Monday, October 8, 2012

The Genetics of Addiction


When scientists are looking for "addiction genes," they are looking for the biological and environmental differences that make a person more or less susceptible to addiction.  It might be harder for certain people with certain genes to quit something once they have already started. The question is why are some people so easily addicted to drugs and/or alcohol, while other people can party and never do it again?  Some people may experience more severe withdrawal symptoms if they try to quit a drug, then others, and some have no withdrawal systems at all. We sometimes think it's a simple matter of willpower or your train of thought, but the fact is, it has more to do with the roll of the genetics. Also the factors that make it harder to become addicted also may be genetic.
            Scientists and researchers will never find just one single addiction gene.  Addiction has been proven as the result of many interacting genes.  Of course, personal experience, including childhood experiences, environmental and social influences matter in the role of addiction. Researchers have been constructing pedigrees of large families with addiction problems as a first step to understanding the roles and factors of addiction.  A pedigree can reveal whether or not a certain trait has a genetic component.  That means, whether or not the trait is passed down from parent to child by way of genes. But because addiction is influenced by multiple genes as well as many other risk factors, this can be a complicated process. Using this pedigree data, researchers and scientists can begin to track down genes. Researchers begin by comparing certain DNA sequences of individuals who are addicted with those individuals who are not. They can then narrow down the possibilities to identify a small number of so-called "candidate genes" for addiction. But not every addict will carry the same gene, and not every person who carries an addiction gene will exhibit the same trait or get addicted to the same thing, or even get addicted to anything at all. For example, the A1 allele of the dopamine receptor DRD2 gene is much more common in people addicted to alcohol.  Most of these genes wouldn't even have been discovered without the use of animal studies, mice preferably. These studies on done on mice shows that the increased expression of the Mpdz gene experience less withdrawal symptoms from barbiturates then mice without this gene. Also, certain studies show that people that are non-smokers are more likely to carry a protective gene, CYP2A6, which causes them to feel more nausea and dizziness from smoking cigarettes. In alcoholism, it is rare for people with two copies of the ALDH*2 gene to even become alcoholics, and people without this gene seem to be more susceptible to this disease. In both animals and humans, individuals who are less sensitive to these unpleasant effects have a higher rate of addiction. Regions on chromosomes 4 and 5 that govern the neurotransmitter GABA appear to play a key role in determining alcohol tolerance (http://money.cnn.com/2009/10/16/news/genes_addiction.fortune/index.htm).
This study has taught me that addiction happens because of many factors, whether its genetics, environmental or situational. The fact or the matter is that addiction is a disease.  Your surroundings, genetics and experiences and maybe just a little will power, affect your susceptibility to become addicted.

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