A Four-Day Session Washout Was Not Four Days of Cannabis Abstinence
The interval between experimental sessions should not be mistaken for verified cannabis abstinence. In a heavy-user study, participants could continue their usual cannabis routine despite a minimum four-day interval between treatments.
The instructions defined the exposure history
Ramaekers and colleagues allowed usual cannabis smoking during the study period. Participants were screened on test days, and the experimental alcohol/THC treatment required a positive THC result with negative results for other screened drugs and alcohol.
The session baseline was not drug-free
The paper reports measurable serum THC before the study cigarette. That baseline described participants under the study’s actual conditions; it was not a measurement after an established four-day cannabis-free period. Serum results also should not be relabeled as whole-blood concentrations.
Washout can refer to scheduled treatment
Spacing experimental sessions helps separate assigned treatments, but does not by itself define what participants consumed between visits. The protocol’s instructions and specimen results are needed to understand that distinction. These findings do not establish the exact contribution of each prior use episode to baseline concentrations or performance. They do show why the words washout and abstinence cannot be exchanged when describing a study’s starting condition or interpreting a tolerance comparison.
Related: Interpreting cannabinoid tolerance evidence.
Research cited
Ramaekers JG and colleagues. Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users (2011).
