We used categorical variables (0=absence; 1=presence) to represent the lifetime prevalence of mood, anxiety, and substance use disorders. The prevalence of substance use disorders was low in our sample, except for cannabis- and alcohol-use disorders. Thus, we only examined them and not other substance use disorders. To create substance use variables, we collapsed lifetime cannabis abuse and dependence into one variable, and collapsed lifetime alcohol abuse and dependence into another variable. Following some other studies, we excluded posttraumatic stress disorder (n=4) and acute stress disorder (n=3), because these diagnoses require an external event to occur. Thus, they are not good markers of an intrinsic dimension of internalizing psychopathology (Krueger, 1999).
