New research warns that people with ADHD (attention-deficit/hyperactivity disorder) may be twice as likely to develop Parkinson’s.
Researchers studied 200,000 Utah residents born between 1950 and 1992. The onset of Parkinson's was tracked up until the age of 60. Roughly 32,000 of the participants had previously been diagnosed with ADHD.
They found that compared to those with no history of the disease, ADHD patients were 2.4 times more likely to develop Parkinson’s disease-like disorders prior to the age of 50 to 60. This discovery was true even after accounting for several factors, such as smoking, drug and alcohol abuse, and other psychiatric disorders.
Additionally, ADHD patients with a record of being treated with amphetamine-like drugs, such as Ritalin, were between eight and nine times more likely to develop an early onset form of Parkinson’s.
Senior study author Glen Hanson believes the link between ADHD patients and the development of Parkinson’s may source back to a functional disorder of central nervous system dopamine pathways.
"The drugs used to treat ADHD apparently work because of their profound effects on the activity of these dopamine pathways," Hanson stated. Theoretically, the treatment itself might trigger a metabolic disturbance, promoting dopamine pathway degeneration and, ultimately, Parkinson's, he explained.
Despite the connection, researchers are still not able to determine whether the increased risk associated with stimulant use is due to the presence of the drug or the severity of the ADHD, given that those treated with ADHD drugs tend to have more severe forms of the disorder.
The results are available online on September 12 in the journal Neuropsychopharmacology.