title: The paradoxical psychological effects of lysergic acid diethylamide (LSD).
abstract: BACKGROUND
  Lysergic acid diethylamide (LSD) is a potent serotonergic hallucinogen or psychedelic that modulates consciousness in a marked and novel way. This study sought to examine the acute and mid-term psychological effects of LSD in a controlled study.
  
  
  METHODS
  A total of 20 healthy volunteers participated in this within-subjects study. Participants received LSD (75 µg, intravenously) on one occasion and placebo (saline, intravenously) on another, in a balanced order, with at least 2 weeks separating sessions. Acute subjective effects were measured using the Altered States of Consciousness questionnaire and the Psychotomimetic States Inventory (PSI). A measure of optimism (the Revised Life Orientation Test), the Revised NEO Personality Inventory, and the Peter's Delusions Inventory were issued at baseline and 2 weeks after each session.
  
  
  RESULTS
  LSD produced robust psychological effects; including heightened mood but also high scores on the PSI, an index of psychosis-like symptoms. Increased optimism and trait openness were observed 2 weeks after LSD (and not placebo) and there were no changes in delusional thinking.
  
  
  CONCLUSIONS
  The present findings reinforce the view that psychedelics elicit psychosis-like symptoms acutely yet improve psychological wellbeing in the mid to long term. It is proposed that acute alterations in mood are secondary to a more fundamental modulation in the quality of cognition, and that increased cognitive flexibility subsequent to serotonin 2A receptor (5-HT2AR) stimulation promotes emotional lability during intoxication and leaves a residue of 'loosened cognition' in the mid to long term that is conducive to improved psychological wellbeing.
authors: Imperial College London,Centre for Neuropsychopharmacology,Division of Brain Sciences,Faculty of Medicine,London,UK.
authors: R L
authors: RL
authors: Carhart-Harris
authors: Imperial College London,Centre for Neuropsychopharmacology,Division of Brain Sciences,Faculty of Medicine,London,UK.
authors: M
authors: M
authors: Kaelen
authors: Imperial College London,Centre for Neuropsychopharmacology,Division of Brain Sciences,Faculty of Medicine,London,UK.
authors: M
authors: M
authors: Bolstridge
authors: Department of Psychiatry,The University of Bristol,Bristol,UK.
authors: T M
authors: TM
authors: Williams
authors: Imperial College London,Centre for Neuropsychopharmacology,Division of Brain Sciences,Faculty of Medicine,London,UK.
authors: L T
authors: LT
authors: Williams
authors: Institute of Psychiatry, Psychology & Neuroscience,Department of Psychology,King's College London,London,UK.
authors: R
authors: R
authors: Underwood
authors: The Beckley Foundation,Beckley Park,Oxford,UK.
authors: A
authors: A
authors: Feilding
authors: Imperial College London,Centre for Neuropsychopharmacology,Division of Brain Sciences,Faculty of Medicine,London,UK.
authors: D J
authors: DJ
authors: Nutt
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects*; D018592:Cross-Over Studies; D006213:Hallucinogens / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008238:Lysergic Acid Diethylamide / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D010549:Personal Satisfaction; D044402:Receptor, Serotonin, 5-HT2A / Q000187:drug effects*; D055815:Young Adult
chemical_list: D006213:Hallucinogens; D044402:Receptor, Serotonin, 5-HT2A; D008238:Lysergic Acid Diethylamide
keywords: LSD; mood; psychedelics; psychosis; serotonin