Nondemented Parkinson disease patients: is cognitive performance associated with depressive difficulties?

Poorer cognitive performance in depressed versus nondepressed nondemented Parkinson disease (PD) patients has been suggested.

Investigate the relationship between level of depression assessed on a depression-measuring scale and cognitive performance in nondemented PD patients.

Nondemented idiopathic PD patients (n=110) were evaluated for the level of depression [cognitive-affective items of the Beck's Depression Inventory (BDI)] and performance in a set of tests evaluating cognitive domains typically affected in PD (memory, visuospatial, and executive functions).

Multiple regression analysis of BDI scores demonstrated independent association of poorer cognitive performance, more severe parkinsonism, and poorer education with higher BDI scores. The association between poorer cognition and higher BDI scores was conditional on education, that is, was apparent only in less educated patients (<12 y of formal education).

Poorer cognitive performance in nondemented idiopathic PD patients is associated with more severe depressive difficulties. Poorer education is also associated with more severe depression. Education modifies the cognition-depression relationship.