In one of the few studies designed to examine subjective behavioral effects and impulsivity associated with marijuana use, McDonald et al. (2003) examined occasional users of marijuana after taking one of two acute doses (7.5,15 mg) of oral THC or a placebo. Subjects were administered clinical rating scales and tasks designed to measure impulsivity. The authors reported that THC administration increased subjective ratings of euphoria, dysphoria, somatic effects and sedation; decreases in intellectual efficiency and energy were also noted. Significantly increased scores on anxiety, fatigue, anger and confusion, as measured by the Profile of Mood States (POMS) (McNair et al., 1971) were also demonstrated following THC administration, which were noted to be dose dependent. Behavioral results from this study indicate that THC administration affected two of the four measures of impulsivity, increasing impulsive responses to the Stop task and altering patterns of response on a time estimation task, however, no significant effect was noted on either the Go/No Go task or the Delay Discount task. The authors interpret the findings to suggest that multiple processes underlie impulsivity, only some of
