Study: Frequent Cannabis Consumers Exhibit Short-Term Changes in Psychomotor Performance Following Marijuana Ingestion

Boulder, CO: Frequent cannabis consumers exhibit changes in psychomotor performance in the 60-minute period following their use of either marijuana flowers or concentrates, according to data published in the journal Cannabis and Cannabinoid Research.

A team of investigators affiliated with the University of Colorado, the University of Washington, and Tufts University in Boston assessed the influence of cannabis on psychomotor performance as measured by the DRUID mobile app. Prior studies have demonstrated DRUID to be more sensitive to marijuana-induced changes in performance than Field Sobriety Tests. Participants in the study were frequent users of cannabis and were instructed to inhale ad libitum high-potency cannabis flowers or concentrates. Subjects’ performance after inhalation was measured against their individual baseline performance.

Researchers reported that subjects’ changes in performance “peaked shortly after acute use and decreased over the next hour” – a finding that is consistent with prior research. Participants exhibited similar degrees of impairment regardless of whether they consumed flowers or concentrates. Changes in performance were most pronounced with respect to balance, reaction time, and in subjects’ abilities to properly process multiple pieces of information at one time (divided attention).

Authors concluded, “This study demonstrated that regular cannabis users show a decrease in performance on the DRUID app immediately after cannabis ingestion but appear to ‘recover’ almost back to baseline levels 1-hour post-use.” They added: “At present, there is a great need for a well-supported brief and mobile method for determining acute cannabis-related impairment, but no such tool exists. Considerable further validation and development are needed to determine whether a testing battery like DRUID may have individual or other applications as a driving impairment test.”

NORML has long acknowledged that acute cannabis intoxication can influence driving performance, particularly with respect to decreases in driving speed and changes in lateral control, and has opined that anyone inhaling cannabis “should refrain from driving for a period of several hours.” More pronounced changes in driving performance are typically present when cannabis is consumed in combination with alcohol.

NORML has also expressed longstanding opposition to the imposition of either per se or zero-tolerant per se traffic safety limits for THC or its metabolites because their presence is not consistently associated with impairment of psychomotor performance. NORML has opined in favor of the use of performance testing technology as a more reliable indicator of cannabis-induced impairment.

Full text of the study, “Effects of high-potency cannabis on psychomotor performance in frequent cannabis users,” appears in Cannabis and Cannabinoid Research. Additional information is available from the NORML fact sheet, “Marijuana and Psychomotor Performance.”