"hallucinogens"...,

NYTimes | As a retired clinical psychologist, Clark Martin was well acquainted with traditional treatments for depression, but his own case seemed untreatable as he struggled through chemotherapy and other grueling regimens for kidney cancer. Counseling seemed futile to him. So did the antidepressant pills he tried.

Nothing had any lasting effect until, at the age of 65, he had his first psychedelic experience. He left his home in Vancouver, Wash., to take part in an experiment at Johns Hopkins medical school involving psilocybin, the psychoactive ingredient found in certain mushrooms.

Scientists are taking a new look at hallucinogens, which became taboo among regulators after enthusiasts like Timothy Leary promoted them in the 1960s with the slogan “Turn on, tune in, drop out.” Now, using rigorous protocols and safeguards, scientists have won permission to study once again the drugs’ potential for treating mental problems and illuminating the nature of consciousness.

After taking the hallucinogen, Dr. Martin put on an eye mask and headphones, and lay on a couch listening to classical music as he contemplated the universe.

“All of a sudden, everything familiar started evaporating,” he recalled. “Imagine you fall off a boat out in the open ocean, and you turn around, and the boat is gone. And then the water’s gone. And then you’re gone.”

Today, more than a year later, Dr. Martin credits that six-hour experience with helping him overcome his depression and profoundly transforming his relationships with his daughter and friends. He ranks it among the most meaningful events of his life, which makes him a fairly typical member of a growing club of experimental subjects.

Researchers from around the world are gathering this week in San Jose, Calif., for the largest conference on psychedelic science held in the United States in four decades. They plan to discuss studies of psilocybin and other psychedelics for treating depression in cancer patients, obsessive-compulsive disorder, end-of-life anxiety, post-traumatic stress disorder and addiction to drugs or alcohol.

The results so far are encouraging but also preliminary, and researchers caution against reading too much into these small-scale studies. They do not want to repeat the mistakes of the 1960s, when some scientists-turned-evangelists exaggerated their understanding of the drugs’ risks and benefits.