Different THC Regimens Limited a Comparison Between Two Primate Behavioral Tests
Different tolerance findings across two tasks cannot be attributed solely to the tasks when treatment regimens also differ. A primate study explicitly identified this limit on its cross-procedure comparison.
The procedures used different exposure histories
McMahon studied rate-decreasing effects during a repeated twice-daily THC regimen and drug-discrimination effects after a separate once-daily regimen lasting up to six days. The groups also differed in prior experimental experience.
The paper retained the design limitation
The author noted that different treatment parameters precluded assessing whether tolerance developed equally for the two behavioral measures. Differences in dose schedule and duration were not experimentally separated from differences in what the tasks measured.
Within-procedure findings still remain useful
This limitation does not erase the observed dose–response shifts or the cannabinoid comparisons within each procedure. It narrows the explanation for a difference between procedures. An experiment holding exposure constant while comparing outcomes would address the task-specific question more directly. The study therefore supports describing the regimens alongside each result, rather than presenting their contrast as proof that one function is intrinsically more resistant to tolerance. Neither task was a human impairment assessment.
Related: Interpreting cannabinoid tolerance evidence.
Research cited
Lance R. McMahon. Chronic Δ9-tetrahydrocannabinol treatment in rhesus monkeys: differential tolerance and cross-tolerance among cannabinoids (2011).
