Learning and memory differences among women with and without Major Depressive Disorder (MDD)

This study examines whether females with MDD demonstrate poorer list learning and recall than healthy controls (HC), and related activation abnormalities.
Female participants (HC= 16, MDD= 17) completed the Semantic List Learning Task (SLLT) during fMRI; after the scan, they were asked to recall material presented during the task. Analyses included between-group comparisons of encoding versus distraction blocks, and event-related analyses of encoded words that were subsequently recalled.

Although there were no significant differences in the overall recall between MDD and HC groups, there were significant differences in neural activation for the Encoding minus Distraction contrast such that the HC group exhibited greater activation in: right precuneus, middle and superior frontal gyri, and cerebellum; left superior temporal and postcentral gyri; and bilateral insula, inferior frontal gyrus, and dorsal anterior cingulate. For the same contrast, MDD exhibited greater left medial temporal and bilateral cuneus activation. In the event-related analyses, HC exhibited greater activation in the right posterior parahippocampal gyrus whereas MDD exhibited greater activation in the right caudate, right dorsal cingulate and left inferior frontal gyrus.
Behavioral recall did not differ between groups, perhaps due to low statistical power, whereas fMRI data indicated that patients with MDD may not engage neurocircuitry underlying memory to the degree of healthy individuals. These findings may help explain memory complaints in MDD and future studies could examine larger samples, and take into account frequency, salience and valence of the stimuli.

No relevant conflicts of interest declared.