Molecular biology of addiction and substance dependence
Addictions are chronic, devastating psychiatric disorders that are characterized by a compulsive pattern of drug taking or behavior. The development of addictions relies on life style choices but also on genetic, heritable factors that put some individuals at an increased risk for these disorders. Genetic factors for addictive disorders were established by multiple epidemiological studies, showing heritability between 40 and 60%. In an effort to dissect addictive disorders, genetic research was focused on the direct interaction of a variety of drugs with the respective biological systems. Another focus was the identification of long-lasting changes in the brain reward mechanism, using animal models, and more recently brain imaging studies in humans. In the following, we are briefly summarizing the evidence obtained so far for an inheritable trait in addiction as well as what is currently known about the underlying biology.