Seeking the Connections: Alcoholism and Our Genes

Summary

Scientists believe that the tendency to be dependent on alcohol is partially hereditary, since investigators have the power to examine the genes of large populations. There are about a dozen genes that have been identified to make a person susceptable to alcohol, but scientists believe there are more. Variations of these genes only mildly affect vulnerability to alcohol, but may have stronger impacts on drinking habits, depression, or anxiety. Scientists wish to discover the biological processes that are linked to alcohol dependency, so they can come up with better treatments to help alcoholics.



One gene that might have an impact on how much people drink is called ALDH1, (aldehyde dehydrogenase). The enzyme that comes from this gene is supposed to breakdown alcohol, but some people have varitaions of this enzyme that makes it work at a slower rate. When people have large amounts of the variation of this enzyme, they tend to feel uncomfortable because the enzyme is building up in their bodies. Many Asians experience this kind of discomfort when they drink, so they are not as susceptable to alcohol unlike the Europeans who are.



Multiple genes are included in alcoholism and people show problems with it in multiple ways. Reseachers have to be careful in identifying the problem. Some people really are dependent and others just suffer from alcohol abuse. In order to be diagnosed with a dependency to alcohol, or any other substance, one must experience three or more of the following symptoms:

• " tolerance for large doses,
• withdrawl reactions,
• loss of control over use of the substance,
• efforts to stop or cut down,
• a large amount of time invested in the activity,
• giving up other activities and,
• continued use despite resulting physical or psycological problems." (page 48 in magazine)
  
• Apparently, most of the people who are diagnosed with alcohol dependency have relatives with cases of alcohol.
  

A significant method in searching for genes linked to alcohol dependency has been an investigation of endophenotypes. Endophenotypes are measurable and not visible, but they can be examined to see if there are certain patterns that appear more in people with a disorder. The assumption is that endophenotypes can uncover the genetic links for a disorder than behavioral symptoms, because they show a crucial physical trait that is closer to the gene varient.

One form of an endophenotype is the brains activity patterns. The wave forms and spikes in neural activity in the brain vary among individuals. They also show the balance between excitatory processes in the brain, and the inhibitory processes.

These electrophysiological patterns vary between alcoholics and nonalcoholics. The excitation process overpowers the inhibitory one in alcoholics. This trait can also be seen in the children of alcoholics. It would appear that carriers with this pattern are predisposed to alcoholism. These patterns also inhibit a person's judgement.

50% of all risks for alcoholism comes from hereditary factors. Some risk factors include:

• "low response


• previous experience with severe depression and


• specific drinking history patterns." (50)

There are also certain chromosomes linked to alcoholism. Chromosomes 1, 2, 4, and 7 are the most significant ones. Two of the major genes of these chromosomes are GABRA2, and CHRM2.



"GABA is the most common inhibitory neurotransmitter in the mammalian nervous system. It modulates the activity of neurons by binding to GABA- specific receptors in their cell membranes literally inhibiting their responsiveness to signaling." (51) Several groups have found that a variation of GABA (GABRA2) is connected to alcoholism because it is a feature in alcoholic cases.



CHRM2 is a neurotransmitter that effects decision making. This protein changes the manufacture of the receptor protein instead of the structure unlike GABA. It is connected to alcohol dependence and severe depression. The most recently discovered links are providing new ideas for medications for alcoholism and depression.


Another genetic factor for alcohol dependence is a gene that controls taste perception. Some people have a decreased sensitivity for alcohol than others, putting them at a high risk for drinking. This effects many African American as opposed to European Americans.

The piont, is that genes play a big part in alcoholics chioces, and the different genes make people susceptable for different reasons. Some encourage early drinking, some encourage dependence, and others come about through depression to nurture drinking.

However, genes are not everything. People don't become dependent on alcohol without making bad choices, but some people are more vulnerable to drinking than others in certasin situations. Scientists believe that the demand for genetic testing for alcoholism will increase in upcoming years, and they also believe that if people are aware of their susceptability, they might make better chioces.

My Reaction

I thought this article was interesting and insightful because I always just assumed that people became alcoholics due to poor decisions. I never took into account that some people might be more vulnerable to it if they are depressed, or like the taste of it. I agree with the fact that genetics aren't the sole reason that people become alcoholics. And if people have relatives who are alcoholics, then they probably should not drink at all or rarely, since they could have a weakness for it as well.

The only thing I'm not sure on where this article stands is that people play a huge part in their drinking habits. This article says that alcoholism is 50% genetics. That means that people only 50% responsible for their addiction. I believe that genetics only increase risks to become an alcoholic, not that they make people become one. The article did admit that choices were involved, but I believe people have more than a 50% chance not to become alcoholics. This day and age, people are trying to shake the resonsibility for their wrong choices. I feel that this article, while insightful and interesting, is fuel for alcoholics not to blame themselves for their decisions.

http://www.sciam.com/article.cfm?id=seeking-the-connections-alcoholism-and-our-genes