ABSTRACT
Parkinson's disease (PD) is a complex disorder with neurological and psychiatric components. The maintenance of mental health in PD may be more important than the physical state. The complexity of the psychiatry of PD is a manifestation of the heterogeneity of PD itself. Psychometric testing, electrical measurement and imaging techniques can be used in the assessment of cognitive and psychiatric processes in PD. Patients with PD demonstrate slowing of movement, and in addition show variable degrees of slowing of thought and speech. The effects of treatment on cognition are confusing. Levodopa would be expected to improve function mediated by dopaminergic pathways, but the effects are difficult to separate from the effects of disease severity and motor performance. The age-specific prevalence of dementia in the normal population increases with increasing age. The development of PD dementia is associated with subcortical loss of ascending projections from brainstem nuclei and disconnection of prefrontal connections to the caudate nuclei.
