Psychiatric aspects of Parkinson's disease--an update.

In patients with Parkinson's disease (PD) disturbances of mental state constitute some of the most difficult treatment challenges of advanced disease, often limiting effective treatment of motor symptoms and leading to increased disability and poor quality of life. This article provides an update on the current knowledge of these complications and the use of old and new drugs in their management. Mental state alterations in PD include depression, anxiety, cognitive impairment, apathy, and treatment-related psychiatric symptoms. The latter range from vivid dreams and hallucinations to delusions, manic symptoms, hypersexuality, dopamine dysregulation syndrome and delirium. While some of these symptoms may be alleviated by anti-parkinsonian medication, especially if they are off-period related, treatment-related phenomena are usually exacerbated by increasing the number or dosage of antiparkinsonian drugs. Elimination of exacerbating factors and simplification of drug regimes are the first and most important steps in improvement of such symptoms. However, the advent of atypical antipsychotics such as clozapine has dramatically helped the management of treatment-related psychiatric complications in PD. In patients with dementia associated with PD cognitive functioning and behavioural problems appear to respond to cholinesterase inhibitors, such as rivastigmine or donepezil. Depression is a common problem in early as well as advanced PD, and selective serotonin reuptake inhibitors, reboxetine, and tricyclic antidepressants have been reported to be effective and well tolerated antidepressants. Randomised, controlled studies are required to assess the differential efficacy and tolerability of antidepressants in patients with PD, including the newer antidepressants with serotonergic and noradrenergic properties.