Adherence to pharmacotherapy in bipolar disorder patients with and without co-occurring substance use disorders.

Objective: To examine patterns of adherence to mood stabilizers and reasons for nonadherence in patients with bipolar disorder, with and without substance use disorder (SUD).

Method: From December 2003 to October 2004, 115 patients with DSM-IV-diagnosed bipolar disorder (58 with SUD and 57 without SUD) were administered a structured interview regarding their lifetime experience with mood stabilizers.

Results: Lifetime adherence with mood stabilizers for the SUD group was 65.5%, versus 82.5% for the non-SUD group (p < .05). Lifetime lithium adherence for the SUD group was lower than for the non-SUD group (65.9% vs. 85.0%, p < .05). Substance-related reasons were more commonly cited by the SUD group than the non-SUD group. In contrast, pill- and dosage-related reasons were more frequently endorsed by the non-SUD group than the SUD group.

Conclusion: In bipolar disorder patients, those with co-occurring SUD were less adherent than those without SUD. The SUD group was also less adherent to lithium than the non-SUD group. The reasons for nonadherence differed by presence or absence of a SUD. Physicians should be alert to these differences in their clinical practices while prescribing medications.