As reported in Neurology Today’s by Olga Rukovets, the likelihood of developing a Parkinson’s disease-related movement disorder was two to three times higher in individuals with attention deficit-hyperactivity disorder (ADHD) than in those who did not have the diagnosis, and eight to nine times higher in those who were prescribed psychostimulants for the condition. Whether it is the underlying ADHD or the psychostimulants that cause the movement disorders is a question that requires further research, independent experts said.
A history of psychostimulant use for attention deficit-hyperactivity disorder (ADHD) was associated with a higher risk for a Parkinson’s disease (PD)-related movement disorder later in life, a retrospective review of data from a population-based database found.
The likelihood of developing a PD-related movement disorder was two to three times higher in individuals with ADHD than in those who did not have the diagnosis, and eight to nine times higher in those who were prescribed psychostimulants for the condition, the study authors reported in the December issue of Neuropsychopharmacology.
The study raises many questions, the lead study author Glen R. Hanson, DDS, PhD, vice dean and professor of pharmacology at the University of Utah School of Dentistry in Salt Lake City, told Neurology Today. “Amphetamines damage the same pathway that is involved in Parkinson’s — the nigrostriatal dopamine pathway… What is going on at the molecular level? Can we do something to stop it?”
Perhaps, he said, if there was an understanding of the connection between ADHD and PD or PD-like disorders, there would be hints for PD treatment, Dr. Hanson said. These types of experiments may be difficult to do in humans, he noted, so it will be important to look at animal models of hyperactivity in the future.
In the meanwhile, “neurologists could perhaps start to pay more attention to the medical history of patients from their youth and look to see if there could be some linkages with other childhood mental health disorders,” said Dr. Hanson, who has been studying the neurobiology of psychostimulants and their connection with PD for many years.
Indeed, given that three-quarters of children with ADHD are prescribed amphetamine or methylphenidate-based products for their ADHD symptoms—according to a recent report from the Centers for Disease Control and Prevention—the findings of the current analysis are “provocative,” pediatric neurologists not involved with the study told Neurology Today.
However, they advised caution in interpreting the results. The study authors have generated a hypothesis that should inspire more research, they said. For now, the findings underscore the need to discuss the risks and benefits of treatments for ADHD.
The study was funded by grants from the National Institute on Drug Abuse. Partial support for the database was provided by: the National Cancer Institute; the University of Utah’s Program in Personalized Health and Center for Clinical and Translational Science; and a National Center for Research Resources grant, with additional support from the Utah State Department of Health.
Glen R. Hanson, DDS, PhD, vice dean and professor of pharmacology