The studies reviewed indicate that brain stress system play an important role in the acquisition and maintenance of drugs of abuse that target the brain's reward centers. In doing so, they may destabilize these areas, making the perception of pleasure more elusive and difficult to attain. Withdrawal from drugs of abuse leads to the activation of brain CRF systems that may produce the anxiogenic response associated with
drug withdrawal. More research, however, is needed to investigate the role of brain stress systems and
neuropeptides in other
drug withdrawal symptoms such as
anhedonia. A better understanding of the brain systems underlying
drug withdrawal may help in the development of improved
pharmacotherapies that can alleviate
drug withdrawal symptoms. The second part of the article indicated that there is a very high comorbidity between depression and
drug dependence. The reviewed studies suggest that depressed patients initiate
drug-taking behavior to self-medicate the symptoms associated with their
psychiatric disorder. Chronic use of drugs of abuse, however, may exacerbate the symptoms of pre-existing
mental disorders and subsequently increase
drug-taking behavior. Conversely, professional treatment of pre-existing
psychiatric disorders may decrease the use of illicit substances.