Could Autism Be a Predictor of Early-Onset Parkinson Disease?

Autism spectrum disorder (ASD) is associated with increased risk for Parkinson disease (PD), with the association persisting after adjustments for depression, antipsychotic exposure, and antidepressant use. The findings of this study were published in JAMA Neurology.

ASD is a lifelong disability affecting 2% of children worldwide. As more children with ASD now progress to older adulthood, more research is needed on long-term conditions, specifically in the onset of other conditions with higher genetic predispositions like PD. Currently, there is a lack of robust epidemiological studies assessing the relationship between ASD and PD.

Researchers from the Karolinska Institutet sourced data for this study from national databases in Sweden. All individuals (N=2,487,166) born in Sweden between 1974 and 1999 were evaluated for ASD in childhood and PD from 20 years of age through 2022.

The final cohort comprised 2,278,565 individuals (median age at exit, 34; women, 48.6%).

The chart below compares key demographic and medication-related characteristics between individuals with and without an ASD diagnosis.

Characteristic	With ASD (N=51,954)	Without ASD (N=2,226,611)
Antidepressant Use	46.7%	8.7%
Antipsychotic Use	31.5%	3.1%
Men	61.1%	51.2%
Born Full Term	64.8%	68.4%

A total of 24 individuals with ASD and 438 without ASD developed PD in adulthood, at rates of 3.86 and 1.32 per 100,000 person-years (py), respectively. For idiopathic PD, the rate in ASD was 1.61 per 100,000 py and without ASD was 0.71 per 100,000 py.

In the fully adjusted model, ASD was associated with increased risk for PD (relative risk [RR], 4.59; 95% CI, 3.01-7.01) and idiopathic PD (RR, 3.70; 95% CI, 1.92-7.11).

The risk for PD was increased:

• 4.5-fold in those with ASD (RR, 4.43; 95% CI, 2.92-6.72),
• 2-fold in those with depression and antidepressant use (RR, 2.01; 95% CI, 1.40-2.88), independent of ASD, and
• 6-fold independently associated with antipsychotic exposure (RR,6.34; 95% CI, 3.83-10.48).

Study limitations included the limited follow-up period, inability to exclude the influence of residual confounding of increased medication use and healthcare services of individuals with ASD, mischaracterization of parkinsonian signs as ASD-related stereotypes, and the small number of PD cases, affecting the power of this study, especially in subgroup analyses.

 “These findings suggest a potential shared etiology between neurodevelopmental disorders and PD. Potentially, a heightened awareness of long-term neurological conditions in individuals with ASD may be warranted,” the researchers concluded.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.