Drug Addiction as a Psychobiological Process

Drug Addiction as a Psychobiological Process

The emphasis is on biological

mechanisms underlying addiction, although some other factors influencing

drug addiction will also be discussed. The presentation is limited primarily to

psychomotor stimulants (e.g., amphetamine, cocaine) and opiates (e.g.,

heroin, morphine) for two reasons. First, considerable knowledge has been

gained during the past 15 years regarding the neurobiological mechanisms

mediating their addictive properties. Second, these two pharmacological

classes represent the best examples of potent addictive drugs, and the

elucidation of their addiction potential can provide a framework for

understanding abuse and addiction to other psychotropic agents. Some

psychologists and sociologists assert that animal studies do not model the

important psychological variables governing drug addiction. They suggest that

psychological processes critical in the etiology of addiction cannot be studied

in animal models and/or that environmental influences important in producing

an addiction cannot be duplicated in animal studies. This position is generally

untenable, and animal models have been developed that accurately represent

the primary processes involved in drug addiction. Support for the validity of

these animal models will emanate from an understanding of the characteristics

and the neural basis of drug addiction summarize...

... middle of paper ...

...endence (i.e., the periaqueductal gray

region; see Figure 2) are not rewarding (Bozarth and Wise 1984). This

neuroanatomical dissociation of reward and physical dependence shows that

opiates can be rewarding without the development of physical dependence.

The interpretation of research identifying the neural basis of opiate reward has

been somewhat controversial, but considerable data suggest that opiates can

activate the same brain reward system as that mediating reward from

psychomotor stimulants. Direct support for this hypothesis comes from a

study showing that ventral tegmental morphine injections can partially

substitute for intravenous cocaine injections (Bozarth and Wise 1986).