ADHD and Parkinson's disease: unraveling the link and implications for early intervention

Background: Attention deficit/hyperactivity disorder (ADHD) and Parkinson's disease (PD) are neurodevelopmental and neurodegenerative conditions respectively, involving alterations in dopamine signaling pathways. Emerging evidence suggests ADHD may be a potential risk factor for earlier PD onset. However, rigorous investigation of this association is still lacking. Aim: To examine the association between ADHD history and subsequent development of PD using a large retrospective cohort study. Methods: Patients aged ≥50 years were identified from clinician databases between 2010 and 2022 (N = 13,098) and categorized based on ADHD diagnosis. This retrospective cohort study employed Cox proportional hazards models to estimate hazard ratios (HR) for PD according to ADHD history, adjusting for demographic and clinical covariates. Kaplan-Meier survival analysis compared PD-free survival between ADHD and non-ADHD groups, while subgroup analyses explored the effects of ADHD medication use. Results: Individuals with a prior ADHD diagnosis had aa 33 % higher risk of PD (HR = 1.33, 95 % CI 1.12–1.58). Individuals with ADHD exhibited an earlier average age of PD onset. Kaplan-Meier curves demonstrated significantly poorer long-term PD-free survival among individuals with ADHD compared to those without. Subgroup analyses indicated that ADHD medication use did not significantly modify PD risk, as survival trends remained consistent across medicated and non-medicated groups. Conclusion: This study provides compelling evidence that ADHD influences PD risk and age of onset. Having ADHD history appears to independently impact long-term PD outcomes. The results highlight a need for tailored monitoring approaches for individuals with ADHD who may face an accelerated PD trajectory. Further research should investigate mechanisms and preventive strategies for high-risk neurodevelopmental populations.