Long-term use was associated with thinning of the posterior cingulate cortex , thickening of the anterior cingulate cortex , and decreased neocortical 5-HT2A receptor binding .
Despite the high method ological heterogeneity and the small sample sizes , the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex
Serotonergic hallucinogens produce alterations of perceptions , mood , and cognition , and have anxiolytic , antidepressant , and antiaddictive properties .
These drugs act as agonists of frontocortical 5-HT2A receptors , but the neural basis of their effects are not well understood .
Thus , we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man .
Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects
Rationale This dose-effect study extends previous observations showing that psilocybin can occasion mystical-type experiences having persisting positive effects on attitudes , mood , and behavior . Objectives This double-blind study evaluated psilocybin ( 0 , 5 , 10 , 20 , 30 mg/70 kg , p.o . ) administered under supportive conditions . Methods Participants were 18 adults ( 17 hallucinogen-naïve ) . Five 8-h sessions were conducted individually for each participant at 1-month intervals . Participants were r and omized to receive the four active doses in either ascending or descending order ( nine participants each ) . Placebo was scheduled quasi-r and omly . During sessions , volunteers used eyeshades and were instructed to direct their attention inward . Volunteers completed question naires assessing effects immediately after and 1 month after each session , and at 14 months follow-up . Results Psilocybin produced acute perceptual and subjective effects including , at 20 and /or 30 mg/70 kg , extreme anxiety/fear ( 39 % of volunteers ) and /or mystical-type experience ( 72 % of volunteers ) . One month after sessions at the two highest doses , volunteers rated the psilocybin experience as having substantial personal and spiritual significance , and attributed to the experience sustained positive changes in attitudes , mood , and behavior , with the ascending dose sequence showing greater positive effects . At 14 months , ratings were undiminished and were consistent with changes rated by community observers . Both the acute and persisting effects of psilocybin were generally a monotonically increasing function of dose , with the lowest dose showing significant effects . Conclusions Under supportive conditions , 20 and 30 mg/70 kg psilocybin occasioned mystical-type experiences having persisting positive effects on attitudes , mood , and behavior . Implication s for therapeutic trials are discussed
Long-term use was associated with thinning of the posterior cingulate cortex , thickening of the anterior cingulate cortex , and decreased neocortical 5-HT2A receptor binding .
Despite the high method ological heterogeneity and the small sample sizes , the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex
Serotonergic hallucinogens produce alterations of perceptions , mood , and cognition , and have anxiolytic , antidepressant , and antiaddictive properties .
These drugs act as agonists of frontocortical 5-HT2A receptors , but the neural basis of their effects are not well understood .
Thus , we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man .