Depression impairs executive functioning in Parkinson disease patients with low educational level

To assess overall cognitive performance and executive functioning of nondemented Parkinson disease (PD) patients, and the influence of variables such as depression and education on cognition.

Cognitive dysfunction in PD is common even in early stages. Different variables have been identified as potential risk factors for cognitive decline in PD. Some of these variables, such as depression and educational level, are complexly interrelated.

Eighty-two (male:female 52:30) subjects underwent clinical assessment which included the Unified Parkinson's Disease Rating Scale, Schwab-England Scale, Hoehn-Yahr Scale, Beck Depression Inventory, the Frontal Assessment Battery (FAB), and the Mini-Mental State Examination (MMSE).

Patients with higher education, younger age, and who had a younger age at disease onset performed better on both the FAB and MMSE. Severity of disease correlated with worse cognitive performance. Performance on the FAB, but not the MMSE, worsened with increased severity of depressive symptoms. When patients were divided into groups with lower (< or =4 y of schooling) and higher (> or =5 y of schooling) education, the FAB and Beck Depression Inventory correlated negatively only in the group with lower educational level.

Patients with PD present with cognitive impairment even when nondemented. Depression may exacerbate executive dysfunction, especially in subjects with lower educational level.