Enduring changes in personality/attitudes , depression , spirituality , anxiety , wellbeing , substance misuse , meditative practice s , and mindfulness were documented .
Mystical experiences , connectedness , emotional breakthrough , and increased neural entropy were related to these long-term changes in psychological functioning .
Finally , with proper screening , preparation , supervision , and integration , limited aversive side effects were noted by study participants .
Research into the basic effects and therapeutic applications of  psychedelic drugs  has grown considerably in recent years .
Yet , pressing questions remain regarding the substances ' lasting effects .
Although individual studies have begun monitoring sustained changes , no study to- date has synthesized this information .
The paradoxical psychological effects of lysergic acid diethylamide (LSD).
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 . METHOD 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 question naire 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
Enduring changes in personality/attitudes , depression , spirituality , anxiety , wellbeing , substance misuse , meditative practice s , and mindfulness were documented .
Mystical experiences , connectedness , emotional breakthrough , and increased neural entropy were related to these long-term changes in psychological functioning .
Finally , with proper screening , preparation , supervision , and integration , limited aversive side effects were noted by study participants .
Research into the basic effects and therapeutic applications of  psychedelic drugs  has grown considerably in recent years .
Yet , pressing questions remain regarding the substances ' lasting effects .
Although individual studies have begun monitoring sustained changes , no study to- date has synthesized this information .