An identical twin high-risk study of biobehavioral vulnerability.

The proposed study begins with the assumption that individuals differ in their vulnerability to develop drug abuse. Therefore, a crucial step in developing prevention and treatment programs for drug abuse is the identification of the biobehavioral basis of the vulnerability. The proposed study is a type of high-risk study using only identical (monozygotic, MZ) twins, rather than a conventional twin approach with both MZ and dizygotic (DZ) twins. The examination of MZ twins discordant for abuse offers the unique opportunity to use genetically identical individuals to look for potential biological and psychological markers or correlates of vulnerability unconfounded by the effects of drugs; it is a method for disentangling the cause and effect of drug usage, albeit in a high-stress, atypical group.