People with Autism face higher risk of Parkinsons-related disorders – study

Autistic adults aged 45 and over were diagnosed with parkinsonism at higher rates than other adults, according to a large US study.

An analysis of Medicare and Medicaid claims data covering nearly 57 million Americans aged 45 and older between 2017 and 2019 found higher rates of Parkinson’s-related movement disorders among people with autism and intellectual disabilities.

Parkinsonism refers to a group of neurological conditions characterised by movement symptoms, including tremors, muscle stiffness, balance difficulties and slowed movement.

The prevalence of parkinsonism was approximately 1.57 per cent in the general population control group, compared with 3.83 per cent among adults with autism alone.

The figure rose to 4.32 per cent among those with an intellectual disability alone and 4.86 per cent among people with both autism and an intellectual disability.

These figures describe prevalence, the proportion of people with a recorded diagnosis.

Greg Wallace, lead author and professor in the Department of Speech, Language and Hearing Sciences at The George Washington University, said the findings provided new evidence about movement disorders in autistic adults.

He said: “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.

“It is therefore important for clinicians to establish clear baselines of motor skills and challenges during adulthood that can be tracked over time.”

The study also examined incidence, which measures newly diagnosed cases over time. Researchers said this was the first study to track incidence rates of parkinsonism among older autistic adults.

Researchers also investigated whether antipsychotic medications, which can cause Parkinson’s-like movement symptoms, could explain the association.

Higher rates of parkinsonism persisted among autistic adults and those with intellectual disabilities after people taking these medications were excluded.

Previous research had suggested a link between autism and movement difficulties later in life, although it remained unclear whether these reflected lifelong motor challenges or medication side effects.

Dr Lee Murray, a neurologist based in Jackson, Tennessee, who was not involved in the research, said the findings helped clarify earlier evidence suggesting an association between autism and Parkinson’s disease.

He explained that antipsychotic medications can produce symptoms resembling Parkinson’s disease, including resting tremors, stiffness, a shuffling gait and changes in posture or voice.

These medication-related symptoms have a different underlying cause from Parkinson’s disease itself.

Murray said the strongest association appeared among autistic people who also had an intellectual disability.

He cautioned that autism encompasses a broad range of symptoms and severity, and the findings should not be taken to mean that people with milder presentations necessarily face a significantly higher risk of Parkinson’s disease.

He said: “It certainly is an interesting correlation, although it does not imply that someone with autism is certain to develop Parkinson’s.”

The researchers acknowledged several limitations, particularly the study’s reliance on Medicare and Medicaid billing records.

Errors in diagnostic coding and differences in how healthcare providers identify conditions could affect the accuracy of recorded diagnoses.

The data also prevented researchers from assessing the severity of movement symptoms or examining potential influences such as lifestyle, genetics and family history.

Because the study only included adults enrolled in public insurance programmes, its findings may not fully represent people who rely exclusively on private health insurance.

Movement differences already associated with autism could also complicate the identification of new neurological conditions.

Some autistic people experience coordination difficulties, repetitive behaviours or executive functioning challenges, which can make emerging movement problems harder to recognise or lead to misdiagnosis.

Murray said: “Patients with autism can have atypical movements that can be misdiagnosed as Parkinson’s if the examiner is not accustomed to diagnosing it.”

He also recommended reviewing medications with patients’ physicians and, where possible, avoiding treatments that may produce Parkinson’s-like symptoms.

The researchers emphasised the importance of monitoring changes in movement among middle-aged and older autistic adults.

They said clinicians, long-term care providers and family caregivers should watch for emerging motor difficulties so that appropriate interventions can begin as early as possible.