Idiopathic Parkinson's disease: revised concepts of cognitive and affective status

Assumptions regarding increased risk of dementia in Parkinson's disease and of depression mimicking the endogenous form are reviewed and challenged from the perspectives of recent findings in both the neuropsychological and anatomical domains. Evidence suggests that depression, while frequent, behaviourally resembles the reactive variety and that selective impairment of cognitive functions considered to depend upon the integrity of the frontal lobes accompanies this disorder. In this regard, it is speculated that the cognitive alterations seen in non-demented parkinson patients are the consequences of dysfunction of the caudate nucleus which contributes significantly to the normal activities processed through the frontostriate "complex loop".