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Variation in serotonin gene linked to alcoholism

Posted on 09-16-16 in Addiction, Research, Substance Abuse

Variation in serotonin gene linked to alcoholism

Numerous genetic markers for alcoholism have been discovered, but not everyone who has the genetic marker develops the disease. Environmental factors also play a role in the development of the alcoholism. Epigenetic factors are things that modify genes, like switches that can turn them on or off.

Many of the genes associated with the development of alcoholism encode components of neurotransmitters, particularly serotonin. Serotonin is an important neurotransmitter that regulates mood and low levels are thought to cause depression.

A recent review examined the SLC6A4 gene, which encodes a serotonin transporter protein. The researchers looked at the genetic and pharmacogenetic data in context with patients’ clinical histories. Patients were classified as Type I or Type II alcoholics, according to Cloninger’s typology.

Types of alcoholics

Robert Cloninger, M.D., explored the genetic and environmental factors that led to the development of alcoholism in a Swedish population. In the course of his research, he noted two distinct categories of alcoholics. Cloninger’s typology of alcoholism is briefly summarized as follows:

Type I: Drinks to relieve anxiety; onset after age 25; affects men and women; genetic and environmental etiology; progressive

Type II: Drinks to induce euphoria; onset before age 25; affects mainly men; genetic etiology; not progressive but associated with fighting and arrests

Study findings

Type I alcoholics were found to carry the short allele variation for their serotonin transporter gene. This finding was consistent with previous work that demonstrated that the short variation was associated with chronic anxiety and depression as well as alcoholism. Perhaps this type of alcoholism does develop from “self-medicating” depression and anxiety symptoms over many years.

Type II alcoholics most often carried the long allele variation, which has been associated with psychopathy in other studies. Like Type II alcoholism, psychopathy also is more common in males, is associated with aggression and antisocial behavior, and has a typical onset in adolescence or young adulthood.

The primary purpose of the study was to determine whether genetic markers could be used to predict response to psychotropic medications. Regarding medication response, those with the long allele were more likely to respond to selective serotonin reuptake inhibitors (SSRIs) than those with the short version. Those with the long version also responded to placebos.

Boosting serotonin

People with certain SLC6A4 gene variations, particularly the short allele variation, may be at risk for depression, anxiety and Type I alcoholism throughout their lives. Early identification might help prevent the development of alcoholism. However, antidepressant medication would not be appropriate until symptoms develop, if they develop at all.

Nonpharmacological means for increasing serotonin levels have been described. There are four primary methods:

  • Mood change: Change thought patterns to positive thoughts, ideas and imagery in an effort to lift mood. This can be done through positive thinking strategies, music, psychotherapy, watching comedy, etc.
  • Exposure to sunlight or bright light: Used to treat seasonal affective disorder, this method also is effective for nonseasonal depression.
  • Exercise: Exercise has undisputed antidepressant and anxiolytic effects.
  • Diet: L-tryptophan is a precursor to serotonin and, by increasing tryptophan intake, bioavailability increases and can be converted into serotonin. Milk, egg whites, fish, seaweed, spinach, poultry and bananas are all rich in L-tryptophan. Liver enzymes break down any excess tryptophan. Carbohydrate consumption also increases serotonin levels.
  • Routine genetic analyses are not yet readily available to most people, but anyone can take these basic steps to maintain mental health. These methods are especially important for Type I alcoholics. Maintaining a healthy lifestyle can prevent and treat depression and anxiety. Healthy habits, including the four methods above along with adequate sleep, support long-term sobriety.

If you or someone you love has tried to stop drinking or taking drugs without success, detoxification and treatment can help. New medications and therapies can make the process safe and comfortable. Breaking free from addiction is the first step toward living a healthy and purposeful life.

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About the author

Dana Connolly, Ph.D., is a senior staff writer for Sovereign Health, where she translates current research into practical information. She earned her Ph.D. in research and theory development from New York University and has decades of experience in clinical care, medical research and health education. Sovereign Health is a health information resource, and Dr. Connolly helps to ensure excellence in our model. For more information and other inquiries about this article, contact the author at