Study links this disorder and its meds to Parkinson’s

A new study linking attention-deficit hyperactivity disorder (ADHD) drugs and Parkinson’s disease could cause prescribers to re-think prescribing the medications.

In a new study, published in the September 12 issue of Neuropsychopharmacology, researchers found that ADHD patients were more than twice as likely to develop early onset (aged 21 to 66 years) Parkinson’s and Parkinson-like diseases compared to non-ADHD individuals of the same gender and age.

The estimated risk was 6 to 8 times higher for ADHD patients prescribed the stimulant meds methylphenidate (Ritalin, Concerta, and other brand names), mixed amphetamine salts (Adderall) and dexmethylphenidate (Focalin).

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“Parkinson’s disease is commonly thought of as a neurodegenerative disease associated with aging,” said Glen Hanson, DDS, PhD, senior author of the paper and professor of Pharmacology and Toxicology and School of Dentistry at the university of Utah Health, in a statement from the university. “This may be the first time where a childhood disease and its treatment may be linked to a geriatric expression of neurodegenerative disorder.”

“The study could lead some physicians taking a pause before writing a prescription for stimulant-based ADHD drugs. Parents and adult patients may be asking many more pointed questions about whether the medications are necessary,” John Matthews, strategy leader for Healthcare & Life Sciences at KPMG, told FormularyWatch.

While it is possible the study’s findings could dampen sales of Ritalin and other ADHD drugs, additional studies will be required before there is a dramatic swing in prescribing trends, according to Matthews.

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“There has been a great deal of attention dedicated to how frequently these medications are prescribed and the necessity for certain patients to use them,” Matthews said. “Borderline cases are where there can be an impact on prescribing. For example, the risk might not be worth it for an adult using ADHD drugs for weight control or the child that might be able to function in class without the medication.”

The authors agree that future studies are needed to reach a more definitive conclusion. Patients with a more severe type of ADHD may inherently be at an increased risk of motor neuron diseases like Parkinson’s, and the results may or may not be a direct result of the stimulant medication, according to the U of U statement.

“The jury is still out,” said Karen Curtin, PhD, first author on the study and associate professor of internal medicine at University of Utah Health. “The increased risk we observed in people could be linked to having ADHD itself or perhaps a more severe form of ADHD, which may be more likely to be treated with medications.”

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