TOPLINE:

Poor medication adherence in bipolar disorder (BD) was associated with younger age, lower education levels, earlier age at onset, psychotic features, and more manic and mixed episodes. Cannabis use disorder (CUD) more than doubled the risk for poor adherence, and alcohol use disorder (AUD) and comorbid generalised anxiety disorder (GAD) also increased the risk for non-adherence.

METHODOLOGY:

• Researchers conducted a systematic review and meta-analysis of observational studies examining correlates of poor adherence to psychopharmacologic treatment in BD, searching several databases through March 2025.
• A total of 19 studies published between 1997 and 2023 were included, with sample sizes ranging from 44 to 2205 participants; the majority of studies (n = 17) were conducted in Europe.
• Adherence was assessed using clinical evaluation, measurement of blood concentrations of psychotropic drugs, or both methods to distinguish good and poor adherence according to the set criteria of each study and the respective cutoff.
• Random-effects meta-analyses were performed to obtain pooled odds ratios (ORs) and standardised mean differences (SMDs) for relevant sociodemographic and clinical correlates, with statistical significance set at P < .05.

TAKEAWAY:

• Participants with poor adherence were younger (SMD, -0.22; P = .031), had fewer years of education (SMD, -0.34; P = .002), and were less likely to be in a relationship (OR, 0.54; P = .009).
• Poor adherence was associated with an earlier age at onset (SMD, -0.29; P = .023), psychotic features (OR, 1.58; P < .001), a history of suicide attempts (OR, 1.36; P = .030), and more previous hospitalisations (SMD, 0.53; P < .001).
• CUD (OR, 2.34; P < .001), AUD (OR, 1.71; P < .001), comorbid GAD (OR, 3.70; P < .001), and comorbid personality disorder (OR, 5.54; P = .019) were linked to poor adherence.
• Participants with poor adherence had higher global severity (SMD, 0.21; P = .042) and lower insight (SMD, -0.74; P < .001) and global functioning (SMD, -0.60; P < .001) than those with better adherence.

IN PRACTICE:

"This systematic review and meta-analysis provides a comprehensive overview of the factors associated with poor medication adherence in individuals with BD, highlighting key sociodemographic and clinical characteristics of this population that may guide targeted early interventions in high-risk groups," the authors wrote.

"Future research should also explore the causal pathways linking clinical factors to poor adherence and examine additional determinants to help refine adherence-enhancing strategies in BD," they added.

SOURCE:

The study was led by Francesco Bartoli, University of Milano-Bicocca, Monza, Italy. It was published online on June 10, 2026, in Bipolar Disorders.

LIMITATIONS:

The study was limited by the cross-sectional and observational design of the included studies, high between-study heterogeneity (I² > 80%), small effect sizes, data imprecision, and inconsistency across overall estimates. It was further limited by the potential for publication and selective reporting biases, as well as insufficient data on key variables such as medication side effects, predominant polarity, and affective temperaments.

DISCLOSURES:

Open access publishing was supported by Università degli Studi di Milano-Bicocca. No information on conflicts of interest was reported.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.