A systematic review of 29 studies found limited evidence that sex influences the acute cognitive effects of cannabis or THC in humans. Only 6 of 29 articles (20.7%), representing 8 of 216 cognitive outcomes (3.7%), reported sex differences. All six studies found greater cognitive impairment in female participants for at least one measure; one study also found greater effects in male participants, and one found divergent effects between sexes. No consistent patterns emerged by cognitive domain, route of administration, or dosing paradigm. Methodological heterogeneity across studies prevents firm conclusions, and future research should examine hormonal modulation of cannabinoid effects.
A genetic variant of ABCB1, which encodes a protein that pumps substances out of cells, may influence how the body processes THC from smoked cannabis. In 48 young adults who used cannabis 1–4 days per week, those carrying a C allele at the rs2235048 polymorphism had higher blood levels of THC metabolites after smoking a single cannabis cigarette than those with the TT genotype. C-allele carriers also reported using cannabis more frequently each week and greater drug liking. No other subjective drug effects differed between groups. The findings are preliminary and suggest that ABCB1 could affect cannabis-related traits and risk for cannabis use disorder, but larger studies are needed.
Taking a low-dose cannabis edible (average 7.3 mg of THC) leads to measurable decreases in verbal learning and memory, specifically on two measures of a free recall task, 150 minutes after ingestion. No effects were found on visual attention or executive function as measured by the useful field of view and trail making tests. Subjective feelings of intoxication increased, but blood THC levels did not correlate with any cognitive performance changes. The results suggest that people who use relatively low doses of cannabis edibles may experience some cognitive decrements while feeling intoxicated.
Smoked cannabis containing varying levels of Δ9-THC produced potency-dependent impairments in simulated driving. In a randomized, double-blind, placebo-controlled trial, adults who regularly used cannabis and held valid driver's licenses completed driving tasks after smoking placebo or cannabis with low (6.25%/47 mg), medium (12.5%/94 mg), or high (22%/165 mg) Δ9-THC. Mean speed did not differ across conditions, but maximum speed increased under medium and high potencies versus placebo. Standard deviation of lateral position (SDLP) was higher across all potencies, and reaction time (RT) was longer under medium and high potencies. Both SDLP and RT correlated positively with blood Δ9-THC concentrations. Participants reported poorer driving performance and reduced willingness to drive at higher potencies.