Screening for cognitive dysfunction in unipolar depression: Validation and evaluation of objective and subjective tools

Abstract

Background: Persistent cognitive dysfunction in unipolar depression (UD) contributes to socio-occupational impairment, but there are no feasible methods to screen for and monitor cognitive dysfunction in this patient group. The present study investigated the validity of two new instruments to screen for cognitive dysfunction in UD, and their associations with socio-occupational capacity.

Method: Participants (n=53) with UD in partial or full remission and healthy control persons (n=103) were assessed with two new screening instruments, the Danish translations of the Screen for Cognitive Impairment in Psychiatry (SCIP-D) and Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA) and with established neuropsychological and self-assessment measures. Depression symptoms and socio-occupational function were rated with the Hamilton Depression Rating Scale and Functional Assessment Short Test respectively.

Results: The SCIP-D and COBRA were valid for detection of objective and subjective cognitive impairment, respectively. The three parallel SCIP-D forms were equivalent. A combined SCIP-D-COBRA measure showed high sensitivity and good specificity for objective cognitive impairment (91% and 70%, respectively). There was no correlation between subjective and objective measures of cognition. Subjective cognitive difficulties correlated more with socio-occupational impairment (r=0.7, p<0.01) than did objective cognitive difficulties, for which there was a weak correlation with the executive skills domain only (r =-0.3, p=0.05).

Limitations: A modest sample size.

Conclusions: The SCIP-D and COBRA are valid measures of objective and subjective cognitive impairment, respectively, and should ideally be implemented together in the screening for cognitive dysfunction in UD.

Keywords: Assessment; Cognition; Depression; Mood disorder; Screening; Socio-occupational function.