Cognitive Dysfunction in Mood Disorder: Similarities and Differences Between Depression Subtypes

Cognitive dysfunction is common in depression. Depression is hetero-geneous conditions that comprise biologically diverse subtypes. This manuscript reviewed the similarities and differences in cognitive function between major depressive disorder (MDD) and bipolar disorder (BD). Relatively few studies have compared the cognitive function in BD and MDD; furthermore, the differences might ex-ist between BD types I and II. The neu-robiological background of cognitive impairment in MDD and BD involves structural and functional disturbances in neural circuits, as well as disturbances in the connectivity of cognitive networks. Several clinical factors such as symptom severity, onset age, premorbid IQ, psychotic features, and illness course may influence cognitive dysfunction in depression. To under-stand the differences between the cognitive dysfunctions of MDD and BD, the aforementioned features should be controlled. Setting a standard of evaluating cognitive functions in various mood disorders will be a critical step for future studies.