Facial emotion recognition deficits in bipolar disorder: A systematic review and meta-analysis

Background: Bipolar disorder (BD) is associated with impairments in facial emotion recognition (FER), affecting social functioning and quality of life. Understanding FER deficits in BD is crucial for tailoring interventions and improving treatment outcomes. This systematic review and meta-analysis aims to evaluate FER differences among individuals with BD, unaffected first-degree relatives (FDRs), and healthy controls (HCs), exploring predictors related to patient and study characteristics. Methods: We systematically searched PubMed/MEDLINE, Scopus, EMBASE, and PsycINFO databases were searched from inception to March 28, 2024. Random-effects meta-analyses were conducted to explore differences in accuracy and reaction time during FER identification and discrimination tasks. Results: A total of 100 studies were included, comprising 4920 individuals with BD (females=56%, mean age=34.1±9.1), 676 FDRs (females=55%, mean age=36.1±12), and 4909 HCs (females=53.2%, mean age=32.5±9.5). Compared to HCs, adults with BD exhibited significantly lower accuracy (SMD = -0.47; 95% CIs = -0.56, -0.38) and higher reaction time (SMD = 0.57; 95%CIs = 0.33, 0.81) during facial emotion identification tasks. During facial emotion discrimination tasks, adults with BD had significantly lower accuracy than HCs (SMD = -0.59; 95%CIs = -0.78, -0.4), but similar speed. No significant differences were observed between BD and FDRs. Meta-regressions identified several predictors of FER performance, including manic symptom severity, stimulus duration, and presence of practice before task. Conclusions: FER deficits appear to be a core feature of BD and require specialized, systematic assessment. Identifying these deficits may help guide interventions aimed at improving affective cognition and social outcomes in individuals with BD.