In this sample of cocaine dependent adults who were recruited as sibling pairs for a genetics study, contrary to Hypothesis 1, psychiatric comorbidity was associated increased severity of cocaine dependence on only one of six cocaine dependence severity indices: “Days of Use in the Heaviest Period of Use.” However, consistent with Hypothesis 2, several psychiatric disorders were associated with an increased likelihood of participation in cocaine dependence treatment or self-help programs. These findings were obtained after controlling for any non-independence of data from the proband and sibling sub-samples, and for demographics and history of other substance dependence diagnoses. SUD comorbidity was the most consistent correlate of cocaine dependence severity, though the direction of the relationship varied depending on the specific SUD and index of cocaine dependence severity. African-American, male, less educated, unemployed, or unmarried participants tended to report higher degrees of cocaine dependence severity, but these demographic factors were unrelated to use of treatment or self-help programs for cocaine dependence, except that African-Americans were more likely than others to report having attended self-help programs.
