Meta-analysis of depression and substance use and impairment among cocaine users (2008)

BACKGROUND: The study evaluated, among cocaine users, the hypothesized positive association of depression and concurrent cocaine use and impairment, alcohol use and impairment, and general drug use and impairment. The hypothesis that gender would moderate these associations, with women showing a stronger correlation between depression and measures of substance use and impairment, was also tested. Also examined was the association of depression with future cocaine use and impairment and substance use treatment participation.
METHODS: Empirical reports on adult cocaine users published in English in peer-reviewed journals since 1986 that contained data on depression and substance use outcome(s) were obtained using a systematic search. Studies that placed restrictions on range of depression scores to select the sample, experiments that administered cocaine to subjects, and trials of antidepressant medications were excluded. The search yielded 60 studies for the analysis including 53 reports that collected data from clinical venues and seven that were community-based.
RESULTS: As hypothesized, the analyses showed that depression is associated with concurrent cocaine-, alcohol-, and general drug use and impairment. Effect sizes were small. Hypothesized moderating effects of gender were not supported. Depression was not associated, at a statistically significant level, with treatment participation or future cocaine use and impairment.
CONCLUSIONS: Depression is consistently but modestly associated with measures of cocaine-, alcohol-, and general drug use and impairment among cocaine users. Associations of depression with treatment participation and with future cocaine use and impairment are not immediately evident, although limitations of data warrant cautious interpretation.