LSD microdosing shows sex-specific effects on attention in pilot study

Researchers at the University of Maastricht have found that microdosed LSD—tiny amounts of the drug taken well below the threshold of a full psychedelic experience—appears to sharpen sustained attention in women but produces no measurable benefit for men. The discovery, presented at the European College of Neuropsychopharmacology congress in Munich, arrives as a reminder that the human body does not respond uniformly to any substance, and that claims about psychedelic microdosing deserve careful scientific scrutiny.

Microdosing has entered popular conversation as a potential cognitive enhancer. People report taking small doses of LSD in hopes of improving focus, concentration, productivity, or mood, and some describe using it to manage attention problems. Yet controlled studies have yielded mixed results, leaving the actual effects largely unknown. The Maastricht team set out to test these claims in a rigorous way: a randomized, double-blind study in which neither participants nor researchers knew who received the drug and who received placebo until the work was complete.

Forty-eight healthy volunteers, with an average age of 36.9 years and including 24 women, participated in the trial. Over two weeks, participants received either placebo or four separate doses of LSD, each containing 15 micrograms—well below the 60 microgram threshold at which typical psychedelic effects emerge. The researchers assessed three dimensions of mental performance: sustained attention, information processing, and working memory. Participants completed cognitive tests at baseline, after the first dose, after the fourth dose, and again at follow-up.

The most striking finding emerged from the sustained attention test, in which participants watched a screen and pressed a button as quickly as possible when a signal appeared. Women who received placebo showed slower reaction times and more frequent attention lapses than men in the same condition. When those same women received the microdosed LSD, their performance shifted noticeably. Their reaction times improved by roughly 8 percent—from 335 milliseconds to 308 milliseconds—and they experienced far fewer lapses in focus: an average of 2.3 lapses compared to 4.7 under placebo. This pattern held after the first dose, persisted through repeated dosing, and remained visible at follow-up. Men given the microdoses showed no comparable improvement.

Iva Totomanova, the lead researcher, emphasized that the findings point to something more nuanced than a simple claim that LSD sharpens cognition or that women are inherently more responsive to the drug. "Effects may depend on the person, the cognitive task being measured and the circumstances of use," she said. The results on information processing and working memory were less clear-cut, which may explain why sex-related differences were missed in earlier studies. The researchers note that this work is a re-analysis of an existing dataset, meaning the findings remain preliminary and require confirmation in a study specifically designed to examine sex differences—one that would account for hormone levels, menstrual phase, and contraceptive use.

Totomanova acknowledged the limitations plainly: the sample was small, the variables numerous, and the results need replication in a larger population. Yet she framed the work as part of a broader shift in how researchers think about psychedelics. "We are beginning to see that people respond to psychedelics in different ways. With psychedelic pharmaceuticals, it looks like personalized medicine is important." The implication is that if psychedelics move toward therapeutic use, clinicians may need to account for individual variation—not just in who responds, but in how and why they respond.

Mikkel Højlund, a researcher at the University of Southern Denmark who was not involved in the study, noted that rigorous testing of microdosing claims matters precisely because the practice has attracted media attention and popular interest. A double-blind, placebo-controlled design strengthens confidence in the findings, he said, though he agreed with the authors that larger, more targeted studies are necessary. The question now is whether the pattern holds when researchers deliberately measure the biological factors that might explain why women and men diverge in their response to a 15-microgram dose.