There is no single simple cause for alcoholism. Rather, medical experts believe that alcoholism develops from a combination of interrelated genetic and environmental factors. The Department of Psychology at the University of Minnesota reports a three- to four-fold higher risk for alcoholism among first-degree relatives of an alcoholic compared to those without such a family history, demonstrating the strength of the genetic contribution to the disease. Individuals with a family history of alcoholism must exercise caution in their use of alcohol because of their predisposition to addiction.
Various Chromosome Locations
Chromosomes, the packages of genetic information passed down from parent to child, contain thousands of genes. These genes determine all of our characteristics, from our eye color to our hat size. It appears that genes even contribute to determining behavioral traits, such as the tendency to develop addictions. Some of our genes are presumed to contribute to alcoholism.
For years, researchers have sought the specific genes involved in alcoholism to try to better understand the disease. While the specific genes remain largely undefined, certain areas on the chromosomes appear to play an important role in alcoholism. A study published in "American Journal of Psychiatry" that examined the chromosomes of siblings who battled alcoholism with or without depression discovered that a gene or genes on chromosome 1 may predispose some people to alcoholism and possibly depression. Sections of other chromosomes may also harbor genes that play a role in alcoholism. Various genes may also interact together in a combined fashion to set the stage for alcoholism.
Addiction and Neurotransmitter Systems
The tendency to addiction appears to be genetic in and of itself. People with alcoholism have a higher chance to be addicted to other substances and behaviors as well, such as smoking and gambling. In fact, up to half of an individual's risk of becoming addicted to nicotine, alcohol, or other drugs depends on genetic influences, based on results of twin studies, according to the National Institute on Drug Abuse.
Addiction also can be linked to imbalances of neurotransmitters, the chemical signals that pass between neurons in our brain. Neurotransmitter imbalances may also be inherited. We have various types of neurotransmitters; one such neurotransmitter pathway believed to directly relate to addiction and the sensation of pleasure is the mesolimbic dopamine system. According to the book "Genetic Influences on Neural and Behavioral Functions," alcohol-induced changes in neurotransmitter systems likely influence the development of tolerance to alcohol, which is one of the hallmarks of alcoholism.
Inherited Event-Related Brain Potentials
Event-related brain potentials, or ERPs, are recordings of brain activity produced by electrodes placed on the scalp. People with alcoholism and psychiatric disorders tend to have altered ERPs. Furthermore, family members of people with altered ERPs are more likely than the general population to also show altered ERPs, indicating a genetic basis to ERPs.
One particular ERP alteration, which is called a reduction of amplitude of the P3 component, occurs in people with alcoholism and their offspring. According to a study published in the "American Journal of Human Genetics," a person's P3 amplitude appears to be strongly influenced by genetic factors, particularly sections of DNA located on chromosomes 4 and 5.
References
- University of Minnesota Department of Psychology: Is Alcoholism Genetic?
- National Institute on Drug Abuse: Genetics of Addiction
- "American Journal of Psychiatry"; Evidence for a Locus on Chromosome 1 That Influences Vulnerability to Alcoholism and Affective Disorder; J.I. Nurnberger et al; 2001
- "Genetic Influences on Neural and Behavioral Functions"; Donald Pfaff; 2000
- "American Journal of Human Genetics"; Genetics of Event-Related Brain Potentials in Response to a Semantic Priming Paradigm in Families with a History of Alcoholism; L. Almasy et al; 2001
