Determinants of Addiction. Biological Determinants. Psychological Determinants

As indicated earlier, addiction has no simple explanation. It is a complex “biopsychosocial” phenomenon, with multiple determinants. In this section, we review the major categories of explanations that have been offered to account for addiction, and we consider how these various explanations can be made congruous.

Biological Determinants. People’s reactions to psychoactive drugs vary widely, and some of this variability can be explained biologically. For example, different people metabolize alcohol and its metabolic byproducts in very different ways, due in part to genetically determined differences in their levels of liver enzymes for metabolizing alcohol and its metabolites.

Acetaldehyde, one of alcohol’s metabolites, is a poisonous substance that can cause symptoms such as an upset stomach and flushing of the skin. People who have insufficient amounts of the liver enzyme aldehyde dehydrogenase, which is necessary for acetaldehyde to be metabolized, experience stronger negative effects from drinking than do other people. As a consequence of their biological “protection,” these individuals are less likely to drink large quantities of alcohol—and, hence, are less likely to become addicted to alcohol—than are people with an adequate level of aldehyde dehydrogenase.

Research on opioids further clarifies the role of biological factors in addiction. This research has identified specific receptors in the brain where opiates first begin to affect the central nervous system. Additionally, a group of opioidlike substances known as endorphins have been identified as chemicals that the body produces endogenously. These naturally produced substances are thought to play a critical role in the regulation of people’s moods and psychological well-being and in their reactions to noxious, pain-inducing stimuli.

What role do endorphins play in addictions? At this time, the evidence is by no means conclusive, but one possibility is that people who are addicted to opiates have imbalances in the levels of endorphins in their bodies, and they use opiates to bring about changes in their moods that the naturally occurring substances ordinarily would produce.

Similarly, the positive mood changes that people derive from drinking alcohol appear to be caused by the impact of alcohol on the neurotransmitters, substances in the brain that give rise to pleasurable feelings. Thus, different people probably experience different positive effects from drinking alcohol because of differences in their brain chemistry.

Finally, with regard to alcohol, it should be noted that, although laboratory animals ordinarily refuse to drink alcohol, strains of animals that prefer drinking alcohol to water have been bred. The various lines of evidence that we have cited here leave little doubt that biological factors play a role in addiction.

Psychological Determinants. The first efforts by psychologists to identify the psychological mechanisms involved in addiction were directed at identifying the “addictive personality.” This approach involved administering personality tests to addicts in treatment in an effort to discover how their personality was different from that of other people. The ultimate aim was to identify the personality dynamics of addicts that would account for their addiction.

Certain personality characteristics have, in fact, been frequently observed among people suffering from addictions. For example, they are often antisocial and impulsive, have a low tolerance for frustration, and seem to derive pleasure from activities and experiences that other people would regard as unusual or even dangerous. These personality characteristics, however, certainly do not describe all people who are addicted to psychoactive drugs. Accordingly, the idea that it is possible to identify an addictive personality that will serve as the sole explanation for the addict’s addiction has not been supported.

At the same time, it has been clearly demonstrated that various other psychological mechanisms play an important role in drug addiction. One such mechanism is conditioning. When people habitually use a particular drug, they develop conditioned reactions to the stimulus cues associated with the drug-taking experience. As a result of such conditioning, when people encounter these same stimuli again in the future they are likely to crave the drug, thereby increasing their likelihood of using the drug and maintaining their addiction. Another example of a psychological mechanism involved in addiction is the emotional satisfaction—or lack of it—that people derive from their nondrug life experiences.

When people encounter frustrations in life and do not have adequate psychological resources for coping with them, they are more likely than they would be otherwise to attempt to find emotional solace by using drugs. Similarly, if they do not have positive emotional experiences that preserve their sense of psychological well-being, they are more likely than other people to seek emotional satisfaction through chemical means.