Depression affects up to half of people with Parkinson's disease. A study of 52 people with Parkinson's disease and depression compared the effects of nortriptyline (an older, tricyclic antidepressant), paroxetine (a selective serotonin reuptake inhibitor or SSRI) and a placebo. The study found that the participants who took nortriptyline were five times more likely to see an improvement in their depression as those who took paroxetine. SSRIs affect the level of serotonin in the brain, whereas tricyclic antidepressants affect the level of norepinephrine. However, tricyclic antidepressants can lead to an increased risk of overdose and death due to toxic effects on the heart and brain.
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