lysergic acid diethylamide (lsd) and hallucinations

   Lysergic acid diethylamide is known under many names, including LSD, LSD-25, and acid. It is usually classified as a semi-synthetic "psychedelic substance of the family of ergot alkaloids, as a "hallucinogen or an "entheogen. The ergo-tamine molecule LSD-25 was synthesized in 1938 out of the parasitic fungus ergot (Claviceps purpurea) by the Swiss chemist and philosopher Albert Hofmann (1906-2008). In 1943 Hofmann drank a crystalline preparation of LSD-25 in a glass of water and discovered its powerful hallucinogenic effects, including an instance of " out-of-body experience (OBE). LSD-25, or LSD for short, proved to be several thousand times as potent as mescaline, making it the hallucinogen of choice for the biomedical and military drug studies carried out during the 1950s and 1960s. Like mescaline, LSD was used to create so-called model psychoses in the hope that these would shed light on the pathophysiology of the major psychotic disorders. Retrospectively, those studies established as many differences as similarities between idiopathic and drug-induced "psychoses. But to their credit, it should be noted that the ensuing biochemical hypotheses of hallucinatory activity roused the interest of researchers studying the neurotransmitter 5-hydroxytryptamine (5-HT) or serotonin. LSD was also used as an experimental therapeutic within the context of LSD psychotherapy for individuals suffering from alcoholism or major psychiatric disorders such as " post-traumatic stress disorder (PTSD) and psychotic disorders. In addition, it was popularized by representatives of the counterculture such as the British-American writer Aldous Leonard Huxley (1894-1963) and the American psychologist and writer Timothy Francis Leary (1920-1996), and soon became a widely used recreational drug. LSD can be administered orally, through the lungs, intravenously, and subcutaneously. Its principal mechanism of action is believed to be its partial agonistic effect on the 5-HT2A serotonin receptor in the CNS, as well as on a large number of the G-protein coupled receptors, including all the dopamine receptor subtypes, and all the adrenoreceptor subtypes. Even when administered in a dosage of 0.5 (ig/kg bodyweight, LSD is capable of mediating a " phantasmagoria of perceptual experiences, commonly referred to as a trip or " LSD trip. These perceptual experiences tend to commence with relatively simple phenomena such as "sparkling (i.e. "hyperchromatopsia), "entoptic phenomena, " phosphenes, "aeropsia, " visual illusions, " geometric visual hallucinations, "aftereffects, afterimage-like "trailing phenomena, " palinopsia, " hyperacusis, " diplacusis, " Gedankenlautwerden, " auditory illusions, " synaesthesias, a variety of perceptual disturbances designated as the " Alice in Wonderland syndrome (which includes " metamorphopsias such as " micropsia, "macropsia, "macroproxiopia, "microtelepsia, " teleopsia, and " plagiopsia, as well as subjective feelings such as derealization, depersonalization, and somatopsychic duality), "body schema illusions, out-of-body experiences, illusory feelings of levitation, and illusory alterations in the passage of time (i.e. "time distortions). The perception of such simple phenomena is enhanced by the closing of the eyes, darkness, and quiet, and altered or interrupted by intrusive sense perceptions such as those stemming from a conversation or physical exercise. "Complex, "compound, and " scenic hallucinations are relatively rare at a dosage of 0.5 (g/kg. Instead, LSD users often report that the extracorporeal world appears strangely animated: for instance, static objects may be perceived as moving relative to one or more spatial dimensions. In addition, LSD tends to mediate feelings ofeuphoria and hyperarousal. At a dosage of 1.0 (g LSD/kg, visual percepts tend to become more intense, developing into kaleidoscopic, scenic hallucinations depicting a distorted fantasy world inhabited by cartoon figures or other bizarre creatures. The physical reactions to LSD are highly variable. They include fever, hypothermia, hyperglucosaemia, tachycardia, perspiration, mydriasis, hypersali-vation, insomnia, " paraesthesias, numbness, muscular weakness or rigidity, hyperreflexia, trembling, and nausea. The long-term effects include a general decrease in higher cortical functioning (which may lead to concentration problems and formal thought disorders), subtle EEG changes, psychotic phenomena, abnormalities in colour perception, "flashbacks, and " hallucinogen-induced persistent perception disorder (HPPD), a condition characterized by the recurrence or persistence of entoptic phenomena and/or visual hallucinations, reminiscent ofthose experienced during a prior episode of intoxication with hallucinogens. LSD use may also entail a so-called bad trip. Occasionally, such 'bad trips' develop into prolonged and/or recurrent psychotic states indistinguishable from those experienced by individuals with a clinical diagnosis of "schizophrenia. On the basis of various studies, the lifetime prevalence of LSD-induced prolonged psychosis is estimated at around 4 in 1,000 individuals. A person intentionally using LSD for the purpose ofexploring the psyche may be called a " psychonaut.

   References

   Abraham, H.D. (1983). Visual phenomenology of the LSD flashback. Archives of General Psychiatry, 40, 884-889.

   Hofmann, A. (1958). Lysergic acid diethylamide and related compounds.In: Chemical concepts of psychosis. Proceedings of the symposium on chemical concepts of Psychosis held at the second international congress of Psychiatry in Zurich, Switzerland, September 1-7, 1957. Edited by Rinkel, M., Denber, C.B. New York, NY: McDowell, Obolensky.

   Koella, W.P. (1982). Semiologie und neurophysi-ologische Grundlagen drogenbedingter Halluz-inationen.In: Halluzinationen bei Epilepsien und ihre Differentialdiagnose.EditedbyKar-bowski, K. Bern: Verlag Hans Huber.

   Rudgley, R. (1998). The encyclopaedia of psy-choactive substances. London: Little, Brown and Company.