutrition, immune function, metabolism, and environmental exposures (Edelson, 2017, 2025a). The consistent message has been that autism does not arise from a single contributor, but from the interaction of multiple biological systems with the environment.

One of the lessons learned over decades of research is that some of the most important influences are also the easiest to miss. They are small, commonplace, and part of everyday life. In a previous editorial, Invisible Threats: The Role of Environmental Toxins in Autism, I discussed how environmental exposures often remain underappreciated precisely because they are so familiar (Edelson, 2025b). Air pollution falls squarely into this category.

ARI began paying attention to environmental factors long before large population studies were available. Early on, Rimland, Sidney Baker, Jon Pangborn, and others noticed patterns in parent reports and clinical observations that pointed toward immune dysregulation, metabolic burden, and environmental toxic load. These early efforts were not definitive, but they were consistent. Over time, many of the questions raised in those early years have become the subject of formal epidemiological and biological research (Goodrich et al., 2024; Masi et al., 2017; Oliveira et al., 2005).

In this editorial, I focus on particulate matter, commonly referred to as PM. Particulate matter is a mixture of solid particles and liquid droplets, much of it produced by vehicle exhaust and other combustion sources. These particles range widely in size. Larger particles are heavy enough to fall out of the air within seconds or minutes and deposit on surfaces or in the upper airways. Smaller particles, including PM_2.5 and ultrafine particles (<2.5), can remain suspended for hours or days and travel long distances.

Most people think of air pollution only when it is visible, as haze or smog on certain days. But particulate matter is present even when the air appears clear. It settles on cars and sidewalks, and more importantly, it is inhaled continuously. Exposure is not occasional. It is daily, and for many people, unavoidable.

Because this exposure is constant and its effects are not immediately obvious, PM is often dismissed as background noise. Yet decades of research have established its role in heart and lung disease (see review Hamanaka & Mutlu, 2018). Only more recently has attention turned to its possible effects on other conditions (see review Brockmeyer & D’Angiulli, 2016).

A growing number of studies from different countries now show associations between air pollution exposure and increased likelihood of increased brain-related disorders such as autism, Alzheimer’s disease, and dementia, particularly when exposure occurs before birth or early in life. From an ARI perspective, this trajectory is familiar. Initial observations raise concerns. Early studies provide signals. Over time, evidence accumulates across disciplines. That is exactly what has happened with particulate matter.

How PM enters the body

Two factors are especially important: particle size and toxicity. Particle size affects how easily particulate matter enters the body and reaches organs such as the lungs, cardiovascular system, and brain. Toxicity depends on chemical composition, and particles of the same size can produce very different immune and long-term biological effects. Ultrafine particles, produced largely by vehicle exhaust, particularly diesel emissions, are generally the most chemically reactive and inflammatory. Larger particles from sources such as wildfires and industrial emissions are typically less reactive but can still be harmful with chronic exposure.

Several studies have examined how fine particulate matter may affect the central nervous system (Ishihara et a., 2025). Although air pollution has long been associated with respiratory and cardiovascular conditions, increasing attention is now being directed toward its potential neurological effects. Toxic components such as metals, microplastics, and organic compounds can, under certain conditions, move beyond the lungs and enter systemic circulation. Ultrafine particles may also reach the brain directly through the olfactory pathway or indirectly by influencing the integrity of the blood-brain barrier.

Experimental and epidemiological findings suggest that chronic exposure is associated with neuroinflammation, oxidative stress, and altered neural function. Over time, these biological responses have been linked in population studies to a higher likelihood of neurological conditions, including autism, Alzheimer’s disease, and dementia. Clarifying the specific biological pathways involved remains essential for understanding how environmental exposures may influence brain development and long-term neurological health.

Particulate matter is often treated as a single exposure, but it is not. The same PM level can reflect very different mixtures depending on the source, such as traffic, wildfire smoke, industrial combustion, or even suspended dust. These differences matter because chemical composition strongly influences biological impact. Combustion-related and ultrafine particles are generally more chemically reactive, more inflammatory, and more likely to carry toxic compounds on their surfaces.

Over the past decade, gene expression profiling studies have helped clarify how PM affects biological systems. Despite differences in exposure conditions and PM sources, studies consistently report alterations in pathways involved in detoxification, inflammation, and oxidative stress. Findings from both animal and human exposure studies show similar patterns (Huang, 2013). Together, this evidence indicates that PM exposure can trigger coordinated changes in gene expression that influence immune and metabolic pathways.

PM and autism

Reports of altered detoxification pathways, chronic inflammation, and oxidative stress are not new to autism research. For decades, ARI has monitored patterns of immune activation and metabolic imbalance as a recurring theme. What is emerging more clearly now is the recognition that common environmental exposures may interact with these biological systems during critical windows of development, potentially amplifying underlying vulnerabilities (Ishihara et al., 2025; Jung et al., 2024; Wang et al., 2024).

In recent years, numerous studies have linked exposure to air pollution with an increased likelihood of autism. These associations have been reported across multiple regions, including Asia (Chen et al., 2018; Li et al., 2026), Europe (Flanagan et al., 2023; Jin et al., 2024), and North America (Cloutier et al., 2025; Volk et al., 2013). Most of this research has focused on PM_2.5 and other common traffic-related pollutants. As expected in complex human studies, results vary across populations and methodologies, but the overall pattern of findings points in a consistent direction.

As the research has matured, investigators have begun asking more refined questions. Does particle size matter? Are smaller particles more biologically active? Are there specific windows of vulnerability? Recent work, including analyses from the Childhood Autism Risk from Genetics and the Environment study, suggests that exposure to ultrafine particles during early childhood may be particularly relevant (Goodrich et al., 2024).

This shift toward greater precision mirrors the broader evolution of autism research. Early work identifies associations. Later work clarifies timing, mechanisms, and susceptibility. ARI has encouraged this kind of careful progression from the beginning.

How to prepare for PM exposure in early life

Just as pregnant women are advised to avoid alcohol, cigarette smoke, pumping gasoline into their cars, and other toxic exposures, future public health recommendations may also include guidance related to air pollution. Such recommendations, potentially informed by statistical models, could take into account factors such as proximity to major roads or highways, distance from heavy traffic, and even temperature, since particulate matter can remain suspended in the air longer during warmer conditions (Leffel et al., 2025).

For individuals who live in or spend substantial time in high PM environments, protective strategies may begin as early as preconception and continue through pregnancy and early childhood. These strategies could include using air purifiers in the home and workplace, wearing masks outdoors when pollution levels are elevated, and taking additional precautions to reduce exposure during a child’s early years. Other approaches may involve targeted nutritional supplementation aimed at supporting cellular resilience and detoxification pathways.

As discussed in a previous editorial, the P2i program offers a comprehensive training framework for healthcare providers and families preparing for pregnancy or welcoming a new child, with the goal of reducing overall toxic burden. (See www.forump2i.com.)

Continuing ARI’s legacy of careful, pattern-based inquiry

As always, caution is essential. None of the conditions discussed above are caused by any single mechanism. Autism is certainly not caused by any single factor. Many autistic people are happy being autistic and see autism as part of neurodiversity, meaning all brains are different.  Genetics, immune function, metabolism, and environment all play roles. The current research does not suggest that particulate matter causes autism. What it does show is biological plausibility of how pollution is impacting human experience.

ARI has long emphasized that progress in autism research comes from recognizing patterns early and evaluating them carefully over time. The growing evidence linking particulate matter to neurodevelopmental vulnerability fits this pattern. These exposures are widespread, largely invisible, and part of daily life.

As research advances, the most important questions may shift. Rather than asking whether particulate matter matters at all, the focus may need to move to when it matters most, how it interacts with underlying biology, and which individuals are most vulnerable. These differences likely reflect epigenetic and biological variability, since not everyone exposed to particulate matter experiences adverse effects. Addressing these questions aligns closely with ARI’s longstanding mission to integrate research, clinical insight, and real-world relevance.

This editorial is available in PDF format – Download Here
References are available at www.ARRIReferences.org.
This article originally appeared in Autism Research Review International, Vol. 40, No. 1, 2026

As our knowledge about autism continues to evolve, so does our understanding of its root causes. For many years, professionals blamed “refrigerator parents” and prescribed psychoanalytic therapy. Once the psychogenic theory was debunked, genetic research began to dominate autism science. Today, while we know that genes play a significant role in autism, we are beginning to recognize the critical importance of another factor: the environment (Rimland, 1964).

Currently, questions persist about the relative influence of genetics and environment on autism, with many people still viewing it as a purely genetic condition. However, as research findings mount, a clearer picture is forming. It is apparent that in many if not most cases, the condition arises from a complex interplay between genetic susceptibility and environmental influences (Hallmayer et al., 2011). Research increasingly shows that invisible yet potentially harmful substances can have long-lasting impacts on the fetus before birth and in the early stages of life, highlighting the need for us to take meaningful steps to reduce exposure to these substances—especially during crucial formative months in prenatal and early childhood development.

I believe it is time for the autism field to move beyond the vague use of the word “environment” and begin focusing on specific environmental toxins implicated in autism. Identifying and drawing attention to these toxins will help us to guide public policy, develop targeted interventions, and protect future generations of children.

The interplay of genes and environment

When discussing the causes of autism, it is useful to frame the issue in terms of genetic susceptibility and environmental influences.

Genetic susceptibility helps to explain why many individuals exposed to the same environmental toxin may experience little or no effect, while a small portion develop long-term disabilities. It is likely that there is no specific “autism gene,” but rather, a combination of genetic vulnerabilities that increase susceptibility to certain environmental influences. These vulnerabilities may affect systems such as the immune system, which protects the body from foreign substances, and the metabolic system, which affects the body’s ability to detoxify harmful substances.

Environmental risk factors currently implicated by research

Controlled studies on the effects of human exposure to toxins are of course neither ethical nor feasible, and correlational studies can only suggest an association rather than a cause-and-effect relationship. For example, autism appears to be more common in cities than in rural areas; however, this does not necessarily indicate a causal link, as better access to diagnostic services in cities likely accounts for this pattern.

What adds credibility is that many of these risk factors show a distance or dispersion effect. The closer one is to a source—such as pesticides or particulate matter from vehicle exhaust—the higher the risk of autism (Shelton et al., 2014; Volk et al., 2011). In addition, replication by independent research groups in different regions of the country provides relatively strong evidence supporting a possible causal relationship (Becerra et al., 2013; von Ehrenstein et al., 2019).

Environmental toxins that currently are strongly implicated in autism (see Goines & Ashwood, 2013; Landrigan et al., 2012) include:

Air pollutants: particulate matter, nitrogen dioxide, ozone, carbon monoxide
Pesticides: organophosphates, pyrethroids, permethrin, malathion, avermectin
Metals: lead, lithium, mercury, cadmium, aluminum, chromium, arsenic, manganese
Plastics and industrial chemicals: phthalates, bisphenol A, polychlorinated biphenyls (PCBs)

Patterns emerging from well-documented research

In addition to identifying environmental toxins that can alter fetal and early childhood development, it is important to understand the mechanisms by which they cause harm.

We know that when toxins enter the body, their effects depend on several factors, particularly the ability of the immune and metabolic systems to defend against them. In addition, the level of exposure is critical. This includes both the duration and amount of exposure, as well as the timing. For example, there is evidence suggesting that certain adverse neurological events may occur during the second trimester of pregnancy (Bilder, 2019).

Once toxic agents begin circulating in the body, they can trigger several well-documented biological processes linked to autism. These include brain inflammation (Vargus et al., 2005), oxidative stress (a marker of neuroinflammation; Usui et al., 2023), maternal immune activation (Ayoub, 2025; Usui et al., 2023), and disrupted cellular function. Naviaux (2020) has shown that cellular responses to toxins can initiate what is known as the cell danger response, in which the body enters a defensive state that can impair communication between cells.

Interestingly, emerging research indicates that the effects of particulate matter extend to the gut microbiome (Filardo et al., 2022). Exposure to particulate matter has been associated with disruptions in gut microbial balance that are also reported in autism, including reductions in microbial diversity (Fouladi et al., 2020; Kang et al., 2017). Furthermore, decreases in Bacteroidetes and Lactobacillus—both reported in autism—have also been associated with exposure to particulate matter (Li et al., 2023; Strati et al., 2017; Liu et al., 2021; Mihailovich et al., 2024).

Building on this understanding, a major study published earlier this year identified four distinct subtypes of autism (Litman et al., 2025; see ARRI 2025, Vol. 3). One subgroup, termed “broadly affected,” was characterized by severe delays in reaching developmental milestones such as walking and talking, along with pronounced social-communication challenges and marked restrictive and repetitive behaviors. This subtype closely corresponds to what is often referred to as profound or severe autism (Lord et al., 2024). Notably, autism that arises in the context of maternal immune activation during pregnancy—which can be triggered by toxic exposures or infections—is also frequently described as severe or profound (Ellul et al., 2023).

What is very interesting is that both maternal immune activation profiles and de novo mutations were most prevalent in the “broadly affected” group. De novo mutations are not inherited from parents but instead arise spontaneously as errors during cellular replication, often occurring during early embryonic development. Their occurrence can be influenced by factors such as advanced parental age—a well-documented risk for both mothers and fathers (Croen et al., 2007)—as well as environmental exposures that disrupt genomic stability (Pugsley et al., 2022).

This raises an important question: Could many individuals who are severely affected by autism represent cases in which toxic exposures during pregnancy trigger maternal immune activation and simultaneously contribute to the emergence of de novo mutations? Research exploring this possibility is urgently needed, as it may be relevant to more than one-quarter of the autism population (Hughes et al., 2023).

In a related ongoing research project, Judith Miller, a clinical psychologist at the Children’s Hospital of Philadelphia, is conducting a comprehensive study of environmental factors to which individuals are exposed over time. She is leading a multi-year project that integrates genomic and exposomic data (the latter focusing on lifetime exposures to environmental factors) from more than 100,000 children, including about 4,000 autistic children, and links this data to detailed maternal health records. The study incorporates geospatial data on air and water quality, green space access, and a wide range of other environmental exposures to explore how genetic susceptibility and environmental context may interact in autism.

Final thoughts

Can we realistically reduce harmful exposures when they are so deeply tied to economic and political forces? Cleaning up pollution in the air, water, and soil is an enormous undertaking and often prohibitively expensive, but there are many practical and cost-effective steps we can take.

In the near term, the highest priority should be protecting those most vulnerable: pregnant women and very young children. One promising effort in this area is P2i (Preconception to Infancy), a new initiative launched by the Northwest Autism Foundation. This comprehensive program is designed to support couples from the preconception stage through their children’s infancy, with the goal of promoting safer pregnancies and fostering healthier early development. One of the key goals of P2i is to reduce the body burden of toxic chemicals in mothers and their children.

There is also growing interest in interventions to reduce the harmful effects of environmental toxic exposures in autism. Strategies focus on enhancing detoxification pathways, such as increasing glutathione synthesis and strengthening antioxidant defenses. Additional approaches that support mitochondrial function, lower oxidative stress, and modulate immune responses may further reduce toxicant burden and its neurodevelopmental impact (see Rossignol & Frye, 2012).

Given the importance of efforts such as these, I believe it is time for the autism field to speak more openly and directly about specific environmental toxins and exposures. Greater transparency about these risk factors—such as exposure to certain heavy metals, pesticides, air pollutants, and prenatal stressors—will foster better public understanding and help guide prevention and policy efforts.

Researchers and clinicians have a responsibility to communicate emerging evidence clearly and without unnecessary delay. Open dialogue among scientists, policymakers, and the public will accelerate progress toward reducing harmful exposures and improving outcomes for future generations.

Stephen M. Edelson, Ph.D.
Executive Director, Autism Research Institute

References available at www.ARRIReferences.org.

This editorial is available in PDF format – Download Here
It originally appeared in Autism Research Review International, Vol. 39, No. 4, 2025

Kelly Barnhill, MBA, CN, CCN, discusses nutrition in autism based on recent publications. She outlines research updates on amino acid patterns, probiotics, and dietary interventions, underscoring both what we know and what we don’t know. The speaker discusses the clinical interpretation and application of this research, touching on common nutrient deficiencies before the Q&A.

In this webinar:

0:00 – Introductions
2:00 – Prospective study on amino acid patterns
5:50 – Prospective Study on Probiotic Intervention
7:40 – Systematic Review of Dietary Intervention and Gut Health
10:54 – Bibliometric Analysis of Influential Articles
13:47 – Systematic Review of Probiotics in Autism
16:06 – Nutrition Reviews Study on Mediterranean Diet
19:28 – Study on Gluten- and Casein- Free Diet
21:48 – Review on Ketogenic Diet
26:16 – Food, Nutrition, and Autism
27:57 – Systematic Review – Food as Medicine
34:40 – Clinical interpretation and application
40:30 – Micronutrients
44:10 – Q&A

Prospective Study on Amino Acid Patterns 

Dr. Barnhill outlines a 2025 study on amino acid patterns in over 1,200 children (2-8 years) with autism. Researchers found lower levels of glutamine in children with autism and significant differences in several amino acids across groups (2:00). Specifically, the study noted that those with neurological impairment were deficient in amino acids that presented with susceptibility to neurocytotoxicity and oxidative stress, while those with nutritional concerns presented with a different set of issues, pointing more toward metabolic concerns. Barnhill explains that these findings substantiate clinical observations and suggest that specific amino acid imbalances may be related to different manifestations of autism, supporting the use of nutritional therapeutic intervention to balance amino acid levels. The speaker emphasizes that this is the only amino acid study presented in a prospective way that has been published in a reputable journal in the past few years. 

Amino Acid Patterns in Children with Autistic Spectrum Disorder: A Preliminary Biochemical Evaluation (Ferraro et al., 2025)

Prospective Study on Probiotic Intervention 

The presenter outlines another recent study that speaks to the concerns of effects of probiotic support for children with autism, AD/HD, and children with both diagnoses (AuDHD) (5:50). Children were given a probiotic or a placebo for three months. Researchers saw a significant improvement in hyperactivity and impulsivity in both the autism and ADHD groups. Most notably, the “comfort score” on a quality-of-life instrument showed significant improvement for autistic children. Barnhill notes that, although this is a small study, its findings support clinical observations that probiotics can improve gastrointestinal symptoms and other related issues in children with autism, potentially impacting their quality of life.

Effect of Probiotics on the Symptomatology of Autism Spectrum Disorder and/or Attention Deficit/Hyperactivity Disorder in Children and Adolescents: Pilot Study (Rojo-Marticella et al., 2025)

Systematic Review of Dietary Intervention and Gut Health 

Barnhill examines a systematic narrative review of all articles published between 2000 and 2024 related to autism, dietary interventions, probiotics, and the microbiome. (25-year review) (7:40). The review validated that dietary intervention can improve GI symptoms and gut health for children with autism, which in turn improves their quality of life. Researchers also identified a cycle where sensory processing issues lead to food avoidance (ARFID), which decreases microbiome diversity and increases harmful microbial species, leading to a neuroinflammatory process that affects behavior (9:12). The speaker asserts that this review provides a strong rationale for addressing GI and microbiome concerns as part of a comprehensive care plan for individuals with autism.

Unraveling the Connections: Eating Issues, Microbiome, and Gastrointestinal Symptoms in Autism Spectrum Disorder (Tomaszek et al., 2025)

Bibliometric Analysis of Influential Articles 

The speaker highlights another 25-year study that reviewed all publications on microbiome treatment in autism since 2000 to identify the most impactful and cited articles (10:54). This is one of the first in a series of bibliometric analyses. The study identified two landmark publications: a 2013 mouse model study that established the link between the gut microbiome and ASD, and a very early, relatively small study from 25 years ago that showed improvements in both GI symptoms and behavior in a small group of autistic children treated with an oral antibiotic. These two studies, along with many more, laid the groundwork for the growing field of gut-brain research in autism and further validated the clinical utility of targeting gut health.

Influential articles in autism and gut microbiota: bibliometric profile and research trends (Ying et al., 2025)

Systematic Review of Probiotics in Autism 

Barnhill discusses a systematic review that analyzed 10 completed and published clinical studies, as well as 18 ongoing clinical trials, on the use of probiotics in autism. (13:47). Reviewers found that probiotics can improve social behaviors, drastically improve GI symptoms, and positively alter the gut microbiome when used appropriately. The presenter emphasizes this paper as a valuable and easily accessible resource for clinicians and parents, as it provides research backing for the use of probiotics in addressing a range of symptoms beyond just GI issues – essentially describing what we’ve learned and why it’s important.

Probiotics in autism spectrum disorders: a systematic review of clinical studies and future directions  (Barba-Vila et al., 2025)

Nutrition Reviews Study on Mediterranean Diet

Barnhill notes that we are seeing more and more solid research emerging about how dietary intervention benefits individuals across the board, highlighting that there is no one-size-fits-all approach for any of us and what that means for clinical applications. She outlines a 2025 evaluation of all studies on children (6-16 years) with autism and ADHD, examining responses to nutritional interventions (16:06). The paper concluded that 70% of individuals who followed a Mediterranean diet showed significant improvement in ADHD symptoms. It also noted significant improvements in depression (80%) and anxiety (50%). The speaker states that these results suggest that focusing on a whole, unprocessed Mediterranean-style diet can be a profound and effective intervention for improving neurological and mental health symptoms. 

Mediterranean Diet and Mental Health in Children and Adolescents: A Systematic Review (Camprodon-Boadas et al., 2025)

Study on Gluten- and Casein-Free Diet

The speaker outlines another 2025 study that evaluated a 12-week trial involving 80 children (4-10 years), using a strict, prescribed gluten- and casein-free diet in combination with and separate and distinct from a neurodevelopmental physical therapy program (19:28). Barnhill notes that families prepared meals on their own, meaning there was no technical control group. Researchers saw significant gains in gross motor skills and cognitive function only when the diet was combined with the therapy program. The dietary group alone showed no significant changes. This study suggests that a multidisciplinary, holistic approach is key, and that dietary interventions may be more effective when combined with other therapies.

Effect of Therapeutic Diet Along with Special Physiotherapy Program on Gross Motor Development and Cognitive Function in Autistic Children: A Randomized Controlled Trial (Alsayegh et al., 2025)

Review on Ketogenic Diet

A review of all published papers on the ketogenic diet for individuals with autism found that the diet is not appropriate for everyone due to the high heterogeneity of autism. However, Barnhill continues, it does hold great potential for some individuals by reducing bacterial dysbiosis, decreasing pro-inflammatory cytokines, enhancing gut health, and providing a neuroprotective effect via ketone bodies (21:48). Barnhill underscores that while the ketogenic diet can be effective for the right patient, it should only be implemented with professional guidance due to its complexity and potential dangers when applied inappropriately. More research is needed.

Exploring the potential of the ketogenic diet in autism spectrum disorder: metabolic, genetic, and therapeutic insights (Schrickel et al., 2025)

Food, Nutrition, and Autism

The presenter provides a summary article describing our current understanding of nutrition and autism from a societal and cultural perspective. The paper tangentially addresses all the issues that people in the US should be aware of and attuned to, including environmental and food exposures from prenatal to childhood. Barnhill asserts this study is foundational for building an appropriate dietary approach and understanding what barriers might exist (26:16). 

Food, nutrition, and autism: from soil to fork (Shepard et al., 2024) 

Systematic Review – Food as Medicine

The speaker notes a recent systematic review that addresses the use of dietary intervention and therapeutic nutritional support across various diagnoses (27:57). The authors highlight several publications that support the idea that food can be considered a form of medicine and is increasingly understood as a pharmaceutical component in health and medical diagnoses. Barnhill emphasizes the importance of not viewing food choices and dietary recommendations for autism as “other” to the general population’s nutritional understanding. Culturally, we continue to recognize that our diets are integral to health and need to be taken seriously. She states that “we need to hold autism research and interventions to the same standards.” This study ultimately resolidifies the interconnectedness of the gut and brain by highlighting the impact of microbiome health in the GI system on both the vagal nerve and cognition (31:00). 

Nutraceuticals in Psychiatric Disorders: A Systematic Review (Bozzatello et al., 2024)

Clinical interpretation and application

According to the presented information, Barnhill asserts that clinicians should assume that diet matters and that a nutritionist or dietary specialist should be included in care counseling and planning for children and adults with autism (34:40). She underscores the importance of avoiding packaged food products, ensuring fiber and water intake are sufficient, and addressing feeding concerns with care and compassion. She also suggests incorporating family and community into diet changes, meal preparation, and eating habits. The speaker also suggests working with a professional to outline any specialized diets (37:40). 

Micronutrients & Therapeutic Support

Barnhill lists common micronutrient deficiencies, including B vitamins, fat-soluble A and D, and Omega-3 fatty acids. She notes that addressing gaps with supplemental support is reasonable and appropriate to meet the minimal needs in the case that someone doesn’t have access to those nutrients via diet (40:30). She cautions viewers about the supplement market, noting that it is not regulated; and suggests consulting with someone well-versed in what’s needed and the efficacy of different brands before the Q&A (44:10). 

Contributors (listed in alphabetical order)

Vanessa H. Bal, Ph.D., Graduate School of Applied & Professional Psychology, Rutgers University; Margaret L. Bauman, M.D., Associate Professor of Anatomy and Laboratory Medicine, Boston University School of Medicine; Mary Doherty, M.D., Clinical Associate Professor, University College Dublin School of Medicine; Stephen M. Edelson, Ph.D., Autism Research Institute, San Diego, CA; Dena L. Gassner, Ph.D. (c), Senior Research Scientist, AJ Drexel Autism Institute: Drexel University; Robert L Hendren, DO, Professor of Psychiatry Emeritus, UCSF, Autism Research Institute; Wenn Lawson, Ph.D., A/Prof, Curtin University, Western Australia; David B. Nicholas, Ph.D., Faculty of Social Work, University of Calgary; Christopher Palmer, M.Sc., Commission for the Rights of Persons with Disability, Malta; Gaetano Alistair Savour, Ph.D., Chairperson, Autism Advisory Council, Ministry for Inclusion and the Voluntary Sector, Malta; Fakhri Shafai, Ph.D., AIDE Canada, Richmond, BC

For many years, the autism community focused nearly all of its attention on the needs of children and adolescents. As the prevalence of pediatric autism diagnoses has increased over the past three decades, researchers and service providers have broadened their focus to include the needs of individuals transitioning to adulthood and young adults. Today, there is increasing recognition of the importance of supporting autistic individuals throughout the entire lifespan, including old age.

In a 2017 report to Congress, the U.S. Department of Health and Human Services estimated that approximately 50,000 autistic youth are expected to transition into adulthood each year in the United States. Over the coming decades, a growing wave of these individuals will be entering later adulthood. Medicaid enrollment data has shown a steady increase in service use for this group.

The issue of aging in autism began to gain attention about a decade ago, and continues to grow in importance as rising numbers of autistic individuals age into their senior years. Prominent autistic individuals who are now over 60 years of age—including Temple Grandin, Stephen Shore, John Elder Robison, Wenn Lawson, Cos Michael, and Mark Rimland, the son of Dr. Bernard Rimland—highlight the relevance of this issue.

Some of the needs of autistic seniors, such as the requirement for appropriate living arrangements and good health care, appear straightforward. However, many less-obvious challenges are becoming clear as we are now hearing from autistic individuals approaching their senior years as well as from clinical and community researchers who are studying aging.

To explore these challenges, a dedicated group of autistic individuals and researchers has been meeting nearly monthly for approximately five years to discuss aging-related issues. This group has organized two major think tanks, resulting in published articles discussing their findings and conclusions (Edelson et al., 2023; Nicholas et al., 2025).

This group is currently planning a third think tank meeting at the United Nations, scheduled for next month (October 3, 2025). In preparation for this upcoming event, several additional autistic individuals have joined the planning committee to help determine important topics for discussion.

Recently, during one of their planning meetings, I was struck by the sheer number and complexity of senior-related issues identified by participants. To help prioritize these topics for the upcoming U.N. think tank, I asked the participants to rank these topics based on their perceived importance.

As the result of this ranking, the identified topics have been grouped under five key areas:

In the area of Physical and Mental Health in Aging, participants noted concerns related to dementia, Parkinson’s disease, extrapyramidal symptoms, and other age-related medical conditions (e.g., cancer, cardiac disease, stroke). They also stressed the importance of understanding the impact of medications on aging autistic individuals and exploring implications of hypermobility in older autistic adults (for example, those with Ehlers-Danlos syndrome). The broader spectrum of physical and mental health challenges associated with aging was recognized as posing concerns requiring urgent attention.

Regarding Healthcare Access, Navigation, and Delivery, participants highlighted menopause as an area in which there are significant unmet healthcare needs. They also emphasized the importance of making healthcare systems easier to navigate and reducing administrative burdens and bureaucratic barriers. Additionally, there was considerable concern about addressing the needs of autistic seniors requiring long-term care or acute medical treatment, including issues involving hospital admissions. Preparing autistic adults to communicate effectively with healthcare providers during medical visits was also identified as a critical area, along with addressing sensory sensitivities and nutritional needs in outpatient surgery units, long-term care facilities, and other healthcare environments. Participants noted that differences in sensory processing, communication, and stress response among autistic individuals may complicate the recognition and treatment of age-related health conditions, often leading to misdiagnosis or delayed care. They also stressed that autistic individuals should receive routine preventive care, including colonoscopies, prostate screening, and mammograms. Tailored clinical approaches that account for neurodivergent aging trajectories are urgently needed.

In the domain of Community, Autonomy, and Daily Life, the benefits of receiving a late autism diagnosis and self-recognition in older adults were highlighted. Community living options, regular health screenings, and protection from financial vulnerability were viewed as crucial for maintaining autonomy and quality of life. Participants noted the importance of supporting autistic individuals’ rights and legal capacity, while examining mechanisms such as guardianship and newer avenues such as supported decision-making and co-decision-making. Additionally, loneliness, social isolation, and parenting challenges faced by aging autistic adults—particularly those diagnosed later in life—were identified as vital areas of concern.

Social Determinants of Health and Discrimination also emerged as critical issues, with contributors expressing deep concern about ableism, ageism, housing insecurity, retirement, and forced retirement. Intersectionality, especially involving LGBTQIA+ and other multi-marginalized identities, was underscored as needing more focused attention. Participants also suggested learning from other sectors, such as the LGBTQIA+ community, in order to better address systemic issues.

Finally, End-of-Life and Palliative Care was recognized as an essential area needing more comprehensive planning and support. Participants emphasized the importance of respectful and informed end-of-life decision-making and palliative care tailored specifically for autistic individuals, including making clear and accessible communication readily available.

The richness and complexity of the issues discussed illuminate an undeniable reality: Proactive engagement and systemic preparation are vital. Addressing these topics not only will aid autistic adults in navigating their later years but also will help to build an essential framework for policymakers, caregivers, support persons, healthcare providers, and society at large. Enhanced research, informed policy development, and dedicated resources will ensure that autistic seniors can live with dignity, autonomy, and comprehensive support. Critical to this aim is the key role and contribution of autistic people themselves in determining their priorities and what is needed in their middle and later years.

It is crucial that ongoing dialogues and forthcoming initiatives foster increased awareness among autistic individuals, families, support networks, healthcare practitioners, and policymakers. Collectively, these collaborative efforts can drive meaningful changes in both practice and policy, ultimately creating a world where autistic seniors can thrive throughout their aging process.

Although awareness of the needs of the aging autistic community is increasing, the time for action is now. We must seize this momentum to ensure that autistic seniors experience the highest possible quality of life, made possible by informed, compassionate care, oversight, and support and a well-designed infrastructure capable of meeting their evolving needs.

References available at www.ARRIReferences.org.

This editorial originally appeared in Autism Research Review International, Vol. 39, No. 3, 2025

Blythe A. Corbett, Ph.D., discusses her lab’s research on puberty, adolescence, and mental health in autistic individuals. She emphasizes puberty as a period of significant biological maturation involving several physical, biological, hormonal, and social factors. The speaker details her lab’s latest research on pubertal onset, mental health, hormonal changes, and gender identity in autistic young people compared to allistic (non-autistic) groups. Corbett repeatedly emphasizes how puberty can be particularly complex for autistic youth (especially those assigned female at birth), who are already vulnerable to change and stress. She summarizes the presentation and underscores the importance of exploring how puberty’s hormonal, psychological, and social changes interact with the autism phenotype before the Q&A.

Handouts are online HERE

In this webinar:

1:15 – Outline
5:10 – Adolescence, puberty & associated risks
9:25 – Measuring puberty
13:15 – Autistic vs. allistic pubertal onset
19:00 – Cortisol levels in autistic young people
25:25 – Depression in young people with autism
32:15 – Testosterone and development
37:00 – Gender identity
43:00 – Conclusions & future research
47:30 – Q&A

Adolescence & puberty in autism

Corbett describes autism as a neurodevelopmental condition characterized by differences in social communication (e.g., social-emotional reciprocity, non-verbal communication) and restricted, repetitive patterns of behavior, interests, or activities (e.g., insistence on sameness, sensory sensitivities) (01:35). Adolescence, she explains, is a transformative stage characterized by significant psychological, social, emotional, and hormonal shifts, typically spanning ages 10 to 24. Within this broader period of adolescence, puberty specifically marks the biological maturation that leads to reproductive capacity and further psychosocial development (5:10). For autistic individuals, who often experience challenges with social communication, adaptability to change, and sensory sensitivities, navigating these developmental milestones can be particularly complex.

The presenter explains that early onset puberty can increase the risk for mental health problems, such as anxiety, depression, and suicidality, which are already more prevalent in adolescents with autism (05:58). Until recently, research on puberty and autism has been limited. Some recent studies suggest that while social cognition might improve during puberty, social withdrawal can intensify, and about a third of youth experience significant psychosocial problems. Further, female-presenting autistic people have reported challenges with emotion regulation and heightened sensory experiences during menstruation (08:06).

• A Two-Hit Model of Autism: Adolescence as the Second Hit (Picci & Scherf, 2015)
• Changes in Maladaptive Behaviors From Midchildhood to Young Adulthood in Autism Spectrum Disorder (Anderson et al., 2011)
• Autism after Adolescence: Population-based 13- to 22-year Follow-up Study of 120 Individuals with Autism Diagnosed in Childhood (Billstedt et al., 2005)
• Autism spectrum disorders and menstruation (Hamilton et al., 2011)
• In Search of Explanations for Early Pubertal Timing Effects on Developmental Psychopathology (Ge & Natsuaki, 2009)
• Pubertal Timing, Depression, and Externalizing Problems: A Framework, Review, and Examination of Gender Differences (Negriff & Susman, 2011)
• Other-Sex Relationship Stress and Sex Differences in the Contribution of Puberty to Depression (Llewellyn et al., 2012)
• Depressive and Anxiety Symptom Trajectories From School Age Through Young Adulthood in Samples With Autism Spectrum Disorder and Developmental Delay (Gotham et al., 2015)

Puberty onset and measurements

Corbett briefly describes methods for measuring puberty, including Tanner staging (physical exam), parent report (e.g., Pubertal Development Scale), and self-report (e.g., gender-specific self-assessment questionnaire) (09:27). She outlines a recent publication by her team which found that pubertal assessments by parent or child are not reliable indices of precise pubertal staging, compared to physical exams (11:05). Corbett and her team use all three methods of measurement in their studies to compare perceived development with physical indices. The speaker touches on models and frameworks used to help understand the links between mental health, puberty, and autism.

A study published by Corbett and colleagues in 2020 shows that autistic females experience significantly earlier breast development and onset of menses compared to typically developing females, while pubertal onset for autistic males is similar to neurotypical males (13:15). A longitudinal study assessing the progression of puberty in the same participants between 10 and 15 years of age verified these findings. Corbett reiterates that pubertal onset “sets into motion a cascade of events which may magnify and further complicate an already vulnerable trajectory, especially in females (17:00).” 

• Pubertal Development Measurement in Children With and Without Autism Spectrum Disorder: A Comparison Between Physical Exam, Parent- and Self-Report (Corbett et al., 2019)
• Pubertal Timing During Early Adolescence: Advanced Pubertal Onset in Females with Autism Spectrum Disorder (Corbett et al., 2020)
• Examination of pubertal timing and tempo in females and males with autism spectrum disorder compared to typically developing youth (Corbett et al., 2022)

Altered cortisol levels in autism

The speaker describes the Hypothalamic-Pituitary-Adrenal (HPA) axis, which plays a vital role in our stress response by triggering a neuroendocrine cascade to produce cortisol. Cortisol, she continues, is a widely used biological marker found in blood and saliva (19:00). Normally, cortisol levels peak in the morning and decline throughout the day. However, Corbett’s research consistently shows that autistic children exhibit significant variability in cortisol levels, with persistently elevated evening cortisol and a “blunted slope” compared to their allistic peers. This means their cortisol doesn’t rise or drop to the same level, impacting their ability to feel energized during the day and rest well during the night (20:30). Another longitudinal study on cortisol trajectory further revealed that HPA axis maturation is impacted by age, puberty, sex, and an autism diagnosis, where females had higher overall cortisol and higher evening cortisol than the males in both groups (22:00). 

• The developmental trajectory of diurnal cortisol in autistic and neurotypical youth (Corbett et al., 2023)

Psychological well-being: depression in autistic adolescence

The presenter notes that half of all people who will suffer from mental illnesses have their onset by age 14, making adolescence a critical period for mental health, especially for autistic youth. A study conducted by Corbett and Dr. Jessica Schwarzman found that depressive symptoms are significantly higher in both autistic males and females as early as 10-13 years of age. Parents corroborated these findings, reporting higher depressive symptoms in their autistic children, especially in females (25:25). The presenter therefore asserts that screening and intervention for depressive symptoms for autistic individuals should begin very early in adolescence. She notes that symptoms were often related to interpersonal problems and feelings of worthlessness, which are crucial intervention targets (28:00).

Corbett outlines a recent longitudinal study on the trajectory of depressive symptoms which revealed that while autistic individuals reported significantly higher depression symptoms at age 10, their symptoms actually decrease through adolescence, contrasting with an increase seen in allistic youth around ages 14-15 (30:00). The speaker notes that if replicated, this data warrants significant attention, potentially pointing to earlier identification and treatment for autistic youth.

• Higher depressive symptoms in early adolescents with Autism Spectrum Disorder by self- and parent-report compared to typically-developing peers (Schwartzman & Corbett, 2020)
• Diagnostic- and sex-based differences in depression symptoms in autistic and neurotypical early adolescents (Schwartzman et al., 2022)
• Trajectory of depressive symptoms over adolescence in autistic and neurotypical youth (Corbett et al., 2024)

Hormonal differences

Corbett explains that imbalances in hormones such as testosterone may modulate autism phenotypes. However, there is limited research regarding variations in testosterone during adolescence in autism (34:15). She details a recent study comparing salivary testosterone between autistic and allistic groups and male vs. female participants, with considerations of developmental stage. Data show that in autistic youth, both males and females exhibited significantly elevated testosterone compared to allistic youth. While male testosterone levels rapidly increased as expected during adolescence, females initially had higher testosterone until around 11.5 years of age before plateauing. Corbett states that these findings may suggest testosterone does play a role in autism, especially during periods of hormonal change (36:00). 

• Salivary testosterone in male and female youth with and without autism spectrum disorder: considerations of development, sex, and diagnosis (Muscatello et al., 2022)

Gender diversity in autistic young people

Adolescence is a time of profound self-exploration, including gender identity, or a person’s innate sense of gender. The speaker highlights recent research suggesting a higher prevalence of gender diversity in individuals diagnosed with autism or having autistic traits compared to their allistic peers. Corbett’s team used both self-report and parent report questionnaires to confirm this finding in autistic children (37:00). Parents of autistic children reported significantly greater “gender body incongruence” in their children compared to parents of allistic children. Furthermore, within the autistic group, those assigned female at birth reported significantly more experiences of gender body incongruence than those assigned male. Self-reports from autistic youth also indicated significantly more reports of both “gender diversity” and “non-binary diversity” (40:00).

A follow-up study assessing gender diversity throughout adolescence found that gender incongruence was relatively stable across puberty in males (autistic and allistic). In contrast, autistic females endorsed greater incongruence around age 10, followed by a short plateau and then another increase. Allistic females reported the opposite pattern. Corbett summarizes these findings, highlighting the sex-based differences that indicate greater gender diversity in autistic females assigned at birth (AFAB). She also reiterates that gender identity formation is nuanced and likely influenced by pubertal progression, hormone patterns, and psychosocial factors (42:00). 

• Greater Gender Diversity among Autistic Children by Self Report and Parent Report (Corbett et al., 2023)
• Gender diversity in autistic and neurotypical youth over adolescence and puberty: A longitudinal study (Corbett et al., 2024)

Conclusions & future research

Corbett summarizes the presentation, highlighting that autistic females enter puberty earlier than autistic males and allistic groups. Autistic young people also have a higher rate and earlier onset of depression and a greater prevalence of gender diversity, especially in females. The speaker underscores the need for comprehensive measurements of psychological variables based on self-report, parent-report, and clinical-report. She emphasizes the need to identify risks and opportunities for resilience to elucidate and support the dynamic transition of puberty (43:00). 

Corbett and her team recently received funding to renew their longitudinal study of pubertal development. The renewed study aims to examine pubertal development through age 17 by observing physical development, hormones, menstruation, social communication, and internalizing symptoms. It also aims to observe the nervous system during these periods in a group of more than 300 participants (45:00). She notes an ongoing female development study before the Q&A (47:30). 

Originally published January 29th, 2025

Mojdeh Mostafavi, MD, shares her deeply personal journey as a sibling supporting a loved one with profound autism. She describes her experiences from early childhood through adulthood, highlighting the challenges and triumphs that her family and care team have experienced. The speaker shares ten meaningful insights about her family’s journey, highlighting the importance of communication and advocacy from a very young age. Mostafavi emphasizes the complexities of ever-evolving sibling relationships before the Q&A. 

In this webinar

2:00 – Introduction
4:30 – Early life, diagnosis, and family response
9:00 – The role of siblings and at home care
14:05 – Behavioral challenges during adolescence
17:00 – Adulthood milestones and medical crises
21:30 – Ongoing care and the unknown future
23:00 – Welcome to Holland – a sibling’s perspective
27:00 – Ten reflections from an adult sibling of someone with profound autism
34:00 – Communication challenges and triumphs
43:00 – Family, community, care teams — the importance of support
47:40 – Q&A

Early Life, Diagnosis, and Family Response

Mostafavi’s brother was born in 1995, when she was just two years old. During pregnancy and early infancy, his development seemed uncomplicated. However, at around 18 months, their parents, both medical professionals, noticed a profound developmental regression. He began losing words as he learned new ones, stopped responding to his name, started to avoid eye contact, and exhibited classic stimming behaviors like lining up toys, hand flapping, and finger twisting. The speaker explains that this regression occurred within a five-or six-week period, during which his preschool teacher suggested they get an autism assessment (4:30).  

In 1996, her brother was diagnosed with autism; this was a traumatic experience for her parents, who received a largely negative prognosis. Her parents recall being told that he would likely never speak or live independently and that many strongly suggested institutionalization. Mostafavi reminds viewers that during the mid-1990s, autism prevalence was reported as 1 in 10,000, so there was very little understanding or resources available (7:00). Undeterred, her parents embarked on a journey of self-education, extensively researching interventions and support strategies. They successfully pioneered a home-based program to address their son’s profound needs in an area with few specialized services.

The Sibling’s Role: Integration and Transformation

Growing up, Mostafavi’s life was intrinsically linked to her brother’s care. Their home was a hub for various therapies, including occupational therapy (OT), speech-language pathology (SLP), and ABA. From a young age, she was actively involved in these sessions, often tasked with modeling behaviors or assisting therapists. The speaker emphasizes how this deep involvement made her feel valued and important, which mitigated feelings of being a “glass child” and fostered an understanding and supportive sibling relationship (9:00). It was in her elementary years, around ages six to eight, that she first recognized the unique differences in her family life compared to her peers (12:00). 

Adolescence and Behavioral Challenges

Adolescence proved to be an exceptionally challenging period for her brother, particularly due to his limited verbal communication skills and subsequent difficulty expressing his needs and emotions. These challenges often led to intense behavioral outbursts, primarily aggression, including hair pulling, scratching, and biting, usually received by herself or her mother (14:05). Mostafavi underscores that her brother showed remorse after such outbursts, highlighting not only their close bond, but also the lasting distress externalized behaviors can have on everyone involved. The hormonal shifts of puberty further complicated her brother’s ability to self-regulate. The presenter recalls the incredible support they received from her brother’s care team and how they assisted in navigating this challenging moment for their family (15:00). Mostafavi notes her brother’s naturally loving disposition, stating that, even in these hard moments, 95% of the time, it was just awesome. It was that 5% where he struggled with communication that would result in aggressive behaviors.

Adulthood and medical crises

Mostafavi highlights that her experience differs from many because all the support systems they had took place in their home. During early adulthood, her brother reached many key milestones, like going to the movie theater, getting his first hair cut at the barber, and getting his wisdom teeth removed (17:00). The speaker briefly describes the first severe medical crisis her brother had when he was 27, which led to hospitalization and an induced coma. The cause was eventually traced to severe, unexpressed pain, leading to extensive medical evaluation and ultimately a diagnosis and intervention. The presenter comments on how disruptive it was to the entire family to be unable to manage and care for her brother at home. This process forced the family to reassess their resources, their son’s evolving needs, and the family’s well-being. It was a transformative period that instilled a deeper sense of awareness and appreciation for the ongoing challenges of supporting a loved one with profound autism (20:00).

Her brother remains at home with their parents, benefiting from a consistent care team, some of whom have been involved for over a decade. While aggression has subsided, he still experiences self-injurious behaviors, mainly head-hitting, often linked to unexpressed pain. The family is actively working with his medical team to mitigate these symptoms and behaviors. Despite these ongoing challenges, a home-based program with his long-standing care team remains the most effective option for his needs (21:30).

Reflections on the complexities of being a sibling

To articulate the sibling experience, the speaker references Emily Pearl Kingsley’s poem, Welcome to Holland, originally about the parental journey of having a child with special needs. Mostafavi adapts this analogy to the sibling perspective, explaining that a child growing up in “Holland” (a life with a sibling with autism) doesn’t initially understand the concept of “Italy” (a typical life). As they grow, they begin to recognize differences and form their understanding of the world, realizing that “Holland” is the only life they’ve ever known. This perspective highlights that the complexity and evolution of their unique life journey only become fully appreciated in adulthood (23:00). 

The speaker provides ten insights/reflections on her experiences as a sibling of someone with profound autism. She emphasizes the multifaceted and ever-evolving nature of the sibling relationship, explaining that their dynamic constantly shifts as both individuals navigate life stages—childhood, adolescence, and adulthood. For Mostafavi, this role often includes aspects of caregiving and, in the future, the role of guardian (27:00). She clarifies that her experience doesn’t align with the “glass child” concept because of her deep integration into her brother’s care, which made her feel valued. However, she acknowledges the profound and complex emotional and psychological impact, including feelings such as hurt, anger, guilt, frustration, love, sadness, and grief. All of these require continuous coping strategies even today (30:00). 

A significant aspect of the speaker’s experience is the unique “language” or means of communication she shares with her brother and sister. Living with someone with substantial verbal communication challenges has honed her ability to understand and interpret non-verbal cues (34:00). She touches on the importance of advocacy and empowerment from a young age and the complexities of planning for the future (40:00). Mostafavi asserts the importance of finding “your people” and navigating social life and relationships. The power found in people who support, nourish, and understand the nuances of your life cannot be understated (43:00). The speaker ends by reminding viewers that these are her experiences and that this may look different for everyone. During the Q&A, she discusses therapy for siblings and much more (47:40). 

Originally published on January 6th, 2025