Summary: A large, population-based Swedish study found that people diagnosed with autism spectrum disorder (ASD) face a substantially higher risk of developing Parkinson’s disease at a young age. Tracking more than two million individuals, researchers observed that autistic people were roughly four times more likely than others to receive a Parkinson’s diagnosis before age 50.
The investigators suggest the association may reflect overlapping biology, particularly involving dopamine pathways that influence both movement and social behavior. The increased risk persisted even after accounting for socioeconomic factors, family history, psychiatric comorbidity and use of psychotropic medications, indicating a possible intrinsic link between ASD and early-onset Parkinson’s disease.
Key facts:
- Markedly higher risk: Individuals with ASD experienced about a fourfold increase in early-onset Parkinson’s disease compared with those without ASD.
- Biological hypothesis: Disruption of dopamine-related brain systems is a plausible shared mechanism.
- Robust association: After adjusting for antidepressant or antipsychotic use and for depression, the association remained elevated—approximately double the risk.
Source: Karolinska Institutet
Overview
Researchers at Karolinska Institutet published an analysis in JAMA Neurology examining whether a diagnosis of autism spectrum disorder is associated with later development of Parkinson’s disease. The study used nationwide Swedish registry data covering people born between 1974 and 1999 and followed them from age 20 through the end of 2022.
The investigators explored links between ASD, a neurodevelopmental condition that affects cognition, social communication and behavior, and Parkinson’s disease, a neurodegenerative disorder characterized by motor symptoms such as tremor, rigidity and slowed movement.
Dopamine-related systems may be implicated
Participants with an ASD diagnosis had a substantially higher incidence of early-onset Parkinson’s disease compared with those without ASD. This relationship remained after statistical adjustment for sex, socioeconomic status, family history of psychiatric disorders or Parkinson’s disease, and other measured factors.
The study authors propose that dysfunction in dopamine neurotransmission could be a shared element. Dopamine is central to motor control and is also implicated in social behavior; degeneration of dopamine-producing neurons is a hallmark of Parkinson’s disease, and previous research has suggested possible dopamine-related differences in autism that merit further investigation.
“We hope that our results will eventually help to bring greater clarity to the underlying causes of both ASD and Parkinson’s disease,” says Weiyao Yin, the study’s first author.
Clinical implications
People with ASD frequently experience depression and are more likely to be prescribed antidepressants or antipsychotic medications. Antipsychotics can produce Parkinsonism-like side effects, so the authors examined whether medication use or psychiatric comorbidity explained the observed association.
Adjusting for depression, antidepressant use and antipsychotic exposure reduced the strength of the association but did not eliminate it: the elevated risk remained approximately twofold after these factors were taken into account. This suggests that medication effects and comorbid mental health conditions contribute to, but do not fully explain, the increased Parkinson’s risk observed among people with ASD.
The researchers emphasize that their analysis focused on early-onset Parkinson’s disease (diagnoses before age 50). Because the study cohort’s median age at the end of follow-up was 34 years, overall Parkinson’s cases were rare. Additional research is needed to determine whether the higher risk persists into older adulthood.
“Healthcare providers should maintain long-term follow-up for individuals with ASD, who often have multiple comorbidities and higher rates of psychotropic medication use,” says Sven Sandin, the study’s senior author. He also notes that Parkinson’s disease before age 50 remains uncommon, including among those with autism.
Funding and disclosures
The study received principal funding from the Simons Foundation and the Swedish Research Council. Two authors reported receiving funding or fees from pharmaceutical companies unrelated to this work; the published paper lists detailed disclosures.
About this autism and Parkinson’s disease research news
Author: Press Office
Source: Karolinska Institutet
Contact: Press Office – Karolinska Institutet
Image: The image is credited to Neuroscience News
Original research: Closed access. “Risk of Parkinson Disease in Individuals With Autism Spectrum Disorder” by Weiyao Yin et al., JAMA Neurology.
Abstract (rephrased)
Importance
Prior studies have suggested possible biological connections between neurodevelopmental disorders such as ASD and Parkinson’s disease, but large longitudinal investigations addressing the subsequent risk of Parkinson’s disease after ASD have been limited.
Objective
To evaluate whether ASD is associated with an increased future risk of Parkinson’s disease.
Design, setting and participants
This nationwide, population-based cohort study used Swedish national registers. It included all individuals born between 1974 and 1999 with follow-up from age 20 to December 31, 2022, and complete covariate information. The analysis was completed in August 2024.
Exposures
ASD diagnoses recorded in the National Patient Register were treated as time-varying exposures.
Main outcomes and measures
Parkinson’s disease diagnoses were identified through the National Patient Register through 2022. Incidence rate ratios from Poisson regression estimated relative risk, with attention to potential modifiers including preterm birth, depression, antidepressant use, and antipsychotic exposure over time.
Results
The cohort comprised 2,278,565 individuals (median age at exit 34 years). Parkinson’s disease occurred in 438 of 2,226,611 individuals without ASD and in 24 of 51,954 individuals with ASD, corresponding to a roughly fourfold increased relative risk. Adjustments for demographic and familial factors produced similar estimates. Depression and antidepressant use were independently associated with increased Parkinson’s risk, and antipsychotic exposure reduced but did not fully explain the association between ASD and Parkinson’s disease.
Conclusions and relevance
ASD was linked to an elevated risk of early-onset Parkinson’s disease even after accounting for depression, antidepressant use and antipsychotic exposure. These findings point to a potential shared etiology between neurodevelopmental conditions and Parkinson’s disease and underscore the importance of long-term neurological monitoring in people with ASD.