Alcohol withdrawal syndrome (AWS), characterized by symptoms of brain hyperexcitability
and autonomic hyperactivity, occurs in persons who abruptly stop or substantially decrease
their intake of alcohol (ethanol) after chronic and heavy drinking. AWS usually occurs in
individuals who had been drinking heavily for long periods of time, typically months or
years. Symptoms are variable and range in severity from mild to life-threatening.
Alcohol is a CNS depressant; however, chronic alcohol abuse induces adaptive changes
in brain homeostasis characterized by downregulation of receptors for the main inhibitory
neurotransmitter, gamma-aminobutyric acid [GABA] and upregulation of receptors for
excitatory neurotransmitters. After abrupt cessation of alcohol consumption, the brain
responds by going into a hyperexcitable state that is responsible for most of the symptoms
of AWS. The severity of symptoms depends on the dose, frequency, and duration of
alcohol consumption and history of previous episodes of AWS. Mild symptoms of AWS
include nervousness, anxiety, mood instability, fatigue, and irritability; moderate symptoms
include nausea and vomiting, sweating, insomnia, tachycardia, tremor, headache, and loss
of appetite; severe symptoms include blackouts, agitation, and fever. Although AWS is
usually mild, it can lead to potentially fatal complications, including delirium tremens (DTs)
(see Quick Lesson About ... Alcohol Withdrawal Delirium ) and alcohol-related seizures
(see Quick Lesson About ... Alcohol Withdrawal Seizures ). Other potential complications
associated with chronic alcohol abuse include nutritional deficiencies and electrolyte
imbalances (e.g., hyponatremia, hypokalemia, hypomagnesaemia, hypophosphatemia),
which increase the risk of seizures, arrhythmias, and brain damage.