The relative roles of bipolar disorder and psychomotor agitation in substance dependence

Abstract

Previous studies have shown that both bipolar disorder (BPD) and psychomotor agitation (PMA) are associated with substance dependence. These two findings have yet to be integrated, despite evidence that PMA is closely linked with the bipolar spectrum. Accordingly, the current study examined whether BPD and PMA had unique or overlapping associations with substance dependence disorders. Participants were 2,300 individuals seeking outpatient psychiatric treatment. Before treatment, participants were assessed using structured clinical interviews, which yielded DSM-IV psychiatric diagnoses and clinical ratings of mood symptoms. Current PMA and lifetime BPD were present in 483 and 172 (bipolar I, n = 71; bipolar II, n = 101) participants, respectively. Current PMA and lifetime BPD each were associated with increased prevalence of lifetime nicotine, alcohol, and drug dependence (ORs >or= 1.52, ps <or= .0004). These associations remained significant when controlling for demographic characteristics and comorbid psychiatric disorders, except the link between agitation and alcohol dependence, which was reduced to a trend (p = .058). Although BPD and PMA were associated with each other, these two factors demonstrated unique, nonoverlapping relationships to nicotine, alcohol, and drug dependence. Individuals with both PMA and BPD exhibited especially high rates of comorbid substance dependence. The present results replicate and extend previous findings documenting the relations of BPD and PMA to substance dependence. BPD and PMA may represent independent psychopathological correlates of substance dependence. Future research should explore the theoretical and clinical significance of these potentially distinct relations to substance dependence.

Figure 1

Prevalence of Lifetime Nicotine, Alcohol, and Drug dependence across Patients with Neither, One, or Both Psychomotor Agitation and Lifetime Bipolar Disorder ^aRates based on subset of participants who underwent nicotine dependence evaluations (n = 1800)