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 .
Psychedelics and Mental Health: A Population Study
Background The classical serotonergic psychedelics LSD , psilocybin , mescaline are not known to cause brain damage and are regarded as non-addictive . Clinical studies do not suggest that psychedelics cause long-term mental health problems .  Psychedelics have been used in the Americas for thous and s of years . Over 30 million people currently living in the US have used LSD , psilocybin , or mescaline . Objective To evaluate the association between the lifetime use of psychedelics and current mental health in the adult population . Method Data drawn from years 2001 to 2004 of the National Survey on Drug Use and Health consisted of 130,152 respondents , r and omly selected to be representative of the adult population in the United States . St and ardized screening measures for past year mental health included serious psychological distress ( K6 scale ) , mental health treatment ( inpatient , outpatient , medication , needed but did not receive ) , symptoms of eight psychiatric disorders ( panic disorder , major depressive episode , mania , social phobia , general anxiety disorder , agoraphobia , posttraumatic stress disorder , and non-affective psychosis ) , and seven specific symptoms of non-affective psychosis . We calculated weighted odds ratios by multivariate logistic regression controlling for a range of sociodemographic variables , use of illicit drugs , risk taking behavior , and exposure to traumatic events . Results 21,967 respondents ( 13.4 % weighted ) reported lifetime psychedelic use . There were no significant associations between lifetime use of any psychedelics , lifetime use of specific psychedelics ( LSD , psilocybin  , mescaline , peyote ) , or past year use of LSD and increased rate of any of the mental health outcomes . Rather , in several cases psychedelic use was associated with lower rate of mental health problems . Conclusion We did not find use of psychedelics to be an independent risk factor for mental health problems
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 .