Parkinson Disease and ADHD: What’s the Connection?

Attention-deficit/hyperactivity disorder (ADHD) involves dysregulated dopaminergic pathways, and as such, dopaminergic agents such as amphetamine and methylphenidate are prescribed to treat the condition. Because little is known about the long-term consequences of either ADHD or its treatment, researchers designed a retrospective cohort study to determine if either affects the risk of diseases of the basal ganglia and cerebellum, including Parkinson disease (PD).

Using statewide Utah medical records from 1996 to 2016, the authors identified 31,769 adult patients with a diagnosis of ADHD and 158,790 random sex-matched and age-matched patients without an ADHD diagnosis. The participants had no history of PD or parkinsonian diseases, basal ganglia diseases, essential tremor, or substance abuse. The outcomes measures were time to diagnosis of basal ganglia and cerebellum diseases or death.

The findings showed that patients with ADHD had a 2.4-fold increased risk of basal ganglia and cerebellum diseases than  control participants after controlling for sex, age, tobacco use, and psychotic conditions. They found that the 4960 ADHD patients who had been prescribed psychostimulants had an 8.6-fold higher risk of developing Parkinson-like diseases between the ages of 21 and 49.

The authors noted that the association of ADHD patients who had been prescribed psychostimulants with a higher disease risk “may reflect a more severe ADHD phenotype rather than a direct association between prescribed stimulant use and basal ganglia or cerebellum disorders.” They called for future studies to assess and stratify patient risk so as to inform treatment.

—Michael Gerchufsky

Reference:

Curtin K, Fleckenstein AE, Keeshin BR, et al. Increased risk of diseases of the basal ganglia and cerebellum in patients with a history of attention-deficit/hyperactivity disorder [published online September 12, 2018]. Neuropsychopharmacology. https://www.nature.com/articles/s41386-018-0207-5. Accessed September 12, 2018.