The research, conducted by a team at the University of Maastricht and presented at the annual congress of the European College of Neuropsychopharmacology (ECNP) in Munich, examined how microdosed LSD influenced three domains of mental performance: sustained attention, information processing speed, and working memory. In a randomised, double-blind, placebo-controlled design, 48 healthy volunteers, 24 women and 24 men with an average age of 36.9 years, were assigned to receive either an inert placebo or four doses of LSD over a two-week period. Each dose contained 15 micrograms, a quantity well below the threshold at which the characteristic psychedelic effects of LSD typically appear, which the researchers note generally requires more than 60 micrograms. Neither participants nor investigators knew who had received the active drug until the entire study had been completed, a design feature that helps guard against expectation effects, which are known to be particularly powerful in psychedelic research.

Participants were tested on four occasions: at the start of the study, after the first dose, after the fourth and final dose, and again at a follow-up session. Across the battery of tasks, one result stood out clearly. In a test of sustained attention, in which participants had to watch a screen and respond as quickly as possible whenever a signal appeared, the women who received LSD performed markedly better than the women who received placebo. Their reactions to the visual stimulus were about 8 percent faster, averaging 308 milliseconds under LSD compared with 335 milliseconds under placebo. Perhaps more strikingly, the treated women committed an average of 2.3 lapses in attention, a common laboratory measure of momentary losses in focus, while women in the placebo group averaged 4.7 lapses, roughly twice as many.

Crucially, this improvement in sustained attention was not a one-off observation confined to a single testing session. The advantage for the LSD group on attentional lapses appeared after the very first dose, persisted after repeated dosing across the two-week period, and could still be detected at follow-up. In contrast, the men in the study showed no comparable benefit. Their performance on the sustained attention task under microdosed LSD was not meaningfully different from their performance under placebo. The dissociation between the sexes was the most notable finding of the study, and it suggests that pooled analyses, which collapse results across men and women, may obscure real effects that apply only to a subset of participants.

Lead researcher Iva Totomanova of the University of Maastricht emphasized that the finding must be interpreted with care. She explained that the team examined the effect of LSD on three different cognitive tasks, and that the clearest result concerned how women sustain attention. For the information processing and working memory tasks, she noted, the results were not as clear-cut, which may help explain why sex-related effects have been missed in previous studies. She was careful to state that the work does not show that low-dose LSD generally improves cognition, nor that women are generally more responsive to LSD than men. Instead, she said, the results point to a more cautious message: effects may depend on the person, the specific cognitive task being measured, and the circumstances of use. In her view, a better research question may be who responds to microdosing, and under what conditions.

The study is, importantly, a re-analysis of data from an earlier completed trial rather than an experiment designed from the outset to probe sex differences. The authors acknowledge this limitation openly. They note that confirming the finding will require research specifically built to examine how sex shapes the response to psychedelics, for example by measuring hormone concentrations in the blood and accounting for menstrual phase and the use of hormonal contraceptives. Such factors, which vary systematically over time and between individuals, could plausibly interact with serotonergic drugs like LSD and may help explain why men and women responded differently in this dataset.

The biological rationale for such a sex difference remains an open question, but it is not implausible. LSD acts primarily on serotonin receptors, particularly the 5-HT2A subtype, and serotonergic signalling is known to interact with ovarian hormones such as estrogen, which themselves modulate attention and cognitive performance. Differences in hormone state, drug metabolism, or baseline attentional profiles could all contribute to a scenario in which women show measurable gains while men do not. The finding that women given placebo tended to have slower reaction times and more attention lapses than men on the same task also suggests that the two groups started from different baselines, leaving more room for improvement among the women.

The broader context for this work is a field marked by conflicting results. Observational surveys of people who microdose on their own have often reported striking benefits for focus and mood, but such self-selected samples are vulnerable to expectation effects. Laboratory-based placebo-controlled trials, by contrast, have frequently found that improvements occur in both the active drug and placebo groups, suggesting that much of the perceived benefit of microdosing may be driven by belief rather than pharmacology. The Maastricht study is notable because the participants did not know whether they had received LSD or placebo, and because a genuine drug-by-sex interaction emerged despite the small sample. Totomanova observed that researchers are beginning to see that people respond to psychedelics in different ways, and that with psychedelic pharmaceuticals, personalised medicine looks likely to be important.

Independent experts reacted to the findings with measured interest. Dr Mikkel Højlund of the University of Southern Denmark, who was not involved in the work, commented that microdosing of psychedelics has received a great deal of media attention, so testing it in a proper research context is important for advancing knowledge on the subject. He noted that even though the study was double-blind and placebo-controlled, the researchers themselves are cautious, describing it as a small study with several variables, but one that merits further work on a bigger scale. His assessment echoes the authors’ own framing: the result is promising and scientifically interesting, but it is a signal from a pilot dataset rather than a definitive demonstration.

As interest in psychedelic therapeutics continues to grow, studies of this kind underscore a central lesson of modern psychopharmacology: average effects across a mixed population can hide effects that are real and substantial for particular groups. The Maastricht team’s data suggest that low-dose LSD may meaningfully enhance sustained attention in women, roughly halving attentional lapses and speeding responses by about 8 percent, while leaving men untouched on the same measure. If future trials designed specifically to test sex differences confirm the pattern, and if the mechanisms behind it can be identified, microdosing research may shift away from broad claims about universal cognitive enhancement and toward a more refined, individualised picture of who benefits, on which tasks, and under what circumstances. Until then, the researchers caution, the findings should be treated as preliminary evidence that the answer to whether microdosing works may well be: it depends on who is asking.

Subject of Research: Sex differences in the cognitive effects of LSD microdosing on sustained attention

Article Title: LSD microdosing: Study indicates it makes women’s attention sharper, but no improvement in men

Article References: LSD microdosing: Study indicates it makes women’s attention sharper, but no improvement in men. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: LSD, microdosing, psychedelics, sustained attention, sex differences, cognition, placebo-controlled trial, University of Maastricht, ECNP, attention lapses, neuropsychopharmacology, personalised medicine