Alcohol-Related Disorders

Learning Objectives

  • Explain how depressants impact nervous system activity, including the short- and long-term physiological and psychological effects of alcohol
  • Describe the diagnostic features, development, and risk factors of alcohol use disorder, alcohol intoxication, and alcohol withdrawal

Understanding Alcohol

Ethanol, which we commonly refer to as alcohol, is in a class of psychoactive drugs known as depressants (Figure 1). A depressant is a drug that tends to suppress central nervous system activity. Other depressants include barbiturates and benzodiazepines. Barbiturates and benzodiazepines share in common their ability to serve as agonists of the gamma-aminobutyric acid (GABA) neurotransmitter system. Because gamma-aminobutyric acid (GABA) has a quieting effect on the brain, gamma-aminobutyric acid (GABA) agonists also have a quieting effect; these types of drugs are often prescribed to treat both anxiety and insomnia.

An illustration of a GABA-gated chloride channel in a cell membrane shows receptor sites for barbiturate, benzodiazepine, GABA, alcohol, and neurosteroids, as well as three negatively-charged chloride ions passing through the channel. Each drug type has a specific shape, such as triangular, rectangular or square, which corresponds to a similarly shaped receptor spot.

Figure 1. The GABA-gated chloride (Cl-) channel is embedded in the cell membrane of certain neurons. The channel has multiple receptor sites where alcohol, barbiturates, and benzodiazepines bind to exert their effects. The binding of these molecules opens the chloride channel, allowing negatively-charged chloride ions (Cl-) into the neuron’s cell body. Changing its charge in a negative direction pushes the neuron away from firing; thus, activating a GABA neuron has a quieting effect on the brain.

Acute alcohol administration results in a variety of changes to consciousness. Alcohol intoxication is measured for legal and medical uses in terms of blood alcohol content (BAC). A blood alcohol content (BAC) of 0.10 (0.10% or one-tenth of 1%) means that there are 0.10 grams of alcohol for every 100 milliliter of blood. While a blood alcohol content (BAC) of 0.0 is sober, in the United States, a BAC of 0.08 is legally intoxicated, and any level above that is considered very impaired. BAC levels above 0.40 are potentially fatal. At rather low doses, alcohol use is associated with feelings of euphoria. As the dose increases, people report feeling sedated. Generally, alcohol is associated with decreases in reaction time and visual acuity, lowered levels of alertness, and reduction in behavioral control. With excessive alcohol use, a person might experience a complete loss of consciousness and/or difficulty remembering events that occurred during a period of intoxication (McKim & Hancock, 2013). In addition, if a pregnant woman consumes alcohol, her infant may be born with a cluster of birth defects and symptoms collectively called fetal alcohol spectrum disorder (FASD) or fetal alcohol syndrome (FAS).

With repeated use of many central nervous system depressants, such as alcohol, a person becomes physically dependent upon the substance and will exhibit signs of both tolerance and withdrawal. Psychological dependence on these drugs is also possible. Therefore, the abuse potential of central nervous system depressants is relatively high.

Drug withdrawal is usually an aversive experience, and it can be a life-threatening process in individuals who have a long history of very high doses of alcohol and/or barbiturates. A history of high doses of substances is of such concern that people who are trying to overcome addiction to these substances should only do so under medical supervision.

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Alcohol-Related Disorders

Alcoholism, more appropriately referred to as alcohol use disorder (AUD), is, broadly, any drinking of alcohol that results in mental and/or physical health problems ranging anywhere from mild and imperceptible without special testing to severe and grossly overt. The disorder was previously divided into two types: alcohol abuse and alcohol dependence. The DSM–5 integrates the two DSM–4 disorders, alcohol abuse and alcohol dependence, into a single disorder called alcohol use disorder (AUD) with mild, moderate, and severe sub-classifications.

In a medical context, alcoholism is said to exist when two or more of the following conditions are present: a person drinks large amounts of alcohol over a long time period, a person has difficulty cutting down, acquiring and drinking alcohol takes up a great deal of their time, alcohol is strongly desired, usage results in not fulfilling responsibilities, usage results in social problems, usage results in health problems, usage results in risky situations, withdrawal occurs when stopping, and alcohol tolerance has occurred with use. Under DSM–5, anyone meeting any two of the 11 criteria (shown in Table 1) during the same 12-month period would receive a diagnosis of AUD. The severity of AUD—mild, moderate, or severe—is based on the number of criteria met.

The DSM-5 classifies alcoholism as alcohol-use disorder, alcohol intoxication, and alcohol withdrawal. Alcohol intoxication is diagnosed by the recent ingestion of alcohol and clinically significant problematic behavioral or psychological changes (e.g., inappropriate sexual or aggressive behavior, mood lability, impaired judgment) that developed during, or shortly after, alcohol ingestion. One (or more) of the following signs or symptoms develop during, or shortly after, alcohol use:

  • slurred speech
  • incoordination
  • unsteady guilt
  • nystagmus
  • impairment in attention or memory
  • stupor or coma

Alcohol intoxication is a risk factor in some cases of catastrophic injury, in particular for unsupervised recreational activity. A study in the province of Ontario, Canada, based on epidemiological data from 1986, 1989, 1992, and 1995 revealed that 79.2% of the 2,154 catastrophic injuries recorded for the study were preventable, of which 346 (17%) involved alcohol consumption. Alcohol intoxication is the negative health effects due to the recent drinking of ethanol (alcohol). When severe, it may become a medical emergency. Some effects of alcohol intoxication, such as euphoria and lowered social inhibition, are central to alcohol’s desirability.

Alcohol withdrawal describes a set of symptoms that can occur following a reduction in alcohol use after a period of excessive use. Symptoms typically include anxiety, shakiness, sweating, vomiting, fast heart rate, and a mild fever. More severe symptoms may include seizures, seeing or hearing things that others do not, and delirium tremens (DTs). Delirium tremens (DTs) may include alcohol hallucinosis in which patients have transient visual, auditory, or tactile hallucinations, but are otherwise clear. Withdrawal seizures are seizures that occur within 48 hours of alcohol cessations and occur either as a single generalized tonic-clonic seizure or as a brief episode of multiple seizures. Symptoms typically begin around six hours following the last drink, are worst at 24 to 72 hours, and improve by seven days. Delirium tremens describe a hyperadrenergic state, disorientation, tremors, diaphoresis, and impaired attention/consciousness. Alcohol withdrawal may occur in those who are alcohol dependent. This may occur following a planned or unplanned decrease in alcohol intake.

In the Western world, about 15% of people have problems with alcoholism at some point in time. About half of people with alcoholism will develop withdrawal symptoms upon reducing their use, with 4% developing severe symptoms. Among those with severe symptoms, up to 15% die. Benzodiazepines are effective for the management of symptoms as well as the prevention of seizures. Certain vitamins are also an important part of the management of alcohol withdrawal syndrome. In those with lesser symptoms, treatment at home may be possible with daily visits with a health care provider.

Diagnostic Criteria for Alcohol Use Disorder


Table 1. DSM–5 Criteria for Alcohol Use Disorder.
In the past year, have you:
The presence of at least 2 of these symptoms indicates Alcohol Use Disorder (AUD).
The severity of the AUD is defined as: Mild: The presence of 2 to 3 symptoms
Moderate: The presence of 4 to 5 symptoms
Severe: The presence of 6 or more symptoms
Had times when you ended up drinking more, or longer, than you intended?
More than once wanted to cut down or stop drinking, or tried to, but couldn’t?
Spent a lot of time drinking? Or being sick or getting over other aftereffects?
Wanted a drink so badly you couldn’t think of anything else
Found that drinking—or being sick from drinking—often interfered with taking care of your home or family? Or caused job troubles? Or school problems?
Continued to drink even though it was causing trouble with your family or friends?
Given up or cut back on activities that were important or interesting to you, or gave you pleasure, in order to drink?
More than once gotten into situations while or after drinking that increased your chances of getting hurt (such as driving, swimming, using machinery, walking in a dangerous area, or having unsafe sex)?
Continued to drink, even though it was making you feel depressed or anxious or adding to another health problem? Or after having had a memory blackout?
Had to drink much more than you once did to get the effect you want? Or found that your usual number of drinks had much less effect than before?
Found that when the effects of alcohol were wearing off, you had withdrawal symptoms, such as trouble sleeping, shakiness, restlessness, nausea, sweating, a racing heart, or a seizure? Or sensed things that were not there?

Alcohol use can affect all parts of the body, but it particularly affects the brain, heart, liver, pancreas, and immune system. Alcoholism can result in mental illness, delirium tremens, Wernicke-Korsakoff syndrome (memory loss), irregular heartbeat, an impaired immune response, liver cirrhosis, and increased cancer risk. Drinking during pregnancy can result in fetal alcohol syndrome disorders. Women are generally more sensitive than men to the harmful effects of alcohol, primarily due to their smaller body weight, lower capacity to metabolize alcohol, and higher proportion of body fat. In a small number of individuals, prolonged, severe alcohol abuse ultimately leads to frank dementia.


Environmental factors and genetics are two factors affecting risk for alcoholism, with about half the risk attributed to each. Someone with a parent or sibling with alcoholism is three to four times more likely to become an alcoholic themselves, but only a minority of them do. Environmental factors include social, cultural, and behavioral influences. High stress levels and anxiety, as well as alcohol’s inexpensive cost and easy accessibility, increase the risk. People may continue to drink partly to prevent or improve symptoms of withdrawal. After a person stops drinking alcohol, they may experience a low level of withdrawal lasting for months. Medically, alcoholism is considered both a physical and mental illness. Questionnaires are usually used to detect possible alcoholism. Further information is then collected to confirm the diagnosis.

Prevention of alcoholism may be attempted by regulating and limiting the sale of alcohol (particularly to minors), taxing alcohol to increase its cost, and providing education and inexpensive treatment. Prohibition did not work. Treatment of alcoholism may take several forms. Due to medical problems that can occur during withdrawal, alcohol detoxification should be carefully controlled. One common method involves the use of benzodiazepine medications, such as diazepam. These can be either given while admitted to a health care institution or occasionally while a person remains in the community with close supervision. Mental illness or other addictions may complicate treatment. After detoxification, various forms of individual or group therapy or support groups can help keep a person from returning to drinking. One commonly used form of support is the group Alcoholics Anonymous. The medications acamprosate, disulfiram, or naltrexone may also be used to help prevent further drinking.

Watch It

In this video, a medical team discusses alcohol use disorder and we are introduced to a man who explains his own experiences and struggles with alcohol.

You can view the transcript for “Experts Apply DSM-5 Criteria for Alcohol Use Disorder” here (opens in new window).


The World Health Organization has estimated that as of 2016, there were 380 million people with alcoholism worldwide (5.1% of the population over 15 years of age). As of 2015 in the United States, about 17 million adults (7%) and 0.7 million (2.8%) of those from 12 to 17 years of age are affected. Alcoholism is most common among males and young adults. Geographically, it is least common in Africa (1.1% of the population) and has the highest rates in Eastern Europe (11%). Alcoholism directly resulted in 139,000 deaths in 2013, up from 112,000 deaths in 1990. A total of 3.3 million deaths (5.9% of all deaths) are believed to be due to alcohol. Alcoholism reduces a person’s life expectancy by approximately ten years.

Key Takeaways: Alcohol Use Disorder

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depressant: drug that tends to suppress central nervous system activity