A Cannabis Sex-Difference Finding Changed When Baseline Performance Was Accounted For

In one controlled cannabis study, a sex difference in impairment classification appeared with raw task scores but was not significant after accounting for baseline performance. The finding shows why the definition of the outcome matters before attributing a difference to THC susceptibility.

The comparison involved a small human sample

Spindle and colleagues studied 20 infrequent cannabis users, including 10 men and 10 women, across six double-blind sessions involving oral or vaporized cannabis and placebo conditions. Outcomes included the DRUID task, other computerized measures and field sobriety tests.

At the high vaporized dose, 20 mg THC, raw DRUID data classified seven women and two men as impaired. That comparison was statistically significant. The corresponding classification difference was not significant when change from baseline was used.

Raw status and change answer different questions

A raw-score rule asks whether a person crosses a specified performance boundary. A baseline-adjusted comparison asks how performance changed relative to that person’s earlier measurement. A pre-existing difference can influence the first question without producing the same result on the second.

This does not prove that the raw classifications were false or that baseline adjustment is always preferable. It means the two analyses cannot be quoted interchangeably as evidence of a biological sex effect.

Preserve the null findings too

The study did not find that classification difference across every experimental condition, and field-test classifications did not show the same sex pattern. A single dose-and-task result should therefore remain tied to that condition.

For an individual assessment, review the scoring rule, baseline measurements and route of administration. Neither sex alone nor a group finding from this small sample supplies a personal impairment determination.

Related: What a within-person cannabis trial can and cannot generalize.

Research cited

Spindle TR; et al.; Journal of Psychopharmacology; 2021. Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis.