To explore the associations between depressive symptoms and cognition in patients with subjective cognitive impairment (SCI), mild cognitive impairment (MCI) and with Alzheimer's disease (AD).

286 Patients (60.8% females) with SCI (n=96), MCI (n=125), AD (n=65) from a University hospital-based memory clinic were compared in several tests of cognitive performance. Mean (SD) age 67.73 (7.2) and median (range) MMSE score 28 (16-30) and Cornell Scale for Depression in Dementia (CSDD) score 5 (0-20). The three groups were subdivided into those with and without depression as evaluated by CSDD (≥12). Cognitive functions were assessed in five domains (verbal, visuospatial, short-term memory, episodic memory and executive function) based on a comprehensive battery of neuropsychological tests.

A MANOVA on the five cognitive domains showed that depression vs. no depression differed significantly in the verbal (F (1,167) =4.24, p=.041) and executive (F(1,167)=17.87, p=.0001) domains. There was a significant interaction between diagnostic group, depression and cognitive domains F(2,167)=5.34, p=.006, due to a poorer performance in the executive domain for depressed MCI and AD patient compared with non depressed, but such an association was not found in SCI patients. Other markers of depression (history and current medication) did not change this pattern.

Depression is associated with executive function in MCI and AD patients.