Alcohol dependence involves daily alcohol consumption, strong urges and cravings for alcohol, difficulty controlling consumption, tolerance to the effects of alcohol and withdrawal symptoms when stopping.
Mechanism of Action
Alcohol is a depressant. It stimulates GABA receptors, which have a relaxing effect on the brain. It also inhibits glutamate receptors (also known as NMDA receptors), causing a further relaxing effect on the electrical activity of the brain (glutamate is an excitatory neurotransmitter).
Long-term alcohol use results in the GABA system becoming down-regulated and the glutamate system becoming up-regulated to balance the effects of alcohol. The patient must continue drinking alcohol, or they will experience unpleasant, uncomfortable and potentially dangerous withdrawal symptoms.
Calculating Alcohol Units
The formula for calculating alcohol units is:
Volume (ml) x Alcohol Content (%) ÷ 1000 = Units of Alcohol
TOM TIP: Calculating alcohol units is a very common exam question. The simplest way is to multiply the volume in litres by the percentage. For example:
- For 750 mls of 12% wine: 0.75 x 12 = 9 units
- For a 25 ml shot of 40% vodka: 0.025 x 40 = 1 unit
- For 500 mls of 5.2% lager: 0.5 x 5.2 = 2.6 units
Recommended Alcohol Consumption
The UK recommendations (Department of Health, updated 2021) on alcohol consumption are:
- Not more than 14 units per week
- Spread evenly over 3 or more days
- Not more than 5 units in a single day
Binge drinking is defined as a single session involving:
- 6 or more units for women
- 8 or more units for men
Pregnant women should avoid alcohol altogether. Alcohol in early pregnancy can lead to:
- Miscarriage
- Small for dates
- Preterm delivery
- Fetal alcohol syndrome
Complications of Alcohol Excess
- Alcohol-related liver disease
- Cirrhosis and its complications (e.g., oesophageal varices, ascites and hepatocellular carcinoma)
- Alcohol dependence and withdrawal
- Wernicke-Korsakoff syndrome (WKS)
- Pancreatitis
- Alcoholic cardiomyopathy
- Alcoholic myopathy, with proximal muscle wasting and weakness
- Increased risk of cardiovascular disease (e.g., stroke or myocardial infarction)
- Increased risk of cancer, particularly breast, mouth and throat cancer
AUDIT Questionnaire
The Alcohol Use Disorders Identification Test (AUDIT) was developed by the World Health Organisation to screen for harmful alcohol use. It involves ten questions with multiple-choice answers and gives a score. A score of 8 or more indicates harmful use.
CAGE Questions
The CAGE questions can be used to screen for harmful alcohol use quickly:
- C – CUT DOWN? Do you ever think you should cut down?
- A – ANNOYED? Do you get annoyed at others commenting on your drinking?
- G – GUILTY? Do you ever feel guilty about drinking?
- E – EYE OPENER? Do you ever drink in the morning to help your hangover or nerves?
Examination
Examination findings with excess alcohol include:
- Smelling of alcohol
- Slurred speech
- Bloodshot eyes
- Dilated capillaries on the face (telangiectasia)
- Tremor
Blood Results
Blood results that can occur with alcohol excess include:
- Raised mean corpuscular volume (MCV)
- Raised alanine transaminase (ALT) and aspartate transferase (AST)
- AST:ALT ratio above 1.5 particularly suggests alcohol-related liver disease
- Raised gamma-glutamyl transferase (gamma-GT) (particularly notable with alcohol-related liver disease)
Alcohol Withdrawal
Alcohol dependence involves a risk of withdrawal symptoms. These range from mild and uncomfortable to delirium tremens.
Withdrawal symptoms occur at different times after alcohol consumption ceases:
- 6-12 hours: tremor, sweating, headache, craving and anxiety
- 12-24 hours: hallucinations
- 24-48 hours: seizures
- 24-72 hours: delirium tremens
Delirium Tremens
Delirium tremens is a medical emergency associated with alcohol withdrawal. Untreated, the mortality rate is 35%.
Long-term alcohol use results in the GABA system becoming down-regulated and the glutamate system becoming up-regulated to balance the effects of alcohol. When alcohol is removed, the GABA system under-functions and the glutamate system over-functions, causing extreme excitability and excessive adrenergic (adrenaline-related) activity.
Delirium tremens presents with:
- Acute confusion
- Severe agitation
- Delusions and hallucinations
- Tremor
- Tachycardia
- Hypertension
- Hyperthermia
- Ataxia (difficulties with coordinated movements)
- Arrhythmias
Managing Alcohol Withdrawal
The CIWA-Ar (Clinical Institute Withdrawal Assessment for Alcohol, revised) tool can be used to score the patient on their withdrawal symptoms and guide treatment.
Chlordiazepoxide (Librium) is a benzodiazepine used to combat the effects of alcohol withdrawal. Diazepam is a less commonly used alternative. It is given orally as a reducing regime titrated to the required dose based on the local alcohol withdrawal protocol (e.g., 10 – 40 mg every 1 – 4 hours). The dose is reduced over 5-7 days.
High-dose B vitamins (Pabrinex) are given intramuscularly or intravenously, followed by long-term oral thiamine. This is used to prevent Wernicke-Korsakoff syndrome.
Long-Term Management
Interventions in the long-term management of alcohol dependence include:
- Specialist alcohol service involvement
- Alcohol detoxification programme
- Oral thiamine to prevent Wernicke-Korsakoff syndrome
- Psychological therapy (e.g., cognitive behavioural therapy)
- Acamprosate, naltrexone or disulfiram are medications used to help maintain abstinence
- Informing the DVLA (their driving licence will be revoked until an extended period of abstinence)
Wernicke-Korsakoff Syndrome
Alcohol excess leads to thiamine (vitamin B1) deficiency. Thiamine is poorly absorbed in the presence of alcohol. Alcoholics often have poor diets and get many of their calories from alcohol. Thiamine deficiency leads to Wernicke’s encephalopathy and Korsakoff syndrome.
Features of Wernicke’s encephalopathy include:
- Confusion
- Oculomotor disturbances (disturbances of eye movements)
- Ataxia (difficulties with coordinated movements)
Features of Korsakoff syndrome include:
- Memory impairment (retrograde and anterograde)
- Behavioural changes
Wernicke’s encephalopathy is a medical emergency with a high mortality rate. Korsakoff syndrome is often irreversible and results in patients requiring full-time institutional care. Prevention and treatment involve thiamine supplementation and abstaining from alcohol.
Last updated June 2024
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