Co-occurrence of bipolar disorder and personality disorders in the United States: Prevalence, suicidality, and the impact of substance abuse

Abstract

BackgroundThis study investigates prevalence rates of specific personality disorders (PDs) in individuals with bipolar disorder (BD) and their impact on substance abuse and suicidality, addressing existing gaps in the literature. MethodsUsing Nationwide Inpatient Sample data (2016–2020), adult hospitalizations for BD with coexisting PDs were analyzed. Study variables were defined using ICD-10-CM codes. Prevalence of PD were reported as cases per 100,000 BD admissions. Regression models assessed the association between substance abuse and suicidality. ResultsAbout 993,000 admissions for BD were analyzed. The cohort was predominantly Caucasian (70.5 %) with higher female representation (54.5 %). The mean age was 41 years. 89.4 % of individuals had a Charlson Comorbidity Index score ≤ 1. The most common diagnostic subtype was manic episode of BD with or without psychotic features (32.3 %). Coexisting PDs were observed in 12.2 % of the population, with borderline PD (8.2 %) and antisocial PD (2.6 %) being most prevalent. Substance abuse was common (44.8 %), with cannabis (23.8 %), alcohol (19.4 %), cocaine (10.5 %), and opioids (9.6 %) being most reported. Substance abuse was higher in individuals with BD and PD (50 %) compared to BD alone (44.1 %). 596 suicide attempts were recorded (60 per 100,000 BD admissions). Substance abuse and coexisting PD in bipolar individuals elevated the likelihood of attempts (P < 0.001). LimitationsUse of administrative data (retrospective, inpatient); treatment not studied. ConclusionThe study reveals a notable prevalence of PDs in individuals with BD, with increased likelihood of substance abuse and suicide attempts in those with coexisting BD and PD compared to BD alone.