People with autism are at a much higher risk of developing dementia, according to a major new study.
Researchers from Drexel University in Philadelphia, Pennsylvania, linked the rapidly growing condition to a four- to-eight-time higher risk of the memory-robbing disorder compared to the general population.
The authors reviewed two studies: A 2019 study on ASD and dementia among autistic adults enrolled in Medicare and a 2021 study on the incidence of early-onset dementia among adults with ASD enrolled in Medicaid.
They analyzed the data of 114,600 people 30 or older from 2008 to 2017 who had a diagnosis of ASD and ASD plus another intellectual disability (ID).
About one in 36 US children and one in 45 adults have autism, according to the CDC – though that number is rapidly growing – and previous research has revealed a ‘known association between intellectual disabilities (IDs) and dementia.’
Overall, the review found dementia diagnoses were present in eight percent of people who had previously been diagnosed with ASD and in nearly nine percent of people who had ASD plus another ID.
In 2022, four percent of all adults 65 and older had ever received a dementia diagnosis – with Alzheimer’s disease the most common form of dementia, diagnosed in nearly 7million Americans.
The 2025 review also found the odds of a dementia diagnosis increased with age.
Among people 65 and older, 35 percent of people in the ASD-only group and 31 percent of people in the ASD plus another ID group had dementia.
The researchers acknowledged a limitation of their study was the data spanned a wide timeframe and they said there was a need for more research.
Additionally, they wrote: ‘Our data highlight the importance of health policy efforts for the growing ASD population at risk for or affected by dementia.
‘Future research should address factors that might contribute to the cooccurrence of neurodevelopmental and neurodegenerative conditions, including barriers to accessing educational and social opportunities, as well as biological mechanisms of shared pathophysiology.’
Independently, the 2019 study found women with autism were 8.5 times more likely to have any sort of cognitive condition, which included dementia, compared to women without ASD.
Men with the condition were similarly 8.2 percent more likely to have a cognitive disorder, which also included delirium, amnesia and ‘other’ cognitive conditions.
However, those researchers acknowledged other studies have found older autistic adults are equally as likely or less likely to experience age-related cognitive changes, saying discrepancies exist because of the methodology used and the group of people studied, which range in age, a major contributor to cognitive disorders.
In the 2021 study, researchers found the prevalence of dementia among adults with ASD only was four percent and five percent among people with both ASD and another ID, compared to one percent of people without ASD or ID.
Researchers aren’t sure why there is a link between the two conditions, but the 2021 study said there may be a ‘potential overlap’ in the factors that cause both dementia and ASD, including shared genetic mutations.
And, dementia medications have been observed to work in reducing cognitive and communicative functioning in adults with ASD, which could point to a shared cause.
Additionally, a separate 2021 study found a number of genes and proteins have been linked to both ASD and Alzheimer’s disease, and the two conditions share multiple symptoms, including insomnia, weak neuromuscular function and dementia.
Autism diagnoses in America have surged in the last decade, data shows, and dementia diagnoses are expected to as well. While 7million Americans currently have Alzheimer’s disease, that number is expected to double by 2030.
Generally, most people with ASD are diagnosed by age five, though some can be tested as young as age two and dementia most commonly occurs in seniors.
A recent analysis of millions of health records found among all age groups, autism diagnoses rose 175 percent between 2011 and 2022, from a rate of 2.3 to 6.3 per 1,000 people.
The biggest increase was among young adults ages 26 to 34, with a 450 percent jump, though children ages five to eight are still the most likely group to be diagnosed – at a rate of 30 per 1,000.
While experts don’t know what causes the condition, recent research suggests environmental factors like pollution, illnesses during pregnancy, and older parental age could be to blame.
Better screening, raised awareness and a broader diagnostic criteria could also be driving the Autism surge.
Neither condition has a cure but medications, procedures and therapies are available to manage symptoms.