Dopamine receptor agonists and depression in Parkinson's disease.

Depression is one of the most common non-motor symptoms in Parkinson's disease (PD). It is associated with a more rapid progression of physical symptoms, greater decline in cognitive skills, and a poorer quality of life. Despite the high prevalence of depression and antidepressant use in PD, validated guidelines for the treatment of PD-associated depression (dPD) are lacking. Several methodological limitations have been recognized in the available studies examining the treatment of dPD. Some studies support a relevant role of the catecholaminergic systems in the pathogenesis of dPD. In open-label studies, the dopamine receptor agonists pramipexole and pergolide have shown antidepressant effects in PD patients. A placebo-controlled study of pramipexole in dPD is ongoing. The combined results of data from animal models and evidence in human studies support the strategy of dopaminergic stimulation as a treatment of depression. Treatment strategies for depressive symptoms in PD should include optimization of dopaminergic treatment prior to the addition of classic antidepressant drugs, thus reducing the risk of side-effects associated with multi-drug therapies.