Impulsivity in bipolar disorder as influenced by mood state and alcohol/substance use disorder comorbidities: a systematic review and meta-analysis

Background

Bipolar disorder (BD) is a chronic and disabling psychiatric condition characterized by recurrent episodes of mania or hypomania and depression, affecting approximately 1–3% of the population. Impulsivity is a core clinical feature of mania and has been associated with adverse outcomes, including suicidality, poor treatment adherence, and substance misuse.However, it remains unclear whether impulsivity represents a stable trait of BD or varies according to mood state [1,2]. Furthermore, BD frequently co-occurs with alcohol and substance use disorders, both of which are independently linked to increased impulsivity [3]. This study aimed to systematically evaluate impulsivity in BD using the Barratt Impulsiveness Scale-11 (BIS-11), with a focus on total and subdomain scores, mood state (mania, depression, euthymia), and the impact of psychiatric comorbidities.

Methods

A systematic literature search was conducted in PubMed, EMBASE, Cochrane Library, MEDLINE, Scopus, and Google Scholar in accordance with PRISMA guidelines. Studies comparing BIS-11 scores between individuals with BD and healthy controls (HC) were included. Means and standard deviations were extracted for total BIS-11 scores and its subdomains (attentional, motor, and non-planning impulsivity). Random-effects meta-analyses were performed to calculate standardized mean differences (SMDs) and 95% confidence intervals (CIs). Subgroup analyses were conducted according to mood state and the presence of alcohol or substance use disorders. Meta-regression analyses were used to explore associations between impulsivity and clinical variables. All analyses were performed using Comprehensive Meta-Analysis software (version 4.0). A total of 48 studies were included, comprising 6,667 participants (BD = 3,516; HC = 3,151).

Results

Individuals with BD exhibited significantly higher total BIS-11 scores compared to HC (SMD = 1.28, 95% CI: 1.10–1.45; p < 0.0001), indicating a large effect size. Similar elevations were observed across all BIS-11 subdomains, including attentional, motor, and non-planning impulsivity. Subgroup analyses demonstrated that impulsivity remained significantly elevated during euthymia, supporting a trait-like component. In contrast, during manic states, increased impulsivity was observed primarily in attentional and non-planning domains. Insufficient data were available to conduct a meta-analysis for depressive episodes. The presence of comorbid alcohol or substance use disorders was associated with larger effect sizes, indicating an additive or synergistic effect on impulsivity. Meta-regression analyses revealed a marginal positive association between impulsivity and manic symptom severity. Significant heterogeneity was observed across studies, although this was partially reduced in subgroup analyses stratified by mood state and comorbidity. Visual inspection of funnel plots and Egger’s regression test did not indicate significant publication bias.

Conclusions

This meta-analysis demonstrates that impulsivity, as measured by the BIS-11, is significantly elevated in BD across total and subdomain scores, including during euthymic states, supporting its role as a trait characteristic of the disorder. However, the limited number of studies examining patients during manic - and particularly depressive - episodes restricts conclusions about whether impulsivity remains stable across mood states. Comorbid alcohol and substance use disorders further amplify impulsivity in BD. Future research should clarify the relationship between affective states and impulsivity in BD.

References

1-Newman, A.L., Meyer, T.D., 2014. Impulsivity during euthymia in bipolar disorder. Int. J. Bipolar Disord. 2, 2. 2-Santana, R.P., Kerr-Gaffney, J., Ancane, A., Young, A.H., 2022. Impulsivity in bipolar disorder: state or trait? Brain Sci. 12 (10), 1351. 3-Preuss, U.W., Schaefer, M., Born, C., Grunze, H., 2021. Bipolar disorder and illicit substance use. Medicina 57 (11), 1256.