People with depression are at significantly greater risk for Parkinson’s disease than the general population, and those with severe depression are especially vulnerable, according to an article published online recently by Neurology, the journal of the American Academy of Neurology.
Researchers reviewed data on more than 560,000 people in Sweden and determined that those with depression developed Parkinson’s at a rate nearly three times that of the other study participants. The more severe the depression, as measured by hospitalizations and other types of treatment, the higher the risk of Parkinson’s.
The authors said the findings suggest that depression is a warning sign or early phase of Parkinson’s, a nervous system disorder characterized by tremors, slurred speech, stiffness, an unusual gait and other symptoms. The findings come less than a year after the suicide of Robin Williams, who had battled depression and was in the early stages of Parkinson’s at the time of his death.
Carol Schramke, a clinical psychologist at Allegheny General Hospital who was not involved in the study, said the research underscores previously known links between psychiatric and neurological disorders.
“These are the kinds of things I tell the residents and medical students,” said Schramke, the hospital’s director of behavioral neurology. When a patient has depression or symptoms of depression, she said, there could be other brain-related problems involved — Parkinson’s perhaps but also Alzheimer’s, epilepsy or multiple sclerosis.
The possibility of a second disorder is particularly strong when a person’s first bout of depression comes later in life, she said.
The study’s findings did not surprise Audrey Daniels, a psychiatric nurse practitioner with Milestone Centers Inc., which provides services to people with mental-health disorders and intellectual and developmental disabilities.
“My own father had a form of Parkinson’s disease and suffered from depression I would say about 10 years prior to our being clear about exactly what was going on with him,” she said, citing the need to treat both disorders for maximum improvement of either one.
Currently there are no treatments to prevent or cure Parkinson’s. But if preventive measures one day are developed, Schramke said, the Swedish study identifies the type of patient who might be targeted for intervention.
While the findings aren’t entirely novel, the study advanced the link between depression and Parkinson’s in a powerful way, said Alessandro Di Rocco, professor of neurology and chief of the Division of Movement Disorders at New York University School of Medicine and NYU Langone Medical Center.
He said the large number of participants and long period over which participants were tracked — as long as 26 years — provided strong support for the findings.
He said the study highlighted the complex interplay between the disorders and the need to view Parkinson’s disease as having a continuum of symptoms.