Microdosing LSD shows some cognitive benefits — but only for women

In a small preliminary study, women who received 15 micrograms of the psychedelic drug LSD focused for longer periods and responded faster to a stimulus than did those who were given a placebo. This effect was not observed for male participants.

The study was presented on 12 October at a neuropsychology meeting, the ECNP Congress in Munich, Germany, by psychopharmacologist Iva Totomanova at Maastricht University in the Netherlands and her colleagues. The findings are “very cool”, says Conor Murray, a neuroscientist at the University of California, Los Angeles. “This work is a notable addition to emerging evidence that low doses of LSD have cognitive benefits.” The data also suggest that some people might be more sensitive than others to small quantities of psychedelics, he adds.

Brain boost

'Microdosing' involves taking small doses of a psychedelic every few days, purportedly to improve mood and cognitive function. A typical microdose of LSD can be roughly one-tenth of the amount needed to produce a full psychedelic experience. Although proponents report experiencing a brighter mood and sharper focus, controlled studies on the effects of microdosing have shown mixed results^1,2.

Previous research from some members of the team, in collaboration with others, suggests that women feel the drug’s influence more strongly than men³. To find out whether this can be measured objectively, for example in tests of cognitive performance, Totomanova and her colleagues reanalysed data from a previous study that explored the effects of low doses of LSD on 53 healthy people⁴.

For the new analysis, the researchers focussed on 48 participants. Half of the participants received 15 micrograms of LSD four times over two weeks; others received a placebo. The participants completed a set of cognitive tests assessing sustained attention, information processing and working memory at the beginning of the study, after the first and fourth doses and at a follow-up a week after the last dose. The study was double-anonymized: neither the participants nor the researchers knew who had received the drug.

During the 10-minute test of sustained attention, which involved responding to signals as they appeared on a screen, women who had taken a microdose of LSD reacted 8% faster than those who had been given a placebo. They also experienced fewer attention lapses (see ‘Microdose magic’). By contrast, a microdose of LSD didn’t have much effect on men's reaction time.

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