Effects of the dopamine agonist pramipexole on depression, anhedonia and motor functioning in Parkinson's disease.

Depression affects approximately 45% of all patients with Parkinson's disease, reduces quality of live independent of motor symptoms and seems to be underrated and undertreated. Pramipexole shows D(3)- versus D(2)-receptor preference at cortico-frontal dopamine receptors and neurotrophic effects which seem to relate to its antidepressant and anti-anhedonic properties in Parkinson's disease and bipolar depression found in controlled studies. In the present study, effects of pramipexole were investigated under routine clinical conditions. Anhedonia was measured in patients with Parkinson's disease (n=657) using the self-rated Snaith-Hamilton-Pleasure-Scale (SHAPS-D), depression was assessed by the observer-rated Short-Parkinson's-Evaluation Scale (SPES). Anhedonia was present in 45.7% of all patients and in 79.7% of the depressed patients with Parkinson's disease. Mild depression was present in 47%, moderate to severe depression in 22% of the patients. At the end of the study period of 9 weeks on an average, the mean dosage of pramipexole was 1.0+/-0.6 mg/d (range 0.3 to 4.2). Frequency of depression (moderate to severe: 6.8%, mild: 37.6%) and anhedonia (25.5%) as well as motor deficits were significantly reduced during treatment with pramipexole. Drop-outs due to adverse events occurred in 3.5%. Future studies should investigate specificity of anti-anhedonic and antidepressive properties of pramipexole.