Autism Linked to Higher Risk of Parkinson's-Related Disorders in Older Adults, Study Finds

Older adults diagnosed with autism face a substantially higher risk of developing Parkinson’s disease-related movement disorders compared to the general population, according to a large study published in the journal Autism. Researchers analyzed Medicare and Medicaid claims data for nearly 57 million Americans aged 45 and older between 2017 and 2019.

The findings indicate that individuals on the autism spectrum, as well as those with intellectual disabilities, were diagnosed with parkinsonism at much higher rates than those without these conditions. Parkinsonism refers to a group of neurological conditions characterized by symptoms such as tremors, muscle rigidity, balance difficulties, and slowed voluntary movement.

Previous research had suggested a connection between autism and motor decline later in life, but it was unclear whether these issues stemmed from the condition itself or from antipsychotic medications, which are known to cause Parkinson's-like symptoms. To address this, the researchers excluded individuals taking antipsychotics from their analysis and still observed higher rates of Parkinson’s-related diagnoses in neurodivergent populations.

In the general population control group, the prevalence of parkinsonism was approximately 1.57%. This rate increased to 3.83% among adults with autism alone, 4.32% for those with an intellectual disability alone, and 4.86% among individuals diagnosed with both autism and an intellectual disability.

"A critically important new contribution of this study is increased incidence rates of parkinsonism for autistic people in middle and older adulthood, which suggests that these cases aren’t simply a byproduct of lifelong motor challenges," said Greg Wallace, lead author and a professor at The George Washington University. The study is noted as the first to track the incidence rate of newly emerging cases over time among older autistic individuals.

Dr. Lee Murray, a neurologist not involved in the study, commented that this research clarifies previous findings by accounting for antipsychotic medications, which can mimic Parkinson's symptoms. He emphasized that the study shows the greatest association with concomitant Parkinson's among patients with autism coupled with an intellectual disability.

Murray cautioned that autism is a broad spectrum, and the findings do not imply that all individuals with autism face a significantly higher risk. He added that it is clinically helpful for physicians to review medications with autistic patients and consider avoiding those that might induce Parkinson's-like symptoms. He also noted that atypical movements in autistic individuals could be misdiagnosed as Parkinson's by less experienced clinicians.

The study's authors acknowledged limitations, including the reliance on Medicare and Medicaid billing records, which may contain diagnostic coding errors. The data also did not allow for assessment of symptom severity, lifestyle factors, genetics, or family history. Furthermore, the analysis was limited to individuals with public insurance, potentially excluding those solely relying on private health insurance.

Despite these limitations, the researchers stressed the importance of close monitoring of older autistic patients for motor decline by physicians, care facilities, and caregivers to enable early intervention.