Certain antidepressants appear to decrease depression in people with Parkinson's disease without worsening motor problems, according to a study published in a recent online issue of Neurology, the medical journal of the American Academy of Neurology. It is estimated that of the nearly one million Americans who have Parkinson's disease, half suffer from depression.
"Depression dramatically impacts the quality of life for those who are living with Parkinson's disease," says co-principal investigator William McDonald, MD, JB Fuqua Chair for Late-Life Depression and Vice-Chair for Education, Emory University Department of Psychiatry and Behavioral Sciences. "This study offers hope because it shows that we can now safely treat depression in these patients without exacerbating other symptoms of Parkinson's."
Parkinson's disease is a chronic neurologic disorder known for causing tremor, slow movement, stiffness, balance problems and other motor difficulties.
"Though dealing with a chronic neurological condition is challenging on its own, people with Parkinson's are not depressed simply because they have Parkinson's," says Stewart Factor, DO, Vance Lanier Chair of Neurology at Emory University School of Medicine and clinical director of the Emory Movement Disorders Research Program. "The underlying disease process is the cause of the depression. If left untreated, depression can make the other symptoms of Parkinson's worse and very difficult to treat."
While older drugs used for depression in Parkinson's patients have been effective in treating depression, they have serious side effects. In this multi-center trial, called the Study of Antidepressants in Parkinson's Disease (SAD-PD), investigators aimed to determine if newer classes of antidepressants, which come with fewer side effects, could improve depression without worsening the motor symptoms that are often considered the hallmark of Parkinson's disease.
The drugs tested were paroxetine, a selective serotonin reuptake inhibitor (SSRI), and venlafaxine extended release, a serotonin and norepinephrine reuptake inhibitor (SNRI). The three-month clinical trial involved 115 people in various stages of Parkinson's disease who met the criteria for depression. Approximately one-third of the participants received paroxetine, one-third received venlafaxine and one-third received a placebo. The dosage of the drug was increased until the participant's depression was effectively treated.
On average, people receiving paroxetine had a 59 percent improvement, and those receiving venlafaxine a 52 percent improvement in their scores on the Hamilton Rating Scale for Depression. People who received a placebo had a 32 percent improvement. The drugs were generally well tolerated and did not lead to any worsening in motor functioning.
Emory served as one of 21 sites in the SAD-PD Study Group and was the lead recruiter, funded by National Institute of Neurological Disorders and Stroke. McDonald served as the co-principal investigator of the study, while Factor and Jorge Juncos, MD, Emory neurologist and associate professor of neurology at Emory University School of Medicine, served as Emory site investigators.