Cognitive functioning in euthymic recurrently depressed patients: Relationship with future relapses and prior course of disease

Background: Cognitive impairment seems to persist during the euthymic phase of recurrent depression but its relationship with future relapses as with prior course of the disease has to be elucidated. The purpose of this study is to investigate the presence and prognostic value of cognitive dysfunctions for relapse in high risk euthymic patients and to identify relevant associations between cognitive functioning and prior course of illness.

Methods: Standardized neuropsychological tests of mental speed, memory and executive functioning were assessed in 137 remitted patients and compared with clinically used published normative data. Previous episodes and relapses within 24 months were measured using the Structured Clinical Interview for DSM-IV.

Results: Cognitive performance was significantly impaired on 12 of the 14 variables indicating deficits in the domain of speed of information processing and memory. With Cox regression no significant neuropsychological predictors for relapse or recurrence were identified. Furthermore, Pearson correlations between neuropsychological test scores and number of previous episodes, residual depressive symptoms and duration of remission were non-significant. Later age of onset was correlated with a slower speed of information processing and lower verbal memory performance.

Limitations: Published test reference data were used but no healthy control group.

Conclusion: Presence of mild cognitive impairment in remitted patients was demonstrated but did not predict future relapses nor was it related with prior course of disease except for age of onset. Though, mild cognitive impairment after remission might have an impact on the quality of life, adding techniques from cognitive rehabilitation might prove to be a treatment option. (C) 2012 Elsevier B.V. All rights reserved.