A US study has found that people with Attention-Deficit Hyperactivity Disorder (ADHD) may have an increased risk of developing Parkinson's.
What the study found
Researchers at the University of Utah in the US studied healthcare records from over 31,769 people diagnosed with ADHD and compared these to records of 158,790 people without the disorder of matched age and gender.
They found that:
- people with ADHD were more than twice as likely to be diagnosed with Parkinson's
- people with ADHD who were prescribed medication for the condition were 4 times as likely to be diagnosed with Parkinson's
The main medications used to treat ADHD are stimulants that are closely related to amphetamines.
Other studies have previously shown that taking amphetamines can increase the risk of developing Parkinson's in later life, so this study may add to this evidence.
the jury's out
Our Deputy Director of Research, David Dexter, comments:
"While this study reveals a number of interesting possibilities, it's important to stress that the increased risk identified is relatively small in people with ADHD, rising more markedly when individuals with the disorder take stimulant medications, such as Ritalin.
"Even in the 4,960 records of people with ADHD who were prescribed stimulant medications in this study, only 19 were subsequently diagnosed with Parkinson's.
"We need to see larger studies in other populations before we can be sure that the connection is real, and to understand what is driving the relationship between the 2 conditions."
The results are available online on September 12 in the journal Neuropsychopharmacology.