Cognitive Reserve in Major Depression–Associations with Cognitive Status, Age, Education, Personality, and Depression Severity

Cognitive reserve (CR) is understood as a latent potential underlying the flexible adaptation to mental challenges. By optimizing cognitive performance, it can be used to cope with high task demands. This study examines CR in 40 inpatients with unipolar depression compared to 24 healthy control subjects. The size of CR was assessed by calculating the maximal performance improvement over retesting with a digit symbol substitution task. Furthermore, the relation between CR, cognitive status, age, education, and the personality traits Openness for experience and Neuroticism was explored. CR did not differ significantly between controls and the whole group of depressed patients. However, patients who displayed cognitive deficits in one–time neuropsychological testing (50%) showed a lower CR than controls while patients without deficits showed a marginal higher CR. In patients, CR was positively associated with attention, short term memory, and openness for experience. In controls, CR was relatively independent from cognitive status but showed a negative association with age. Our results support the idea that subgroups of patients can be differentiated through cognitive status as well as CR. Furthermore, the marginal higher CR in patients without cognitive impairment suggests that CR acts as a buffer against the development of cognitive deficits in depression.