Psychiatric aspects of Parkinson's disease

Recently, there has been much interest and rapid progress in understanding the neuropsychiatry of Parkinson's disease. This paper reviews the most important papers published during 2004 on dementia and cognitive impairment, depression and psychosis in Parkinson's disease.

Many new studies of cognitive impairment and dementia in Parkinson's disease have been published during 2004. Cognitive impairment has been demonstrated even during the first 1-2 years after onset of disease. Whereas executive and attentional impairment is typical, learning deficits occur early in some patients. Both functional and structural imaging suggest that in addition to fronto-subcortical deficits, temporal and parietal changes occur early as well. In the first large placebo-controlled trial, the cholinesterase inhibitor rivastigmine improved cognition, daily functioning and psychiatric symptoms without worsening of parkinsonism. The frequency and characteristics of depression, anxiety and hallucinations have been explored in several studies. Unfortunately, there is still little scientific evidence available to guide the treatment of these important aspects of Parkinson's disease, and adequately designed clinical trials are needed. Although subthalamic stimulation, in addition to improvement of movement, is frequently associated with some affective and cognitive improvement, permanent and significant worsening may occur in some. Future studies should aim at identifying at-risk patients, as well as identifying the optimal pharmacological and stimulation treatments for individual patients.

These findings provide a deeper understanding of the neurobiological substrate of cognitive impairment and dementia in Parkinson's disease, and provide new information regarding the assessment and management of dementia and other neuropsychiatric aspects of Parkinson's disease.