Woman tend to be more sensitive to the psychomotor-related behavioral and subjective effects of methamphetamine than men, according to a new study published in the journal Psychopharmacology. The findings could help explain why women tend to transition from recreational methamphetamine use to dependence more quickly.
“We were interested in exploring individual differences in acute or early drug responses, prior to the development of a drug use disorder,” explained study author Leah Mayo, a postdoctoral research fellow at Linköping University in Sweden.
“While many people will try drugs throughout their life, only a minority (albeit, a significant minority) will develop a substance use disorder. Doing studies like these in healthy, non-dependent humans allows us to understand how people vary in response to a drug and how that variation may make them more vulnerable, or resilient, to the development of a drug use disorder.”
“In particular, clinical and epidemiological reports suggest that women are more vulnerable to developing a methamphetamine use disorder. However, it is unclear what contributes to these different drug use trajectories. Here, we asked whether gender differences in response to methamphetamine exist early on, prior to the development of problematic use.”
In the study, 44 men and 29 women completed four sessions in which they received either placebo or methamphetamine (20 mg) under double-blind conditions.
About 30 minutes into each session, the participants completed a monetary incentive delay in which they had to respond quickly to a target in order to win or avoid losing money. The participants also completed assessments of mood and drug effects, and the researchers monitored their blood pressure and heart rate.
“We find that women are more sensitive to psychomotor-related effects of methamphetamine than men. In particular, women report feeling more ‘vigor’ and less ‘fatigue’ after taking the drug. Behaviorally, they also show faster reaction times in a reward-processing task,” Mayo told PsyPost.
“Together, we propose that this heightened sensitivity to the behavioral and subjective effects of methamphetamine in women may render them more likely to use the drug again, and perhaps escalate use over time. This supports clinical data showing that female methamphetamine users transition more quickly from recreational use to dependence than their male counterparts.”
The findings provide some new insights into the effects of methamphetamine, but more research is needed to clarify the relationship between these effects and addiction.
“We have shown that women are more sensitive to some of the effects of methamphetamine and we hypothesize that this sensitivity may render them more vulnerable to develop problematic use patterns. However, we still don’t know if this is true; that is, are those most sensitive to these drug effects actually the ones who are more vulnerable to developing a use disorder?” Mayo explained.
“We also don’t know how these effects change over time. More specifically, how do the behavioral and subjective responses to methamphetamine change as drug use escalates? There are still many clinical questions to be answered, but we hope that this study provides a starting point for understanding gender-based differences in methamphetamine effects and consumption.”
“One interesting observation is that the differences we report between men and women seem to be specific to methamphetamine. Work from others suggest that similar gender differences are not evident in response the closely related drug, D-amphetamine,” Mayo added.
“Strikingly, very similar effects have been reported in preclinical animal models: psychomotor effects of methamphetamine, but not D-amphetamine, differ between male and female rodents. The fact that this sex-based difference also exists in preclinical animal models opens up the avenue for gaining a more mechanistic understanding of the neurobiological underpinnings of these behaviors.”
The study, “Gender differences in the behavioral and subjective effects of methamphetamine in healthy humans“, was authored by Leah M. Mayo, Elisabeth Paul, Jessica DeArcangelis, Kathryne Van Hedger, and Harriet de Wit.