Identification of the predominant polarity, i.e. hypomanic/manic (mPP) or depressive predominant polarity (dPP), might help clinicians to improve personalised management of bipolar disorder.

We performed a systematic review and meta-analysis to estimate prevalence and correlates of mPP and dPP in bipolar disorder.

The protocol was registered in the Open Science Framework Registries (https://doi.org/10.17605/OSF.IO/8S2HU). We searched main electronic databases up to December 2023 and performed random-effects meta-analyses of weighted prevalence of mPP and dPP. Odds ratios and weighted mean differences (WMDs) were used for relevant correlates.

We included 28 studies, providing information on rates and/or correlates of mPP and dPP. We estimated similar rates of mPP (weighted prevalence = 30.0%, 95% CI: 23.1 to 37.4%) and dPP (weighted prevalence = 28.5%, 95% CI: 23.7 to 33.7%) in bipolar disorder. Younger age (WMD = −3.19, 95% CI: −5.30 to −1.08 years), male gender (odds ratio = 1.39, 95% CI: 1.10 to 1.76), bipolar-I disorder (odds ratio = 4.82, 95% CI: 2.27 to 10.24), psychotic features (odds ratio = 1.56, 95% CI: 1.01 to 2.41), earlier onset (WMD = −1.57, 95% CI: −2.88 to −0.26 years) and manic onset (odds ratio = 13.54, 95% CI: 5.83 to 31.46) were associated with mPP (P < 0.05). Depressive onset (odds ratio = 12.09, 95% CI: 6.38 to 22.90), number of mood episodes (WMD = 0.99, 95% CI: 0.28 to 1.70 episodes), history of suicide attempts (odds ratio = 2.09, 95% CI: 1.49 to 2.93) and being in a relationship (odds ratio = 1.98, 95% CI: 1.22 to 3.22) were associated with dPP (P < 0.05). No differences were estimated for other variables.

Despite some limitations, our findings support the hypothesis that predominant polarity might be a useful specifier of bipolar disorder. Evidence quality was mixed, considering effects magnitude, consistency, precision and publication bias. Different predominant polarities may identify subgroups of patients with specific clinical characteristics.

Individuals with bipolar disorder often have a ‘predominant polarity’ (e.g. depressive or manic) that characterizes the majority of episodes over the course of the illness. Genome-wide association studies have suggested a relationship between genetic risk and phenotypic heterogeneity in bipolar disorder. However, to date, no study has directly examined the association between polygenic liabilities and predominant polarity in bipolar disorder.

To estimate the associations between the polygenic risk score for major depressive disorder (PRS-MD), bipolar disorder (PRS-BD) and schizophrenia (PRS-SZ), and predominant polarity among individuals with bipolar disorder in hospital-based settings in Denmark.

The study sample will include all individuals from the Initiative for Integrated Psychiatric Research (iPSYCH2015) sample who received a diagnosis of bipolar disorder and were successfully genotyped (approximately 3,400). Information on polarity will be computed based on data from the Danish Central Psychiatric Research Register. PRS variables will be generated using the most recent results from the Psychiatric Genomics Consortium. Odds ratios for the associations between PRS variables and polarity will be estimated using logistic regression.

We hypothesize that PRS-MD will be highest among the predominantly depressed patients, that PRS-BD will be highest among those with predominantly manic/mixed episodes, and that PRS-SZ will be highest among those who experience psychotic mania or psychotic bipolar depression. The results will be shown at the conference.

A finding of association between genetic liability and predominant polarity in bipolar disorder could pave the way for stratification on genetic liability in future treatment studies and in clinical practice.

No significant relationships.