Cognitive functioning in major depression--a summary

Abstract

The aim of the present paper is to summarize the research during the past decade regarding cognitive functioning in Major Depressive Disorder (MDD). Cognitive impairment in the acute phase of illness has been frequently reported. The findings are shown in different cognitive domains, such as executive functions, attention, memory and psychomotor speed. Fewer reports have investigated cognitive functioning in MDD in longitudinal studies. Some longitudinal reports show that the impairment observed in the acute phase of illness may be long lasting despite symptom reduction and recovery. However, findings regarding cognitive functioning in depression are divergent. Factors that might contribute to the divergent findings, such as depression subtype, severity and comorbidity are discussed. Clinical implications and focus of future research directions is highlighted.In conclusion, depression is associated with cognitive impairment in the acute phase of illness, and some reports indicate that this impairment might be long lasting despite symptom reduction and recovery.

Keywords: acute phase; cognitive functioning; impairment; long-lasting; major depression.

Figure 1

Illustrates how the profile of cognitive impairment, the risk of relapses and symptom improvement might relate. Several aspects of the course of cognitive impairment remain to be clarified. First, does the cognitive impairment occur before the mood symptoms? See “I” in Figure 1. Secondly, is the time course of cognitive normalization delayed in relation to remission? See “II” in Figure 1. Thirdly, is long lasting cognitive impairment a predictor for enhanced relapse risk or for new episodes? See “III” in Figure 1. Another aspect is to clarify if various cognitive profiles are related to various subgroups of patients. Although several questions remain to be answered, the literature clearly indicates that depressed patients as a group is subject to neuropsychological impairment that may persist despite symptom reduction and remission, see “II” in Figure 1. Following this, another important question rises: How does long-lasting impairment in cognitive functioning affect daily life functioning in depressed individuals?