A history of psychedelic drug use is associated fewer suicidal thoughts, planning and attempts, according to survey results analyzed by Johns Hopkins and the University of Alabama at Birmingham.

In a national survey of over 190,000 U.S. adults, lifetime use of certain psychedelic drugs was associated with a 19 percent reduced likelihood of psychological distress within the past month, a 14 percent reduced likelihood of suicidal thinking within the past year, a 29 percent reduced likelihood of suicide planning within the past year and a 36 percent reduced likelihood of attempting suicide within the past year. 

The findings suggest that some nonaddictive psychedelic drugs, while illegal, may hold promise for depression, and that these psychedelics' highly restricted legal status should be reconsidered to facilitate scientific studies, says study author Matthew W. Johnson, Ph.D., an associate professor of psychiatry and behavioral sciences at Johns Hopkins.

Current research at Johns Hopkins and several other universities is examining the therapeutic potential of one of the psychedelics, psilocybin, when administered in carefully controlled, monitored medical studies. "These could be breakthrough medical treatments that we've been ignoring for the past 30 years," Johnson says. "We need to carefully examine these cautiously and thoroughly."

For the study, researchers pooled data from five years of results of the National Survey on Drug Use and Health (2008 to 2012) to evaluate the relationship between a history of using certain nonaddictive psychedelic drugs and psychological distress and suicidality. The annual survey, administered by the Substance Abuse and Mental Health Services Administration of the U.S. Department of Health and Human Services, estimates the prevalence of substance use and mental illness in the general U.S. civilian noninstitutionalized population. The study focused on respondents with a history of using nonaddictive psychedelic drugs, which interact with certain serotonin receptors in the brain.

Of 191,382 respondents, 27,235 reported lifetime use of one or more of these psychedelics, primarily psilocybin and LSD. Lifetime use was concentrated among 26- to 64-year-olds and was more common among men; non-Hispanic whites and Native Americans/Alaska Natives; those with greater education and income; individuals who were divorced, separated or who had never married; those with greater self-reported engagement in risky behavior; and those who reported lifetime illicit use of other substances. Among users of these psychedelic drugs, only 240 said they never tried any other illicit drug.

In addition, 12,657 respondents reported psychological distress within the past month, 10,445 reported suicidal thinking within the past year, 3,157 reported suicidal planning within the past year and 1,716 reported suicidal attempt within the past year.

Using statistical methods that controlled for factors such as age, gender, income, education and other drug use, researchers found that lifetime use of these drugs was associated with a decreased likelihood of past-month psychological distress and past-year suicidal thinking, planning, and attempts. Conversely, lifetime use of other illicit substances was largely associated with an increase in these harms, "which is consistent with the fact that these other drugs, unlike classic psychedelics, are addictive," Johnson says.  "Our general societal impression of these drugs is they make people go crazy or are associated with psychological harm, but our data point to the potential psychological benefits from these drugs."

Because this is a weak observational study, there is no evidence that psychedelics caused these effects - those who chose to use psychedelics may have been psychologically healthier before using these drugs. Nonetheless, the authors believe the results reflect a benefit from psychedelics. The use of nonaddictive psychedelic drugs may exacerbate schizophrenia or other psychotic disorders and can sometimes elicit feelings of anxiety, fear, panic and paranoia, which can lead to dangerous behavior, Johnson says. But these instances of individual harm, while serious, may not stand out in the survey data because they occur less often than the positive outcomes that some people experience. 

Published in the Journal of Psychopharmacology. The study was co-authored by Peter S. Hendricks, Christopher B. Thorne, C. Brendan Clark and David W. Coombs of the University of Alabama at Birmingham.