Characteristic clinical aspects of Parkinson patients with intellectual impairment.

The present study is based on the hypothesis that Parkinson's disease is not a single homogeneous entity and that parkinsonians with intellectual impairment are a distinct subgroup of the parkinsonian population. An assessment of cognitive functions was performed on 70 patients with Parkinson's disease and on 90 control patients. Analysis of their performances led to the division of parkinsonians into two subgroups: with and without neuropsychological impairment. Investigation of the clinical characteristics of the two subgroups showed that parkinsonians who are mentally impaired differ from other parkinsonians in that they present a more marked severity of the extrapyramidal syndrome with predominant bradykinesia and an earlier deteriorating response to levodopa treatment.