Women who received 15 micrograms of the hallucinogen LSD focused for longer periods and responded faster to visual stimuli than women who received a placebo, according to a small preliminary study. The same effect was not observed in male participants.

The findings were presented on October 12 at the ECNP conference in Munich, Germany, by psychopharmacologist Iva Totmanova of Maastricht University in the Netherlands and her colleagues. The results are “very impressive,” said Conor Murray, a neuroscientist at the University of California, Los Angeles. The study adds to emerging evidence that low doses of LSD may benefit some aspects of cognitive function, he said, while also suggesting that people may differ in their sensitivity to small amounts of psychedelic substances.

What is LSD microdosing?

“Microdosing” generally refers to taking small amounts of psychedelic drugs every few days in an effort to improve mood or cognitive function. A typical LSD microdose is approximately one-tenth of the amount needed to produce a full psychedelic experience.

Although proponents report improved mood and concentration, controlled studies of psychedelic microdosing have produced mixed results.^1,2.

Study examines possible sex differences in LSD’s effects

Previous research by some members of the team, conducted in collaboration with other researchers, suggests that women may feel the effects of drugs more acutely than men.³ To determine whether this difference could be measured objectively through tests of cognitive ability, Totmanova and her colleagues reanalyzed data from an earlier study of low-dose LSD in 53 healthy people.⁴

Women responded 8% faster during an attention test

For the new analysis, the researchers focused on 48 participants. Half received four doses of 15 micrograms of LSD over two weeks, while the others received a placebo. Participants completed a series of cognitive tests measuring sustained attention, information processing and working memory at the beginning of the study, after the first and fourth doses, and at a follow-up visit one week after the final dose.

The study was doubly anonymized, meaning that neither the participants nor the researchers knew who had received LSD.

During a 10-minute sustained-attention test, participants responded to signals displayed on a screen. Women who received LSD microdoses responded 8% faster than women who received the placebo. They also reported feeling less alert, as shown in “The Magic of Microdosing.”

By contrast, low-dose LSD did not significantly change men’s reaction times. The results are preliminary and come from a small analysis, so further research will be needed to determine how reliably LSD microdosing affects attention and whether responses differ between women and men.