Psychedelic

Psychedelic refers to a class of psychoactive substances that produce profound changes in perception, mood, and cognition. The term, derived from the Greek psyche meaning mind, was coined in the 1950s by psychiatrist Humphry Osmond to describe substances thought to reveal the mind. In contemporary usage it often denotes serotonergic psychedelics such as LSD, psilocybin, and mescaline, as well as related compounds.

Classic psychedelics produce vivid visual and auditory alterations, altered sense of time, and shifts in thought patterns. Effects vary with dose, setting, and user background. Common experiences include intensified colors, geometric visuals, ego dissolution, and, for some, mystical or spiritual experiences. Physical effects may include dilated pupils, increased heart rate, and nausea.

Most classic psychedelics act primarily as agonists at the brain's serotonin 2A receptors, leading to widespread changes in brain connectivity and information processing. Modern neuroimaging shows increased neural entropy and altered default mode network activity. Therapeutic research in controlled settings has explored potential benefits for depression, anxiety, PTSD, and end-of-life distress, often as part of guided, time-limited therapy accompanied by psychological support.

Psychedelics raise safety considerations, including the risk of distress ('bad trips'), acute anxiety, dangerous behavior in unsupervised settings, and, rarely, persistent perceptual disturbances. There are cautions about interactions with heart or psychiatric conditions and certain medications. Legal status ranges from strict prohibition to decriminalization or medical exemptions in some regions; ongoing clinical trials are governing the official acceptance and use of psychedelic-assisted therapies.