5.05 Hallucinogens (Types, Intoxication, and Withdrawal)

Psychiatry review for the USME STEP 1 Exam.

• Hallucinogens are a diverse class of drugs that cause hallucinations and other symptoms.
• Common hallucinogens discussed in the podcast are LSD, marijuana, PCP, and ketamine.
• LSD activates serotonin receptors, causing visual and auditory hallucinations, time and reality distortions, mood elevation, and dilation of the pupils. No notable withdrawal symptoms.
• Marijuana acts as a depressant, stimulant, and hallucinogen. THC binds to cannabinoid receptors, increasing neurotransmitters like dopamine and serotonin. Intoxication symptoms include red eyes, anxiety, euphoria, increased appetite, dry mouth, paranoid delusions, and perceived slowed time. Mild withdrawal symptoms include irritability, depression, sleep problems, and decreased appetite. Heavy cannabis use in adolescence is linked to an increased risk of schizophrenia.
• PCP antagonizes NMDA glutamate receptors and activates dopaminergic neurons. Intoxication symptoms include increased pain threshold, agitation, hallucinations, nystagmus, ataxia, and tachycardia. No notable withdrawal symptoms.
• Ketamine is structurally similar to PCP and acts as a milder version. It causes hallucinations and dissociation and is used medically for analgesia.