Study Links Autism and Intellectual Disability to Higher Parkinsonism Rates

Older Americans with autism, intellectual disability or both were diagnosed with Parkinson’s disease or related movement disorders at about two to three times the rate of other adults, according to a peer-reviewed analysis of Medicare and Medicaid claims. The researchers and an outside neurologist caution that the findings show a link, not a cause.

The study appeared in the journal Autism on Oct. 24, 2026, and was summarized by HealthDay News on Oct. 28 and Fox News on Oct. 30. Greg Wallace of George Washington University’s Department of Speech, Language and Hearing Sciences is the lead author. The analysis covered nearly 57 million Americans aged 45 and older whose records spanned 2017 to 2019. It is observational: it counts diagnoses in insurance claims and does not examine patients. Neither news report names a funder, and the paper’s funding disclosure was not reviewed for this article.

The share of people with a parkinsonism diagnosis was about 1.57% among adults with neither condition, 3.83% among those with autism alone, 4.32% among those with intellectual disability alone, and 4.86% among those with both, as Fox News reported the figures. In absolute terms, that is a gap of roughly 2.3, 2.8 and 3.3 percentage points. In relative terms, by this paper’s arithmetic on those numbers, the rates are about 2.4, 2.8 and 3.1 times the comparison group’s.

HealthDay reported age-standardized rates per 100,000 person-years of 1,341 for people with both autism and intellectual disability, 1,017 for intellectual disability alone, 977 for autism alone and 234 for the comparison group. The elevated risk persisted after the authors adjusted for prescribed medications, HealthDay reported, though the researchers noted that antipsychotic drugs, which are used more often in these groups, can themselves cause parkinsonism-like symptoms.

Wallace said the cases “aren’t simply a byproduct of lifelong motor challenges,” and that clinicians should “establish clear baselines of motor skills and challenges during adulthood,” according to HealthDay. Dr. Lee Murray, a neurologist who was not involved in the study, told Fox News, “It certainly is an interesting correlation, although it does not imply that someone with autism is certain to develop Parkinson’s.” He added that atypical movements common in autism can be misread as Parkinson’s, which could inflate the counts.

That last point is the study’s main limit. Claims data record what doctors billed, not necessarily what patients have, and the people studied are those enrolled in Medicare or Medicaid, which may not represent all older adults. Even so, the authors’ practical suggestion is modest: for adults with these conditions, a documented baseline of movement would help doctors tell lifelong differences from new symptoms.

Most older adults with autism or intellectual disability, even on the study’s highest figure, did not have a parkinsonism diagnosis. About 95 in 100 people in the highest group had none.