Objective:

This study investigated the impact of high-potency acute cannabis intoxication on cognitive functioning in habitual cannabis users.

Background:

Traditional research protocols require federally approved cannabis cigarettes containing ~ 1-10% tetrahydrocannabinol (THC), not reflecting real-world potency of products containing up to 30% THC. Thus, prior studies may underestimate cognitive effects of naturalistic cannabis use. This study builds on prior research examining acute cannabis intoxication on prospective memory (PM), which refers to establishing, maintaining, and completing future behavioral goals. Computer-based PM tasks are dependent on memory and attention processes, which can be impaired by THC.

Design/Methods:

We used a mixed-methods observational design to investigate naturalistic cannabis use. Eligible participants purchased cannabis cigarettes with ≥ 20% THC. One hour after use, participants completed a computer-based PM task making two-alternative forced-choice lexical decisions (word vs. nonword). Participants were instructed to press a special key when seeing a word/nonword containing the syllable TOR. Key dependent measures were: proportion of PM cues eliciting the special keypress, PM cue trial response time (RT), and lexical decision accuracy and RTs on non-cue trials. Participants' performance was compared with controls.

Results:

The cannabis group responded to fewer PM cues than controls [one-tailed t(156) = 1.91, p = 0.03, d = 0.31]. They exhibited faster RTs on PM cue trials [t(131) = 3.52, p < .001, d = 0.62]. For ongoing task performance, the cannabis group was less accurate [t(131) = 3.84, p < .001, d = 0.611] and quicker [t(159) = 3.59, p < .001, d = 0.57] on the lexical decision task.

Conclusions:

We replicate prior work on cannabis intoxication. The cannabis group displayed faster RTs and decreased accuracy across both PM and ongoing task trials, indicating a potential tradeoff between speed and accuracy. This tradeoff suggests participants did not adequately assess task demands, resulting in reduced PM cue detection.