5.04 Depressants (Types, Intoxication, and Withdrawal) Psychiatry review for the USMLE Step 1 exam. Depressants decrease neuronal activity in the brain. They can work by stimulating GABAergic neurons or binding to opiate receptors. Common GABA-promoting depressants: alcohol, benzodiazepines, barbiturates, and inhalants. Opioid depressants include heroin and morphine derivatives. Alcohol enhances GABA receptor effects, inhibits glutamate activity, and causes intoxication symptoms such as disinhibition, slurred speech, impaired motor control, lethargy, respiratory depression, and coma. Alcohol withdrawal symptoms include anxiety, agitation, insomnia, nausea/vomiting, tremors, autonomic dysfunction, seizures, and can be life-threatening (delirium tremens). Benzodiazepines bind to the benzodiazepine receptor, enhance GABA effects, and cause intoxication symptoms similar to alcohol. Benzodiazepine withdrawal symptoms include anxiety, agitation, insomnia, and seizures, which are treated with a gradual tapering of the drug. Inhalants depress brain activity and cause symptoms such as disinhibition, paranoia, lethargy, dizziness, ataxia, slurred speech, and high doses can lead to respiratory depression and brain damage. Opioids bind to opioid receptors, reduce pain, improve mood, and cause intoxication symptoms like drowsiness, constricted pupils, seizures, and respiratory depression. Opioid overdose can be reversed with naloxone, an opioid receptor antagonist. Opioid withdrawal symptoms include dysphoria, anxiety, weakness, sweating, dilated pupils, and diarrhea, and can be managed with medications like methadone and buprenorphine. Alcohol withdrawal is an emergency and requires prompt treatment with benzodiazepines.