Sex, drugs, and cognition: effects of marijuana

Abstract

Despite the knowledge that many drugs affect men and women differently, few studies exploring the effects of marijuana use on cognition have included women. Findings from both animal and human studies suggest marijuana may have more marked effects in women. This study examined sex differences in the acute effects of marijuana on cognition in 70 (n=35 male, 35 female) occasional users of marijuana. Tasks were chosen to tap a wide variety of cognitive domains affected by sex and/or marijuana including attention, cognitive flexibility, time estimation, and visuospatial processing. As expected, acute marijuana use impaired performance on selective and divided attention, time estimation, and cognitive flexibility. While there did not appear to be sex differences in marijuana's effects on cognition, women requested to discontinue the smoking session more often than men, likely leading to an underestimation of differences. Further study of psychological differences in marijuana's effects on men and women following both acute and residual effects of marijuana is warranted.

Figure 1

Subjective ratings of “highness” by sex at each time point. Participants receiving the active marijuana dose rating themselves significantly “higher” than those receiving placebo at each time point after smoking. Women rated themselves as significantly “higher” than men immediately after smoking and prior to cognitive testing.

Figure 2

Heart rate for each sex and dose at each time point. After smoking, active marijuana increased heart rate significantly more than placebo. No sex differences were observed.

Figure 3

Stanford Sleepiness Scale scores for each sex and dose at each time point. Active marijuana increased sleepiness compared to placebo in participants prior to and post-cognitive testing, and at discharge. Women exhibited more sleepiness than men prior to cognitive testing, but at no other time points.

Figure 4

Task switching scores for each sex and dose. Active marijuana increased reaction times for the cued condition whether or not a switch in task was needed and women responded more slowly than men to the cued condition. No differences were identified in random trials and no sex by drug interactions were observed.