Why Is Alcohol Addictive?
According to the National Institute on Alcohol Abuse and Alcoholism, alcohol dependence is a condition characterized by impaired control over drinking, compulsive drinking, pre-occupation with drinking, tolerance to alcohol and/or withdrawal symptoms. Alcohol abuse is characterized by failure to fulfill major role obligations at work, school or home, interpersonal social and legal problems and/or drinking in hazardous situations.1 In the U.S., about 17.6 million adults currently suffer from alcohol abuse or dependence. Several million more engage in risky, binge-drinking patterns that can lead to dependence or abuse.2
What Makes Alcohol Addictive?
Drug addictions including alcohol abuse are characterized by greatly diminished executive control over behavior and increased compulsive drug seeking.3 Neurotransmitters are chemical signals that serve as messengers between nerve cells and carriers of the nerve impulse. Dopamine is a type of neurotransmitter that helps control the brain’s reward and pleasure centers. Glutamate is a neurotransmitter that serves as a major mediator of excitatory signals in the central nervous system. It is involved in most aspects of normal brain function including cognition, memory and learning. Both of these play a primary molecular role in alcoholism. The consumption of alcohol increases the release rate of dopamine, thereby inducing feelings of happiness and euphoria. Alcohol consumption inhibits glutamate receptor activity, which results in calmness and reduced anxiety. The feelings of euphoria combined with reduced anxiety create a false sense of security or perceived relief from depression in drinkers.4
A mouse model study published in 2013 found that chronic alcohol exposure shifted behavior control away from the prefrontal cortex, an area of the brain involved in decision-making and control of emotions. When this occurred, the dorsal striatum assumed this responsibility, an area of the brain thought to play a key role in motivation and habit formation. Past studies have shown that alcohol dependent individuals exhibit problems with skills mediated by the prefrontal cortex such as impulse control. Researchers theorize that the shift to increased striatal control over behavior could be a critical step in the progression of alcoholism. These changes could contribute to the emergence of habitual and compulsive patterns of behavior in alcohol abuse, with potential therapies focused on normalizing striatal function.3
Alcohol and Endorphins
In January 2012, research published in the journal Science Translational Medicine showed evidence that pleasure associated with drinking alcohol is caused by endorphins being released to areas of the brain called the nucleus accumbens and the orbitofrontal cortex. Endorphins are small proteins with opiate-like effects that are produced naturally in the brain. The nucleus accumbens is a region of the brain that has been linked to addictive behavior, while the orbitofrontal cortex is associated with decision-making. While animal studies conducted over the last 30 years provided clues to this underlying process, this is the first time that endorphin release in response to alcohol consumption in these two regions of the brain has been directly observed in humans.5,6
Using PET imaging, researchers at the Ernest Gallo Clinic and Research Center at the University of California, San Francisco (UCSF) studied 25 subjects. Thirteen individuals drank heavily and 12 drank moderately. Regardless of the amount the study subjects drank, researchers detected endorphins being released in the brain in response to alcohol consumption. However, there was a more pronounced effect in heavy drinkers. The amount of endorphins being released in the brain’s orbitofrontal cortex was linked to a higher degree of feeling intoxicated. “This indicates that the brains of heavy or problem drinkers are changed in a way that makes them more likely to find alcohol pleasant, and may be a clue to how problem drinking develops in the first place,” said Jennifer Mitchell, PhD, clinical project director at the Gallo Center and an adjunct assistant professor of neurology at UCSF.5,6
How Addictive Is Alcohol?
While the number of people with alcohol dependence and abuse speaks to its highly addictive properties, there is a set of criteria that is used to determine addictive properties of several widely abused substances.7 This is particularly useful for comparison.
- Withdrawal: Presence and severity of characteristic withdrawal symptoms.
- Reinforcement: A measure in human and animal tests of the substance’s ability to cause users to take it repeatedly, and in preference to other substances.
- Tolerance: The amount of a substance needed to satisfy increasing cravings for it, and the level of stable need that is eventually reached.
- Dependence: How difficult it is for a user to quit, the relapse rate, the percentage of people who eventually become dependent, the degree to which the substance is used despite evidence of its harmful effects, and users’ self-rating assigned to their need for the substance.
- Intoxication: Although it is not typically included as a measure of addiction per se, intoxication level is associated with addiction and increases the personal and social damage a substance can incur.7
On a scale of 1 to 6, with 1 being less serious and 6 being the most serious, these are the specific addictive properties of alcohol. In context with other substances, alcohol has a higher withdrawal and intoxication rate than heroin or cocaine.4
- Withdrawal: 6
- Reinforcement: 4
- Tolerance: 4
- Dependence: 3
- Intoxication: 6
Two other statistics that speak to the addictive properties of a substance are annual treatment admissions and mortality, although it is a known fact that only a small percentage of people with alcohol problems receive proper treatment. About 1.5 million adults received treatment for an alcohol use disorder at a specialized facility in 2014 (only 8.9% of adults who needed treatment). This included 1.1 million men and 431,000 women. Nearly 88,000 people die from alcohol-related causes every year in the U.S.8
There are many reasons why a person abuses alcohol including craving attention, gaining social acceptance, alleviating pain, as a coping mechanism for co-occurring mental health disorders and many others. In addition, research points to genetic factors that influence addiction. Scientists are hopeful that pinpointing the area of the brain that responds pleasurably to alcohol consumption will ultimately lead to more efficacious treatment options for alcohol addiction.
- Substance Abuse – What Drives Alcohol Addiction. Wake Forest Baptist Health website. http://www.wakehealth.edu/Health-Central/What-Drives-Alcohol-Addiction/ Updated November 20, 2015. Accessed July 31, 2016.
- Facts About Alcohol. National Council on Alcoholism and Drug Dependence website. https://www.ncadd.org/about-addiction/alcohol/facts-about-alcohol Updated July 25, 2015. Accessed July 31, 2016.
- DePoy L, Daut R, Brigman JL, et al. Chronic alcohol produces neuroadaptations to prime dorsal striatal learning. Proc Natl Acad Sci USA. 2013;110(36):14783-14788. doi:10.1073/pnas.1308198110.
- Alcoholism: A Neurological Perspective. The National High School Journal of Science. http://nhsjs.com/2015/alcoholism-a-neurological-perspective/ Published October 18, 2015. Accessed July 31, 2016.
- Chan AL. Why Alcohol Is So Addictive. Huffington Post. January 13, 2012 http://www.huffingtonpost.com/2012/01/13/alcohol-addictive-endorphins-_n_1202406.html Accessed July 31, 2016.
- Clue as to why alcohol is addicting: Scientists show that drinking releases brain endorphins. Science Daily website. https://www.sciencedaily.com/releases/2012/01/120111155137.htm Published January 12, 2013. Accessed July 31, 2016.
- Addictive Properties of Popular Drugs. Drug War Facts website. http://www.drugwarfacts.org/cms/Addictive_Properties#sthash.OLoVqe5J.dpbs Accessed July 31, 2016.
- Alcohol Facts and Statistics. National Institute on Alcohol Abuse and Alcoholism website. https://www.niaaa.nih.gov/alcohol-health/overview-alcohol-consumption/alcohol-facts-and-statistics Published January 2016. Accessed July 31, 2016.