Treatment of Parkinson's disease. Psychological disorders: striking a balance in order to optimise antiparkinsonian treatment.

Parkinson's disease is frequently associated with psychological disorders, especially depression, psychotic disorders, and dementia. We examined the management of psychological disorders in Parkinson's disease, including the use of psychotropic drugs, by reviewing the literature using the standard Prescrire methodology. About one-third of patients with Parkinson's disease experience visual hallucinations. Other hallucinations and delusions can also occur. Dose reduction or withdrawal of certain antiparkinsonian drugs sometimes improves psychotic disorders, providing an acceptable level of symptom control. Clozapine is effective and does not worsen parkinsonian symptoms, but it carries a risk of severe adverse effects, including agranulocytosis. Other neuroleptics are ineffective or worsen motor status. Mood disorders and depression are frequent during the course of Parkinson's disease. Pramipexole, an antiparkinsonian dopamine agonist, improved depressive symptoms in patients with Parkinson's disease in one trial. Its main adverse effects are ocular disorders. Several trials have shown that some tricyclic antidepressants improve depression in Parkinson's patients, but these drugs can worsen cognitive status and cause postural hypotension. Data on selective serotonin reuptake inhibitor antidepressants (SSRIs) are unconvincing. A meta-analysis of three trials showed that treatment withdrawals due to adverse events were similarly frequent with tricyclics and SSRIs. Dementia is frequent in end-stage Parkinson's disease. When severe cognitive disorders occur, it is advisable to withdraw any drugs capable of worsening the situation, especially drugs with antimuscarinic effects and benzodiazepines. Cholinesterase inhibitors have a negative harm-benefit balance in this setting. When a Parkinson's patient presents with a psychological disorder, the first step is to optimise antiparkinsonian treatment by striking a balance between motor control and psychological adverse effects. In the few situations in which drug treatment is likely to be beneficial, it should be remembered that psychotropic drugs are at best only moderately effective and should be used with care, monitoring patients for adverse effects.