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Cognitive deficits persist into remission of major depressive episodes

Depression-related cognitive deficits in selective attention, working memory and long-term memory persisted into remission from a major depressive episode and worsened with repeated episodes, study findings published in Lancet Psychiatry revealed.

“Clinical targeting of cognitive dysfunction can improve overall outcomes in patients recovering from depression,” Maria Semkovska, PhD, from the department of psychology at University of Limerick’s Health Research Institute, Ireland, and colleagues wrote. “Clarifying the specific pattern of impaired versus preserved cognitive functions after mood stabilization is needed to optimize treatment, targeted preventative approaches and prognosis.”

In a systematic review and meta-analysis, researchers compared the difference in cognitive performance between major depressive episode remitters following a major depressive episode and healthy controls to determine the pattern and severity of persistent cognitive dysfunctions. They also examined the potential moderator effect of prespecified clinical and demographic variables.

Semkovska and colleagues searched clinical databases for studies of patients who were evaluated while in remission from a major depressive episode with at least one cognitive test and a healthy control group evaluated with either the same test as the major depressive episode group or with a standardized test.

Meta-analysis included 75 cognitive variables from 252 studies encompassing 11,882 major depressive episode remitters and 8,533 healthy controls.

The investigators observed significant deficits following major depressive episode remission in 55 (73%) of the 75 cognitive variables in the domains of processing speed, visual selective attention, working memory, verbal learning and executive functioning.

Although the deficits in 52 of the 75 variables were small or moderate in size, analysis indicated large deficits in three long-term memory variables: logical memory immediate recall (g = –0.81; 95% CI, –1.01 to –0.61); logical memory delayed recall (g = –0.88; 95% CI, –1.19 to –0.57) and Cambridge Neuropsychological Test Automated Battery pattern recognition latency (g = –0.84; 95% CI, –1.18 to –0.5). The results also showed that depressive episode remitters were better at identifying emotional expression than controls.

In addition, Semkovska and colleagues reported that the higher the number of previous depressive episodes, the larger the cognitive deficits compared to healthy controls. In most of the variables, the number of previous depressive episodes explained heterogeneity (z = –2·06 [P = .039] to z = –4·26 [P < .0001]).

“Clinical guidelines, current network theories of mental disorders, and relapse prevention interventions for depression need to account for the persistence of cognitive deficits into remission,” the researchers concluded. – by Savannah Demko

Disclosure: Semkovska and another author reports funding from the Irish Research Council. No other authors report relevant financial disclosures.