Autistic adults over 45 are diagnosed with parkinsonism at nearly triple the rate of their peers, according to a new analysis of Medicare and Medicaid claims covering nearly 57 million Americans. The study, published this month, found a prevalence of 3.83 percent among autistic adults compared with 1.57 percent in the general population control group.
Higher Parkinsonism Prevalence in Autistic Adults
The gap widens when intellectual disability is part of the picture. Adults with an intellectual disability alone showed a parkinsonism prevalence of 4.32 percent. For those with both autism and an intellectual disability, the rate reached 4.86 percent. These figures represent recorded diagnoses in billing records, not just symptom reports, and they held steady even after researchers excluded anyone taking antipsychotic medications, which are known to cause Parkinson’s-like side effects.
Greg Wallace, the lead author and a professor in the Department of Speech, Language and Hearing Sciences at The George Washington University, said the incidence data, tracking new diagnoses over time, tells a critical story. “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,” Wallace said. This is the first study to track incidence rates of parkinsonism in this population.
How the Medicare-Medicaid Study Was Conducted
Researchers analyzed claims data for Americans aged 45 and older enrolled in Medicare or Medicaid between 2017 and 2019. The massive sample size, nearly 57 million people, allowed for comparisons between the general population and adults with autism, intellectual disability, or both conditions. The study relied on diagnostic codes recorded for billing purposes, which the authors acknowledge can contain errors or reflect differences in how providers identify conditions.
Because the data came from public insurance programs, the findings may not fully represent autistic adults who rely exclusively on private health insurance. The records also did not include information on the severity of movement symptoms, lifestyle factors, genetics, or family history.
Possible Mechanisms Beyond Medication Effects
The persistence of higher rates after stripping out antipsychotic users points toward something inherent in the biology of autism or its common co-occurring conditions. Dr. Lee Murray, a neurologist in Jackson, Tennessee, who was not involved in the research, said the strongest association appears in autistic people who also have an intellectual disability. He cautioned that autism encompasses a broad range of presentations and severity. “It certainly is an interesting correlation, although it does not imply that someone with autism is certain to develop Parkinson’s,” Murray said.
Murray also noted a diagnostic challenge. Autistic adults often have atypical movements, coordination difficulties, or repetitive behaviors that can look like parkinsonism to a clinician unfamiliar with autism. “Patients with autism can have atypical movements that can be misdiagnosed as Parkinson’s if the examiner is not accustomed to diagnosing it,” he said. Conversely, emerging neurological changes can be masked by lifelong motor differences, delaying recognition and care.
Implications for Clinical Monitoring and Care Planning
The study’s authors recommend establishing baseline motor assessments for autistic adults during midlife so that changes can be tracked over time. Wallace emphasized that clinicians, long-term care providers, and family caregivers should watch for emerging motor difficulties, including tremor, rigidity, slowed movement, and balance problems, so that appropriate interventions can begin as early as possible.
Murray recommended reviewing medications with patients’ physicians and, where possible, avoiding treatments that may produce Parkinson’s-like symptoms. For families navigating the care of an aging autistic relative, the findings add a new dimension to planning: the possibility of a neurodegenerative condition layered onto a lifelong neurodevelopmental one.
Future Research Directions and Policy Considerations
The researchers highlighted several gaps. Future studies will need to untangle the roles of genetics, lifestyle, and the specific biology of autism subtypes. Understanding why the risk appears highest in those with co-occurring intellectual disability could illuminate shared neurodevelopmental pathways. For now, the data establishes a clear epidemiological signal: autistic adults enter midlife and older age with a significantly higher burden of diagnosed parkinsonism, and the healthcare system will need to adapt its monitoring and care models accordingly.
Sources
- Autism
- People with Autism face higher risk of Parkinsons-related disorders – study
- Mind & Brain News
Photo: Hunt Han / Unsplash (Unsplash License)
