Clinical features, response to treatment and functional outcome of bipolar disorder patients with and without co-occurring substance use disorder: 1-year follow-up.

INTRODUCTION: Bipolar disorder patients (BP) with comorbid Substance Use Disorder (SUD) may present clinical features that could compromise adherence and response to pharmacological treatment. The purpose of this study was to examine clinical and psychopathological features of BP with and without comorbid SUD in a real-world setting.
METHODS: The sample was composed by 131 affective patients. Sixty-five patients were affected by Bipolar Disorder I (BP-I, 49.2%), 29 by Bipolar Disorder II (BP-II, 22.3%) and 37 by Cyclothymic Disorder (CtD, 28.5%), according to DSM-IV. Sixty-six patients were diagnosed for a comorbid SUD. All patients have been submitted to psychometric assessment with Hamilton Depression Rating Scale (HDRS), Hamilton Anxiety Rating Scale (HARS), Young Mania Rating Scale (YMRS), Global Assessment Scale (GAS), Social Adjustment Self-reported Scale (SASS), Quality of Life Scale (QoL), at baseline and repeated follow-up periods (1, 3, 6, 12 months).
RESULTS: BP comorbid for SUD were more likely diagnosed as BP-II and CtD and were less likely to present a moderate-severe manic symptomatology. Furthermore, personality disorders were more frequent in SUD patients than in non-comorbid BP. BP with SUD were not different for primary outcome measure (HDRS, HARS, YMRS, GAS) from non-comorbid BP; however, BP with SUD were significantly more impaired in social functioning (SASS) at any stage of the follow-up and poor functioning increased the risk of relapse in substance use during treatment. Finally, SUD comorbidity did not represent a risk factor for treatment drop-out, while in our sample young age, low treatment dosage and BP-I diagnosis were significantly associated with drop-out. DISCUSSION: The primary finding of this work is that BP with comorbid SUD are significantly more compromised in social functioning. Second, these patients were less likely to be diagnosed for BP-I and to present a severe manic symptomatology. Finally, we found that the diagnosis of SUD, but young age, low treatment dosage and BP-I diagnosis to be risk factors for treatment drop-out. Physicians should be alert to these differences in their clinical practice.