Associations between cognition and subsequent mood episodes in patients with bipolar disorder and their unaffected relatives: A systematic review

BACKGROUND: Bipolar disorder (BD) is highly recurrent and prevention of relapse and illness onset is an urgent treatment priority. This systematic review examined whether cognitive assessments can aid prediction of recurrence in patients with BD and/or illness onset in individuals at familial risk.

METHODS: The review included longitudinal studies of patients with BD or individuals at familial risk of mood disorder that examined the association between cognitive functions and subsequent relapse or illness onset, respectively. We followed the procedures of the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) 2020 statement. Searches were conducted on PubMed/MEDLINE, EMBASE and PsychInfo databases from inception up until May 10th 2021.

RESULTS: We identified 19 eligible studies; 12 studies investigated cognitive predictors of recurrence in BD (N = 36-76) and seven investigated cognitive predictors of illness onset in at-risk individuals (N = 84-234). In BD, general cognitive impairment, poorer verbal memory and executive function and positive bias were associated with subsequent (hypo)manic relapse -but with not depressive relapse or mood episodes in general. In first-degree relatives, impairments in attention, verbal memory and executive functions and positive bias were associated with subsequent illness onset.

LIMITATIONS: The findings should be considered preliminary given the small-to-moderate sample sizes and scarcity of studies.

CONCLUSIONS: Subject to replication, the associations between cognitive impairment and (hypo)mania relapse and illness onset may provide a platform for personalised treatment and prophylactic strategies.