Depressive symptoms in Parkinson disease correlate with impaired global and specific cognitive performance

Consecutive patients in a Movement Disorders Center with Parkinson disease (PD) were offered to undergo complete neuropsychological testing and to complete the Beck Depression Inventory (BDI), regardless of their cognitive and behavioral status. A total of 82 patients were included in this cross-sectional study and had a mean age of 67.7 years, formal education of 14.8 years, PD duration of 101 months, Unified Parkinson Disease Rating Scale-Motor ''off'' score of 36.96, Mini-Mental State Examination (MMSE) score of 27.8 (range 19-30), and BDI score of 10.23 (SD 8.65). Beck Depression Inventory scores did not correlate with disease duration or motor scores but inversely correlated with the MMSE scores (r = -0.40; P < .001) and total Dementia Rating Scale (DRS) scores (r = -0.33; P < .01). Using a univariate regression analysis controlling for age, gender, education, and total Unified Parkinson Disease Rating Scales (UPDRS) score, the BDI scores had a significant and unique relationship with MMSE scores. However, when the BDI scores were correlated with specific cognitive domains, only the Boston Naming Test and the Hopkins Verbal Learning Test (HVLT) delayed recall remained significant after Bonferroni correction. Similarly, when comparing the cognitive performance of patients with PD who scored >14 on the BDI versus those who scored <14, only the mean score of the Boston Naming Test was different between the 2 groups. Our study shows that while depressive symptoms correlated with global cognitive performance, naming, verbal memory, and language are the most susceptible cognitive domains affected with depressive symptoms.