Scientists interviewed 1,196 male twin pairs about their history of use, abuse, and/or dependence on marijuana, sedatives, stimulants, cocaine, opiates, hallucinogens, inhalants, and over-the-counter medications. Subjects in the study ranged from 20 to 58 years old.
Upon analyzing data from the interviews the scientists could find no evidence that shared genetic or environmental factors increased the risk of abusing one specific illegal drug over another. The decision to use and abuse a specific drug seemed to depend on unshared factors, such as ease of access.
The findings suggest that the search for genetic variations that affect human drug abuse should focus on factors that increase or decrease the risk of abuse of all types of illegal substances, not just a specific drug.
Dr. Kenneth Kendler and colleagues from the Medical College of Virginia, Virginia Commonwealth University in Richmond published this research in the April 2003 issue of the American Journal of Psychiatry.
