Cary Grant, who arguably ranks first among Hollywood’s eternal stars, took lysergic acid diethylamide (LSD) at age 55 while under the supervision of his Beverly Hills psychotherapist. Although his friends feared for his carefully cultivated public image, Vanity Fair reports that he instead began lamenting to reporters, “Oh those wasted years, why didn’t I do this sooner?” A University of Dundee study suggests someday other people may join Grant in grieving for lost hours while thinking more generally about time's passage.

The new brain scan study indicates LSD causes decreased activity in the default mode network, which is active when people daydream or think about their past. As might be expected, the Dundee researchers also found LSD alters mental focus; instead of time traveling to the past — at least in their thoughts — the study participants spent most of their time tripping on acid thinking about the present and future. The hallucinogenic drug's positive time perception effects may someday prove useful to the development of therapies for people suffering from depression, one symptom of which is excessive attention on the past.

Albert Hofmann, a chemist working for Sandoz Pharmaceutical, first synthesized LSD in his lab in 1938. Until he accidentally consumed the drug in 1943, he was unaware of its hallucinogenic effects. In the next few decades, researchers began to experiment with the drug, believing it might have psychiatric purposes. Meanwhile, this hallucinogenic became popularized by psychologist Timothy Leary, who encouraged American students to “turn on, tune in, and drop out” during the 1960s.

Among its most commonly reported effects is a shift in the perception of time, say the researchers behind the current study. People who take large doses may also experience a sense of timelessness and dissociation, a state referred to as “ego-disintegration.” Perhaps this is what Grant experienced. According to Vanity Fair, he found himself “turning and turning on the couch” after taking his first dose. Asking his doctor why and wondering when it was going to stop, his doctor answered it would stop when he stopped it. Telling this story to a reporter, Grant commented, “Well, it was like a revelation to me, taking complete responsibility for one’s own actions. I thought 'I’m unscrewing myself.’”

Led by Jana Speth, a doctoral candidate in psychology, the Dundee researchers examined changes in time perception and their relationship with default mode network activity in a study of LSD use. Each of 20 participants was given a dose of LSD in one session and a placebo dose in the other — the sessions were at least two weeks apart — with half randomly assigned to receive the LSD first and half to receive the placebo first. Two hours after receiving their dose, researchers monitored participants’ brain activity using fMRI. Afterwards, participants answered questions about what they had been thinking during the fMRI. The researchers analyzed their responses and quantified how often they thought about the past, present, and future.

What did they discover? Participants thought dramatically less about the past when using LSD as compared to taking a placebo dose. At the same time, fMRI scans indicate significantly lower default mode network activity following LSD. According to the researchers, these results support the view that at least some of the time perception effects are caused by the action of LSD on that particular brain network.

Obsessive focus on the past is a symptom of depression. Additionally, past studies indicate that sufferers tend to have higher than usual levels of default mode network activity. If LSD's chemical components that modulate DMN activity can be identified, the researchers hypothesize it might help depressed people control harmful recollections of the past while moving more gracefully into the future.

Source: Speth J, Speth C, Kaelen M, et al. Decreased mental time travel to the past correlates with default-mode network disintegration under lysergic acid diethylamide. Journal of Psychopharmacology. 2016.