Objective: Evidence from recent research shows greater impairment on neurocognitive functioning tasks in adolescent-onset versus adult-onset cannabis users. However, most previous research failed to examine the effect of participants' motivation and effort on test performance. The present study examines the relationship between age of onset of cannabis use and neurocognitive performance, when effort is enhanced via a motivational statement. Method: Prior to administration of a neuropsychological battery, 28 chronic cannabis users received a motivational statement (onset ≥18 years, n = 8) and 34 chronic cannabis received a neutral statement (onset ≥18 years, n = 11). Results: An independent samples t-test was used to examine the performance of the two conditions. In the neutral condition, users with onset before age 18 (n = 23) performed worse on the California Verbal Learning Test-Second Edition (CVLT-II), Trial 5 (p = 0.037); Rey Complex Figure Test, Copy (p = 0.017), Immediate Recall (p = 0.015), with performance on Trail Making Part A Errors and CVLT-II Total Repetitions nearing significance (p = 0.051). However, in the motivational condition, those with onset before age 18 (n = 20) performed worse on only one test (CVLT-II Total Intrusions, p = 0.003) and better on other CVLT-II subtests than participants with onset after age 18 (n = 8). Conclusion(s): These findings suggest the motivational statement resulted in better performance, particularly for users who initiated use prior to age 18. Thus, previous research identifying a negative effect of earlier use onset may not account for the enhanced performance demonstrated when users are given an inherently motivating statement. Implications will be discussed.
PROFESSIONAL ISSUES: EFFORT AND MOTIVATION