Editorial: Autism and Dementia and Alzheimer’s Disease

Aging introduces numerous challenges for autistic individuals, and one issue of concern—as it is for the general population—is the potential for rapid cognitive decline. This decline, commonly associated with dementia or Alzheimer’s disease, may pose unique difficulties for autistic individuals, who often contend with additional challenges such as anxiety, depression, gastrointestinal issues, insistence on sameness, memory impairments, sensory sensitivities, limited ability to communicate, and sleep disturbances.

It is important to note that dementia is a general term for cognitive impairments affecting memory, reasoning, and daily life. It can be caused by a variety of conditions, such as Alzheimer’s, vascular dementia, or Lewy body dementia. Alzheimer’s, the leading cause of dementia, accounts for 60-80% of cases. Understanding the distinction between dementia as a set of clinical symptoms and signs and Alzheimer’s as a specific disorder is essential for accurate diagnosis and treatment.

While research on the topic of dementia or Alzheimer’s disease in autistic individuals remains limited, emerging evidence presents a complicated picture. Some studies point to the possibility of a biological protective factor, noting a rarity of dementia or Alzheimer’s disease in the autism population. In contrast, other studies suggest a relatively higher prevalence rate than in the general population. This discussion will briefly summarize these findings and explore their potential implications.

Finding 1: Some data suggest that autistic individuals may be less susceptible to dementia

For some time, there has been speculation that autistic individuals might not experience dementia or Alzheimer’s, based on a lack of cases identified by experienced clinicians (Margaret Bauman, personal communication, December 2024). Over the past decade, several studies have supported this view.

Barnard-Brak et al. (2019) analyzed records of 1,754 autistic individuals from the National Vital Statistics System, spanning the years from 1999 to 2015. Their research focused on age at death and the prevalence of dementia-related disorders. The findings revealed that autistic individuals were less likely than the general population to develop dementia or Alzheimer’s disease.

In both longitudinal and cross-sectional studies, Torenvliet and colleagues administered a range of cognitive assessments, including assessments of memory, verbal fluency, processing speed, and self-reported cognitive issues, among others. Their findings revealed no significant evidence of sudden cognitive decline (Torenvliet et al.,2022, 2023).

Finding 2: Some data suggest that autistic individuals may be more susceptible to dementia

In a sample of 210 middle-aged and older autistic adults, participants completed a self-rated dementia questionnaire to assess cognitive decline. In contrast to the research cited above, the findings revealed that 30% reported experiencing cognitive decline (Klein et al., 2023). The most commonly reported symptoms included a reduced interest in leisure-type activities and increased difficulties with judgment in daily life, memory, and thinking.

Giacomo Vivanti and colleagues at A.J. Drexel Autism Institute published two large-scale studies involving insurance claims. In one study, they analyzed U.S. Medicaid claims data for both autism spectrum disorder (ASD) and Alzheimer’s disease and found that autistic individuals were approximately 2.6 times more likely to be diagnosed with early-onset Alzheimer’s disease and related dementias compared to the general population (Vivanti et al., 2021).

In a more recent study, Vivanti et al. (2025) analyzed both Medicare and Medicaid data from 2014 to 2016, involving 114,582 autistic individuals aged 30 years
and older, and reported that 8% of autistic individuals and nearly 9% of those with both autism and intellectual disabilities received dementia diagnoses. In addition, the prevalence of dementia increased sharply among those over 64 years of age, with 35% of individuals with ASD alone and 31% of those with both ASD and intellectual disabilities showing signs of dementia.

While Vivanti et al.’s studies were based on insurance claims data without clinical assessments, previous research indicates a high correspondence between claims-based and clinical diagnoses for autism (Burke et al., 2014) and for Alzheimer’s disease (McCarthy et al., 2022).

Interestingly, Rhodus et al. (2022) evaluated 56 individuals with mild cognitive impairment or dementia near the end of life using the Gilliam Autism Rating Scale, 2nd Edition, followed by postmortem neuropathologic assessments. Individuals categorized as “Autism Possible/Very Likely” exhibited higher neurofibrillary tangle density, increased tau burden in the frontal and temporal lobes, and a more significant neuritic plaque burden compared to those in the “Autism Unlikely” group. These findings may suggest a potential association between autism and increased tau pathology, a common characteristic linked to late-life dementia. However, the researchers did not report evidence of amyloid-containing plaques, which are considered a common marker of Alzheimer’s disease.

There is also indirect evidence suggesting that autistic individuals may have a predisposition to Alzheimer’s disease. Research from the general population shows that visual memory deficits can predict Alzheimer’s disease up to a decade before diagnosis (Kawas et al., 2003). Additionally, studies have documented significant visual memory impairments in autistic individuals. For example, Geurts and Vissers (2012) identified pronounced visual memory deficits in a group of 23 autistic seniors aged 51 to 83 years compared to a control group.

Making sense of this supposed discrepancy

Defining study populations and ensuring accurate diagnosis. To draw meaningful statistical inferences, it is important to clearly define the study population, whether it consists of a single group or multiple groups, such as controls and treatment groups. However, the cited studies demonstrate inconsistency in population definitions, ranging from Medicare/Medicaid recipients to high-functioning individuals with autism and, in some cases, broadly encompassing “all” individuals with autism.

In addition, there are issues regarding the accuracy of dual diagnoses in insurance claims. Autism and Alzheimer’s disease share substantial symptom overlap (Khan et al., 2016; Rhodus et al., 2020a, 2020b), which may lead to diagnostic misclassification. Additionally, valid statistical methods or results comparing dementia/Alzheimer’s prevalence between the autistic population under study and the general population are often lacking. Proper data analysis requires that measurements be well-defined, consistently applied, and representative of a random sample—criteria that are not always met in the current literature.

Recognizing the role of autism’s heterogeneity. When evaluating discrepancies in research findings, it is important to recognize the broad spectrum of autism presentations. While individuals formally diagnosed with autism share core symptoms, they vary significantly in the severity of their symptoms, their level of independence, and other factors. This heterogeneity may contribute to differences in dementia risk. Some autistic individuals may experience a sudden cognitive decline resembling dementia or Alzheimer’s disease, while others may not—mirroring the variability observed in the general population.

Moreover, the ability to diagnose dementia or Alzheimer’s in autistic individuals may depend on their baseline challenges. Those with fewer difficulties in social communication may exhibit more recognizable declines in orientation, memory, planning, problem solving, and personality. In contrast, for those with more pronounced lifelong challenges, these declines may be harder to detect, as they overlap with preexisting difficulties.

Moving toward more accurate diagnosis. To better understand the potential connection between autism and Alzheimer’s, research should prioritize examining specific brain regions associated with Alzheimer’s pathology. The study by Rhodus et al. (2022) highlights how neuroimaging may help identify impairments characteristic of Alzheimer’s disease. However, postmortem brain studies remain essential for confirming the presence of actual cases of dementia or Alzheimer’s disease. For further discussion on the importance of postmortem brain tissue research, see Natowicz et al. (2024).

Finally, given the limitations of research relying on insurance claims, a more refined approach to diagnosis is needed. Autism and dementia, including Alzheimer’s disease, share overlapping characteristics, which complicates classification. Developing a specialized behavioral checklist to document past and current behaviors may enhance the accuracy of identifying individuals with co-occurring autism and dementia or Alzheimer’s.

Final thoughts

Individuals with autism and dementia or Alzheimer’s disease will likely require considerable guidance and support, potentially exceeding the needs of those with only one condition or the other. Moreover, given the rapid decline typically associated with dementia and Alzheimer’s, it would be wise to implement appropriate procedures promptly. To adequately address this issue, healthcare providers will need specialized training to recognize dementia in individuals with autism, as well as to understand the potential for overlapping or masking of signs. It will be crucial to develop communication strategies that accommodate the individual’s sensory challenges and cognitive capabilities and to create environments that minimize stress and overstimulation.

Furthermore, caregivers and families of autistic individuals must be supported with resources and education tailored to this dual diagnosis. This includes guidance on managing behavioral changes, providing consistent routines, and accessing appropriate medical and therapeutic services.

Even if individuals with autism do not have an elevated risk for dementia—an issue still to be better understood—the high population prevalence of autism necessitates that specialists in autism, dementia, and Alzheimer’s work together to design interventions that address the unique needs of this population while promoting the best possible quality of life.

References available at www.ARRIReferences.org.

Stephen M. Edelson, Ph.D.
Chief Science Officer, Autism Research Institute

This editorial originally appeared in Autism Research Review International, Vol. 39, No. 1, 2025