Demographic information for both groups is presented in Table 1. By design, all cases were cocaine dependent. Because substance dependence was not an exclusionary criterion for recruitment of community-based participants, 30.1% of community-based participants were dependent on at least one illicit drug and 19% of the community-based sample was cocaine dependent. Cocaine dependent cases recruited from treatment were significantly more likely to be dependent across all the queried substances (e.g., tobacco, alcohol, cocaine, marijuana, etc.) compared to community-based participants. For additional detail about the rates of drug use and dependence in this sample see Bierut et al. (2008). In addition, cocaine dependent cases recruited from treatment centers were significantly more likely to have lower income, be unemployed, have less education, and be currently unmarried compared to the community-based comparison participants.
