Does ADHD Cause Parkinsonism?
No, ADHD itself does not cause parkinsonism, but emerging evidence suggests individuals with ADHD may face a modestly increased risk of developing Parkinson's disease later in life, with a 33% higher risk and earlier age of onset compared to those without ADHD. 1
Understanding the Distinction
ADHD and parkinsonian syndromes are fundamentally different conditions with distinct pathophysiology:
Parkinsonian syndromes are characterized by motor symptoms including tremor, rigidity, postural instability, and bradykinesia, with Parkinson's disease being the most common cause, typically presenting with peak onset between ages 60-70 years. 2
ADHD is a neurodevelopmental disorder involving executive deficits in cognitive domains such as working memory, inhibitory control, vigilance, and planning, with abnormalities in frontostriatal, frontoparietal, and ventral attention networks. 2
ADHD symptoms must have onset before age 12 and persist across multiple settings since childhood, whereas Parkinson's disease develops later in life through progressive degeneration of dopaminergic neurons in the substantia nigra. 3
Emerging Evidence of Association
While ADHD does not directly cause parkinsonism, recent research reveals a concerning temporal relationship:
A 2025 retrospective cohort study of 13,098 patients aged ≥50 years found that individuals with prior ADHD diagnosis had a 33% higher risk of developing Parkinson's disease (HR = 1.33,95% CI 1.12-1.58), with significantly earlier average age of PD onset. 1
An earlier 2018 study demonstrated that ADHD patients had a 2.4-fold increased risk of basal ganglia and cerebellum diseases (95% CI: 2.0-3.0), with ADHD patients prescribed psychostimulants showing an 8.6-fold increased risk between ages 21-49 years. 4
Critical caveat: The association between ADHD patients on psychostimulants and higher risk of basal ganglia diseases likely reflects a more severe ADHD phenotype rather than a direct causal effect of stimulant medications themselves. 4
Genetic and Mechanistic Considerations
A 2017 genetic study found no significant genetic association between nine ADHD candidate SNPs and Parkinson's disease after correction for multiple testing, suggesting that ADHD genetic variants do not substantially contribute to PD pathogenesis. 5
Both conditions involve dopaminergic pathway alterations, but through different mechanisms: ADHD involves dysregulated dopamine signaling in frontostriatal circuits, while Parkinson's disease results from progressive loss of dopaminergic neurons in the substantia nigra. 2, 4
A 2007 case-control study of 92 PD patients found higher scores for attention deficit and hyperactivity symptoms in childhood compared to controls, but average scores were far below the threshold for childhood ADHD diagnosis, and no evidence of psychostimulant exposure was found. 6
Clinical Implications
For patients with ADHD, this does not warrant withholding evidence-based treatment:
Stimulant medications remain first-line therapy with 70-80% response rates and the largest effect sizes for ADHD treatment. 7
The American Academy of Pediatrics emphasizes that untreated ADHD is associated with increased risk for early death, suicide, psychiatric comorbidity, lower educational achievement, and incarceration—risks that far outweigh theoretical long-term concerns. 3
The association observed in research may reflect disease severity or shared underlying vulnerability rather than medication effects, and should not alter standard treatment algorithms. 4
Monitoring approach for older adults with ADHD history:
Individuals with ADHD history who reach age 50+ may benefit from heightened clinical vigilance for early parkinsonian signs, given the 33% increased risk and earlier onset pattern. 1
Standard ADHD management following chronic care model principles with ongoing monitoring for comorbid conditions remains appropriate. 3