Comparison of the course of substance use disorders among individuals with and without generalized anxiety disorder in a nationally representative sample.

Generalized anxiety disorder (GAD) and substance use disorders (SUDs) are highly comorbid, and GAD-SUD comorbidity is associated with a host of poor psychosocial outcomes, including higher rates of hospitalization, disability, functional impairment, and inferior GAD and SUD treatment outcomes. Despite the noted severity of this group and clinical implications, current research is limited in a few distinct ways; studies have rarely utilized a longitudinal design and non-treatment seeking individuals to examine how GAD comorbidity impacts SUD outcomes over time. The current study utilized a nationally representative sample of individuals in the U.S. assessed in the National Epidemiological Survey on Alcohol and Related Conditions (NESARC) at Wave 1 (2001-2002) and Wave 2 (2004-2005), comparing individuals who met criteria for both DSM-IV past year GAD and SUD (n = 286) and those who met criteria for past year SUD only without GAD (n = 5730) at Wave 1. Results indicated that GAD-SUD individuals were significantly more severe than the SUD only group across almost all outcomes assessed (with the exception of alcohol frequency); individuals with GAD-SUD had a more severe psychiatric history, worse health-related quality of life at both waves, greater incidence of new Axis I disorders, higher rates of treatment seeking, and greater self-reported drug use at the follow up. The current study is the first to compare individuals with SUD with and without comorbid GAD over time using a nationally representative sample. Findings further support the clinical severity of this group and suggest the need for GAD-SUD treatment options.