Depression also a problem in patients with Parkinson's
While Parkinson's disease typically brings to mind symptoms such as tremors and slow movement, researchers have found that nearly half of all Parkinson's patients also suffer from depression. While it might seem natural that someone who has a disease such as Parkinson's might become depressed, it's not so simple, says neurologist Irene Richard, M.D., of the University of Rochester Medical Center.
"Many patients assume that's it's normal to feel this way. They might say, 'If you had Parkinson's disease, you'd feel this way too.' That's not true. If you treat the depression, they'll still have the other symptoms of the disease, but they feel better. It's one aspect of the disease that may be very treatable," says Richard.
"People diagnosed with other serious diseases that may also be disabling, such as rheumatoid arthritis, aren't nearly as likely to become depressed."
Richard and co-author William McDonald, M.D., a psychiatrist at Emory University, discussed the links between depression and movement disorders like Parkinson's disease in a review article in the August 24 issue of the journal Neurology. In an article titled, "Can 'blue' genes affect mood and movement?" the two noted that a team from Columbia University has linked a gene known to cause a movement disorder known as dystonia with a type of early-onset depression. Now they and other physicians around the country are exploring possible links between mood and movement in other disorders such as Parkinson's disease.
Of Parkinson's patients who become depressed, about half have "major" depression that has a significant impact on their lives, while others have milder forms of depression that are still distressing.
"There's a huge amount of suffering out there due to the depression that comes so frequently as part of Parkinson's disease," says Richard, who is an expert on the psychiatric aspects of the disease. Patients who have lost the pleasure they once took in activities or hobbies, or who are having difficulty sleeping or have a poor appetite, have common symptoms of depression.
"The depression is part of the illness, not simply a reaction to the disease. We've found that if a physician brings up the topic, patients will be honest and will discuss their depression, but oftentimes they won't bring it up themselves. But depression is the number-one factor responsible for poor quality of life among these patients. We need to educate physicians to ask about this in their patients with Parkinson's disease," says Richard, an associate professor of Neurology and Psychiatry.
Doctors estimate that about 1 million people in North America have Parkinson's disease, which targets a small group of cells in a part of the brain known as the substantia nigra that produce a chemical called dopamine. The loss of these brain cells results in abnormal signals to other parts of the brain, which Richard says appears to influence a person's mood. In addition, the disease also affects cells that produce brain chemicals such as serotonin and norepinephrine, which can play a role in depression.
Richard and McDonald are leading a national research study to test the effectiveness of anti-depressants in treating some of the symptoms of Parkinson's disease. The study will evaluate common anti-depressant medications paroxetine (brand name Paxil) and venlafaxine (brand name Effexor) at treating the depression that patients experience. Richard says that until now, there hasn't been a large placebo-controlled study to see how well anti-depressant medications actually work in patients with Parkinson's. The disease wreaks havoc in the brain and may cause such medications to work differently than they do in healthy people.
The study will include 228 patients at 15 sites around the nation. The four-year, $4 million study is being funded by the National Institute of Neurological Disorders and Stroke.