Characteristics of injection drug users derived from a large family study of alcoholism

Most descriptive studies on injection drug users (IDUs) has used treatment or referral samples. This study uses relatives ascertained through the Collaborative Study on the Genetics of Alcoholism (COGA) to describe patterns of drug use, psychiatric comorbidity, and selected high-risk behaviors among IDUs not ascertained through treatment or other referral networks. Relatives (N = 5,520) of alcoholic probands were administered a semistructured interview, the Semistructured Assessment for the Genetics of Alcoholism (SSAGA), which assesses lifetime psychiatric symptoms and psychoactive substance use. IDUs were compared with those who had never used cannabis more than 20 times or other drugs more than 10 times (minimal drug use group), those who had used cannabis more than 20 times but no other illicit drugs more than 10 times (cannabis users), and those who had used other drugs more than 10 times but who had never injected (other drug users). Compared with other drug users, IDUs reported using more classes of drugs and began drug use at an earlier age. IDUs were significantly more likely to receive diagnoses of antisocial personality disorder (ASPD) and alcohol dependence, and reported elevated rates of suicidal ideas and attempts. IDUs were more likely to report a variety of behavioral difficulties beginning before age 15, and were more likely to engage in high-risk sexual behaviors. Half of the IDUs reported having shared needles; sharers were more likely to receive a diagnosis of ASPD, but did not differ on reporting high-risk behaviors. IDUs, regardless of whether selected through treatment, have high lifetime rates of mood disturbance and ASPD, and are likely to have a history of conduct difficulties beginning before age 15 years and to subsequently engage in a variety of other high-risk behaviors.