At respected research centers in the United States and other countries, scientists have spent much of their professional lives in drug rehabilitation. It is not because they themselves struggle with addiction. What they are trying to rehabilitate are the drugs.

Their focus is on mind-altering compounds that fell far from grace nearly half a century ago, LSD prominent among them. Along with other psychedelics, it was outlawed by the federal government, damned as bearing a high potential for abuse and offering no accepted medical benefit. But in recent years, researchers have sought to rescue hallucinogens from exile by examining their efficacy in treating certain disorders of the mind, and perhaps even in understanding the nature of consciousness and spirituality.

The work of these scientists now draws the attention of Retro Report, a series of video documentaries that examine major news stories of the past and their enduring significance.

Psychoactive substances, often derived from mushrooms, have been part of human cultures from Central and South America to the Sahara for thousands of years. But there is no need to look that far back; 1938 will do. That was when Albert Hofmann, a Swiss chemist searching for a drug to combat circulatory ailments, happened to synthesize lysergic acid diethylamide: LSD or, more familiarly, acid.