Major depression and explicit memory

Abstract

Introduction: Major depression is a highly prevalent affective disorder with great personal and social impact. It can generate remarkable deficits in important psychological functions such as executive function, attention or memory and evolve into a profile of pseudodementia that can be ameliorated with antidepressive treatment.

Objective: To describe explicit memory functioning in major depressive disorder.

Materials and methods: Using the key words "major depression", "explicit memory", and "recollection memory", a search in PUBMED was carried out, selecting articles published after 2000. Additonal relevant scientific bibliography was also included.

Results: In the neuroanatomy of the major depressive disorder fronto-subcortical networks are involved, among them prefrontal areas, the thalamus, basal ganglia, and the hippocampus. Atrophy of these structures may explain the persistence or chronicity of some cognitive symptoms of depression. Alterations of explicit, declarative or recollection memory are particularly important because of their frequency in subjects with one or more depressive episodes. The hippocampus is the cerebral structure more directly related with alterations of the explicit memory. In the hippocampus of adult animals continuous neurogenesis activity has been observed, and it is especially vulnerable to prolonged severe stress. Hippocampal volume has been found to be reduced in individuals with major depressive disorder, as compared to healthy ones. Even in the absence of marked volume reduction, there may be alterations in hippocampal function. Conclusion: Explicit memory is a psychological process with a very clear biological basis whose structure and function may be altered in the presence of major depression.