There are several potential explanations for the lack of association of psychiatric disorders with most of the cocaine dependence severity indices examined here. First, the most obvious explanation is that there is no relationship—or at most a circumscribed relationship— between psychiatric disorders and the severity of cocaine dependence. Prior studies have shown a mixed pattern of results, often finding that psychiatric disorders are associated with severity of or impairment due to SUDs on some indices (e.g., employment problems, suicide risk) but not on others (e.g., response to treatment) (Ladd & Petry, 2003; Mills et al., 2007; Trafton et al., 2006; Wild et al., 2005). SUD severity in particular has been quite variably related to psychiatric comorbidity, and thus the present findings tend to support the view that psychiatric comorbidity should not be assumed to lead to more severe cocaine dependence.
