| Authors: Mastropietro KF, Rattigan JA, Sur M, Umlauf A, Grelotti DJ, Grant I, Fitzgerald RL, Marcotte TD |
| Abstract:Objective:
Time production (TP) and time estimation (TE) abilities are critical for everyday functioning, especially driving. TP involves proactively generating time intervals of predetermined duration (also used in field sobriety tests; FSTs) while TE involves retroactively judging the duration of elapsed time intervals. Although cannabis users often report experiencing that time moves slower, few studies have explored whether cannabis intoxication alters both TP and TE. Such studies were limited by small sample sizes, administration methods not reflecting real-world consumption, and inability to extend findings to activities of daily living. One study found that infrequent cannabis users (one month of abstinence) overestimated and underproduced time intervals following intravenous THC doses (Sewell et al., 2013). Older studies found similar results in young adult men after administration of oral THC (Bech et al., 1973; Tinkleberg et al., 1972). The current study examined whether acute use of smoked cannabis produced distortions in TP and TE, with extension to subsequent driving simulator performance.
Participants and Methods:
As part of a placebo-controlled clinical trial (Marcotte et al., 2022), 191 healthy adult cannabis users (using >4 times in the last 30 days) abstaining from use for >48 hours completed a driving simulation 30min post-smoking, immediately followed by TP and TE tasks. TP was measured during a law enforcement-administered FST where participants noted when they believed a 30-second interval passed, with scores between 25-35 seconds considered passing. TE was measured during a computerized task where participants counted the number of "M's" appearing onscreen (minimizing subvocal counting) across three trials lasting 19, 33, and 48 seconds, and then estimated each trial’s duration. The main driving outcome was the Composite Drive Score (CDS), a global measure of driving performance comprising variables such as swerving and car-following.
Results:
On the TP task, the cannabis group reported briefer intervals (underproduced) relative to placebo (mean 32 vs 36 seconds; p=.003) and were closer to 30 seconds. While both groups produced intervals below and within the FST’s 25-35-second target range (ps>.11), a larger proportion of the placebo group produced intervals >35 seconds relative to the cannabis group (45% vs 24%; p=.005). Within the cannabis group, reporting longer intervals (approaching placebo performance) was associated with better CDS (p=.048), but TP performance did not differentiate participants rated impaired/unimpaired on the driving simulation (ps>.2). On the TE task, the cannabis group estimated more time elapsed (overestimated) relative to placebo for the 48-second interval (mean 41 vs 37 seconds; p=.04), but not the 19- and 33-second intervals (ps>.19). Performance on the TE task was not associated with CDS, nor impairment on the driving simulation (ps>.2).
Conclusions:
The current study confirmed cannabis intoxication yields internal clock acceleration characterized by underproducing and overestimating time intervals relative to placebo. Findings were extended to driving simulator performance, and while less internal clock acceleration on the TP task was associated with better driving, overall TP and TE performances were not predictive of driving impairment ratings. Future studies may benefit from assessing more granular aspects of driving requiring intact temporal processing (e.g., crash avoidance). |