The inclination to dilute boredom chemically for a while is part of the reason sociopaths tend to be alcohol and drug abusers. A major comorbidity study published in 1990 in the Journal of the American Medical Association estimates that as many as 75 percent of sociopaths are dependent on alcohol, and 50 percent abuse other drugs. And so sociopaths are often addicts in the usual sense, in addition to being figuratively addicted to risk. With its "peak experiences" and its dangers, the drug culture holds more than one form of appeal for the conscienceless, and the drug culture is where many sociopaths feel most at home.
Another study, published in 1993 in the American Journal of Psychiatry, found that 18 percent of intravenous-dug abusers diagnosed with antisocial personality disorder were HIV-positive, while only 8 percent of intravenous-drug abusers without antisocial personality disorder tested positive for HIV. The higher odds ratio of HIV infection among sociopaths is presumably due to their greater risk-taking behaviors.
--Martha South, Ph.D. in The Sociopath Next Door, p187.