Tricyclic Superior to SSRI in Treatment of Depression in Parkinson's Disease
Posted Jun 22 2009 11:59pm
From Geriatric Pharmacy Intern, Arathi Reddy, PharmD(c) Palm Beach Atlantic University School of Pharmacy
Parkinson’s disease (PD) affects up to 1 million people each year in the United States and is a movement disorder that impairs motor skills, speech, and other function. About 50 % of patients diagnosed with Parkinson’s have depression as well, a co-morbidity, which is associated with poorer outcomes due to a drastic decline in quality of life and a faster progression of physical symptoms. Together these conditions in the elderly population can quickly result in tremendous patient suffering leading them to being put in a nursing home, and therefore proper treatment is crucial. Although the use of tricyclic antidepressants (TCA), a class of antidepressants, is limited in the elderly particularly due to a strong side effect profile including anticholinergic activity, recent studies have indicated that TCA use in PD may be superior to SSRIs, another class of antidepressants. A randomized, controlled trial in 2008 compared nortriptyline, a TCA, and paroxetine, an SSRI, and placebo, among 52 patients with PD and depression. Based on the results of the study, the older antidepressant, nortriptyline, outperformed both placebo and paroxetine in terms of the HAM-D scale, a rating scale used to assess symptoms of depression. Both drugs were well tolerated in the study with an equal number of dropouts in each treatment group, although there were slightly higher rates of mild constipation, dry mouth, and dizziness with nortriptyline (anticholinergic side effects). Based on this preliminary study, research should be further conducted to analyze the mechanism of depression in PD, since the general population does respond better to SSRIs, as opposed to TCAs. In fact, that is why it was found that 63% of patients with PD and depression were on SSRIs and only 7% were taking older tricyclic antidepressants. PD is characterized by a decline of dopamine in the brain, but there may also be a resulting problem with the processing of norepinephrine. Therefore it may be that the drug which affects both norepinephrine and serotonin, a dual reuptake inhibitor, is superior to newer drugs that affect only serotonin. However, ongoing trials are being conducted and clinicians should not make therapeutic changes yet as larger longer trials may produce similar or different results.