Drug treatment of non-motor symptoms in Parkinson's disease

Non-motor symptoms may considerably reduce parkinsonian quality of life, particularly in advanced stages of the disease. Autonomic features, such as seborrhoea, hyperhidrosis, orthostatic hypotension, excessive salivation, bladder dysfunction and GI disturbances, and neuropsychiatric symptoms, such as depression, sleep disorders, psychosis and dementia, appear in the course of Parkinson's disease. Pharmacotherapy of these non-motor symptoms complicates long-term antiparkinsonian combination drug therapy due to possible drug interactions, side effects and changes in metabolism. Moreover, antiparkinsonian compounds themselves contribute to the onset of these non-motor symptoms to a considerable extent. This complicates differentiation between the disease process itself and drug-related effects, thus influencing therapeutic options, which are often limited because of comorbidity and polypharmacy. Therefore, standardised recommendations are questionable, since drug tolerability and response differ between patients. Nevertheless, this review tries to provide a survey of possible therapeutic options for the treatment of the symptoms of Parkinson's disease other the dopamine-sensitive motor features.