Does the effect of microdosing psychoactive substances vary by sex?
According to researchers at Maastricht University, women who took a low dose of LSD performed better on sustained attention and reaction speed tests compared to the placebo group, whereas no such improvement was observed in men.
Study Design and Dosing
Researchers analyzed the impact of microdosing LSD through a re-analysis of data from a previously conducted study. In the original trial, scientists investigated the effects of repeated administration of 15 micrograms of LSD, whereas the new analysis focused on potential differences in cognitive outcomes between men and women.
This amount (15 mcg) is considered a low, micro-dose and is substantially lower than the dose that typically induces a full psychedelic experience.
The study included 48 healthy volunteers (24 women and 24 men, mean age — 36.9 years). Participants were randomly divided into two groups: one group received LSD, and the other received a placebo. Over the course of two weeks, participants were administered the drug or placebo four times. The trial was conducted using a double-blind method: neither the participants nor the researchers knew who was in which group.
Scientists evaluated the participants’ cognitive functions across three main domains: working memory, information processing speed, and sustained attention. The latter was measured using the Continuous Performance Test (CPT), during which participants had to maintain focus over a period of time and respond quickly to visual stimuli.
Sustained Attention and Reaction
In the 10-minute Continuous Performance Test (CPT), which evaluated the ability to maintain continuous concentration, two main improvements were identified among women in the LSD group:
Reaction time: In women who took a micro dose of LSD, the mean reaction time to visual stimuli decreased from 335 to 308 milliseconds, representing approximately an 8% improvement.
Lapses of attention: Over the 10-minute test, the average number of attention lapses in women receiving the placebo was 4.7, while in women taking LSD it was 2.3. Thus, this rate was reduced by more than half in the LSD group.
However, despite receiving an identical dose, no similar statistically significant improvement in reaction time or sustained attention was recorded in men.
In tests measuring information processing and working memory, no statistically significant improvements were observed in the LSD group compared to the placebo group — in neither women nor men.
The study results were presented by the scientists at the Congress of the European College of Neuropsychopharmacology (ECNP).
Scientific Limitations and Future Perspectives
As the researchers note, the results obtained do not prove that low doses of LSD generally improve cognitive functions or that women are more sensitive to this substance than men. The identified difference specifically relates to the Continuous Performance Test. Since the original aim of the study was not to explore sex differences, large-scale, prospective studies designed in advance are necessary to determine the exact mechanisms behind the effect.
Future research must also account for physiological factors such as: ovarian hormone fluctuations (estrogen, progesterone), phases of the menstrual cycle, and the use of oral contraceptives.
According to the study’s author, Iva Totomanova, the results indicate that accounting for individual differences is crucial in neuropsychopharmacology and that a one-size-fits-all approach may not be equally effective for everyone. As she explains, the effect may depend on the individual, the cognitive task being evaluated, and the circumstances of use. “A more accurate question would be: on whom does microdosing work, and under what circumstances?” notes the researcher.
