Alcoholism, a hereditary disease?

Although the history of alcohol consumption and alcoholism is as old as human civilization, it remains difficult to provide a clear answer as to why only a minority of alcohol users slide into alcoholism. Based on available data, it can be said that, like chronic diseases such as diabetes and hypertension, genetic factors and life circumstances also play a role in alcoholism.

Evidence of the Influence of Genetic Factors

Scientists have concluded that genetic factors contribute to the onset of alcoholism based on four types of studies.

1. Family Studies

Studies show that the likelihood of alcoholism occurring in family members and children of alcoholics is four times and nine times higher, respectively, compared to those without a family history of alcoholism. Research also suggests that individuals with a family history of alcoholism experience less intoxication when consuming alcohol and have a relatively smaller amygdala, the part of the brain that determines emotional intensity in addiction.

It is noteworthy, however, that more than half of the children of alcoholics do not develop this disorder. Factors such as how many relatives have alcoholism, the severity of their condition, and the closeness of blood relations determine whether an individual will develop alcoholism.

These studies alone are insufficient to determine whether the spread of alcoholism within families is due to genetic reasons or the influence of the home environment and the tendency to imitate family members. For that, studies on twins or adoptees are necessary.

2. Twin Studies

There are two types of twins: identical twins, who are 100% genetically similar, and fraternal twins, who share the same genetic similarity as siblings born from different pregnancies. If one identical twin has a hereditary disease, the likelihood of the other twin being affected is much higher compared to fraternal twins.

Several studies have clearly shown that if one twin has alcoholism, the likelihood of the other twin developing it is significantly higher in identical twins than in fraternal twins. These findings provide strong evidence that genetic factors play a role in alcoholism.

3. Adoption Studies

These studies compare the likelihood of alcoholism in children of alcoholics raised by non-alcoholic adoptive parents and children of non-alcoholics raised by alcoholic adoptive parents. If the family environment is more influential in the onset of alcoholism, the disorder should be more prevalent among children raised by alcoholics. Conversely, if genetic factors are more significant, the disorder should be more common among biological children of alcoholics.

Such studies have found that the likelihood of alcoholism in the biological children of alcoholics is two to four times higher. This further underscores the role of heredity in alcoholism.

4. Animal Studies

Studies conducted on laboratory animals, particularly mice, indicate that factors such as the degree of intoxication experienced when consuming alcohol and the withdrawal symptoms when alcohol use is stopped are controlled by certain genes.

Genes Leading to Alcoholism

{xtypo_quote_right}The disorder labeled as alcoholism is, in truth, a cluster of several diseases with similar symptoms.{/xtypo_quote_right}The disorder labeled as alcoholism is, in truth, a cluster of several diseases with similar symptoms. Each of these disorders may have its own genetic causes, making the task of identifying the genes responsible for alcoholism particularly challenging. However, based on available evidence, the following genes are generally believed to influence the onset of alcoholism. While some genes increase the risk of alcoholism, others may reduce the likelihood of an individual sliding into excessive drinking.

1. Genes Determining the Rate of Alcohol Metabolism

The enzyme alcohol dehydrogenase converts a significant portion of alcohol in the body into acetaldehyde. Even small accumulations of acetaldehyde in the body can cause problems such as facial flushing, increased heart rate, and nausea. However, another enzyme, aldehyde dehydrogenase, quickly breaks down acetaldehyde, which is why drinkers typically do not experience these discomforts.

Individuals with genetically low levels of aldehyde dehydrogenase may experience a buildup of acetaldehyde in their blood when consuming alcohol, leading to the aforementioned discomforts. This significantly reduces their likelihood of sliding into excessive drinking. About half of the populations of Japan, China, and Korea are born with this deficiency in aldehyde dehydrogenase.

Some Asian populations have a highly active variant of alcohol dehydrogenase. When these individuals consume alcohol, the enzyme rapidly converts it into acetaldehyde, causing discomfort. As a result, this group is also less likely to develop alcoholism.

2. Genes Determining Personality Traits

It has been proven that individuals with impulsive or low self-control traits are more likely to develop alcoholism, and certain genes play a role in shaping these traits. Similarly, studies suggest that genes influencing how the brain responds to stress, pleasure, and rewards may also contribute to the onset of alcoholism.

3. Genes Determining Alcohol's Impact on the Brain

{xtypo_quote_left}Genetic factors also play a role in determining who will benefit from certain medications used to treat alcoholism.{/xtypo_quote_left}Some individuals experience intoxication only after consuming large quantities of alcohol, and this is also due to genetic reasons. Studies show that children of alcoholics do not feel as intoxicated as others when drinking. Such individuals are more likely to associate with heavy drinkers, consume alcohol excessively, and face physical and mental health problems due to drinking.

For others, alcohol provides more pleasure than expected. This is believed to be due to variations in the levels of dopamine, a neurotransmitter, in certain neural pathways in their brains. Studies suggest that alcoholics and heavy smokers have a specific variant of dopamine receptors in their nerves. All these traits are genetically determined.

In addition, genetic factors are believed to influence how much damage alcohol causes to organs like the liver and brain, as well as who will benefit from certain medications used to treat alcoholism.

Characteristics of Genetically Influenced Alcoholism

{xtypo_quote_left}In most patients, both genetic factors and environmental circumstances contribute to the onset of alcoholism.{/xtypo_quote_left} In most patients, both genetic factors and environmental circumstances contribute to the onset of alcoholism. Alcoholism with a strong genetic component is often referred to as Type II alcoholism. Predominantly found in men, the symptoms of this disorder include:

• Behavioral issues such as aggression and attention deficits from childhood
• Early initiation of alcohol use before the age of 15
• Personality disorders like aggressiveness and lack of empathy
• Criminal tendencies
• More severe alcoholism
• Drinking primarily for intoxication (unlike Type I alcoholics, who may drink to relieve tension)
• Greater difficulty in quitting alcohol

Precautions for Those with a Family History of Alcoholism

{xtypo_quote_right}Experts currently do not recommend genetic testing for those wishing to assess their risk of developing alcoholism.{/xtypo_quote_right}This article does not imply that all family members of alcoholics are destined to become heavy drinkers. Generally, available data suggest that 60% of an individual's risk of alcoholism is determined by their genes, while the remaining 40% is influenced by life circumstances. Therefore, adopting appropriate lifestyle changes and precautions can help prevent the onset of alcoholism. Below are some recommendations for family members of alcoholics:

1. Learn techniques to manage stress, anger, and sleep deprivation to avoid turning to alcohol for self-medication.
2. Avoid alcohol consumption before reaching adulthood. The brain reaches full maturity only around the ages of 20-25. Drinking before this age increases the likelihood of developing alcoholism later in life.
3. Avoid social circles where heavy drinking is common.
4. Do not entertain the notion of occasional moderate drinking. Those with a family history of alcoholism will find it very difficult to maintain controlled drinking.
5. Seek expert help at the first sign of losing control over drinking.

Many aspects of this subject remain unclear. Therefore, experts currently do not recommend genetic testing for those wishing to assess their risk of developing alcoholism. Analyzing one's family history to determine the presence of alcoholism is the most insightful, cost-effective, simple, and practical method available today.

(Published in the February 2012 issue of Mathrubhumi Health Magazine.)

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