In the following discussion on neurotoxins, the reader will appreciate a number of phenomena: tolerance (lessening effect of increasing dose), dependence and addiction (insatiable need), habituation, drug-seeking behaviors, and abstinence with its associated withdrawal effects. Particularly difficult in reference to drugs such as nicotine is the separation of habituation from addiction, that is, of psychologic dependence from physical dependence (see further on).
The few examples given earlier are intended to provide a glimpse of the complex interactions between chemical agents and the cells of the nervous system. For more specific information, the reader is referred to The Biochemical Basis of Neuropharmacology by Cooper, Bloom, and Roth, a text that we have consulted through its many editions and to Goodman and Gilman’s The Pharmacological Basis of Therapeutics.
Intemperance in the use of alcohol creates many problems in modern society, the importance of which can be judged by the emphasis it has received in contemporary writings, both literary and scientific. These problems may be divided into three categories: psychological, medical, and sociological. The main psychologic issue regards why a person drinks excessively, often with full knowledge that such action will result in physical injury and even death. The medical problem embraces all aspects of alcoholic addiction and habituation as well as the diseases that result from the abuse of alcohol. The sociologic problem encompasses the effects of sustained drinking on the patient’s work, family, and community. Some idea of the enormity of these problems can be gleaned from figures supplied by the United States Department of Health and Human Services, which indicate that up to 40 percent of medical and surgical patients have alcohol-related problems and that these patients account for 15 percent of all healthcare costs. Several surveys have suggested a rate of alcohol dependence of 3 to 5.5 percent of adults. A minimum of 3 percent of deaths in the United States are attributable to alcohol-related causes. More striking, but not at all surprising, is the fact that alcohol intoxication is involved in approximately 45 percent of fatal motor vehicle accidents and 22 percent of boating accidents. It requires little imagination to conceive the havoc wrought by alcohol in terms of suicide, accidents, crime, mental and physical disease, and disruption of family life. Finally, the problems engendered by excessive drinking cannot easily be separated from one another.
Etiology of Alcoholism
The cause of alcoholism as an addiction remains as obscure as it is for other forms of dependence and addiction, although environmental, cultural, and genetic factors are clearly implicated. No single personality type has been shown to predict reliably who will become addicted to alcohol. Similarly, no particular aspect of alcohol metabolism has been found to account for the development of addiction, with the possible exception of aldehyde dehydrogenase (see further on). Some persons drink excessively and become alcoholic in response to a profoundly disturbing personal or family problem, but most do not. Alcoholism may develop in response to a depressive illness, more so in women than in men, but far more often depression is a consequence of drinking. Social and cultural influences are undoubtedly important in the genesis of alcoholism as evidenced, for example, by the remarkably high incidence of alcoholism and drinking problems in the American Indian and Eskimo populations and by the disparity in the prevalence of alcoholism, within a single community, among various ethnic groups. However, no ethnic or racial group and no social or economic class are exempt.