To the Editor: I greatly appreciate the letter of Dr. Goodman because it gives me a chance to expound on the nature of addiction. This is really one of the most complex biopsychosocial problems faced by clinicians. One of the difficulties in conceptualizing this problem is that observers have a tendency to view it from one dimension at a time; addiction requires consideration of multiple, simultaneous, and continuous variables. Dr. Goodman is right on target in pointing out that addiction is much more than just tolerance and withdrawal, although tolerance and withdrawal may be extremely important in any given case.

My own view is more completely expounded in a chapter in the work by Goodman and Gilman R7015511CHDBBDFD. Table 24–1, using the model of an infectious disease, lists categories of variables that interact to determine both initiation and continuation of drug use. Among the agent (drug) variables are availability, cost, and purity. Among the host variables are some of those listed by Dr. Goodman as "genetically based variations." Some of these genetically based variations tend to protect the individual against becoming addicted. For example, the flushing reaction to alcohol would tend to reduce the probability of becoming an alcoholic, yet people with the flushing reaction still can overcome it and become alcohol dependent. On the other hand, the tendency to develop rapid tolerance makes an individual more likely to become an alcoholic R7015511CHDCJIAH, but many people who inherit this tolerance totally avoid alcohol because they have seen the devastation that it wreaks among family members. The third category of variables is environmental. Social pressures and approval or disapproval of peers are influential. The current wave of binge drinking in colleges may influence the probability of developing alcoholism among students, but it will not be the sole determinant.

Thus, any simple statement about addiction is likely to be incomplete or even wrong. This is what makes addiction such a fascinating subject to study and a challenging problem to treat.