Behavioral mechanisms underlying the link between smoking and drinking

Many people use both alcohol and nicotine (i.e., cigarettes and other tobac co products). The behavioral effects of these two drugs differ, and they do not act on the same target sites in the brain, although they may share, or partly share, certain properties. The initiation of alcohol or nicotine us e may be precipitated by similar personality characteristics in the user, s uch as impulsivity and sensation seeking. Moreover, the mechanisms underlyi ng the development of dependence may be similar for alcohol and nicotine. T hus, certain factors, such as reinforcing drug effects, conditioning proces ses, automatic behavior, and stress, may influence the development of depen dence on both drugs. Other factors, such as tolerance and sensitization to the drugs' actions and the development of withdrawal symptoms, may also con tribute to dependence. This review discusses the actions of the two drugs o n certain brain chemical (i.e., neurotransmitter) systems and the extent to which the effects of the two drugs may interact.