Cannabis Tablet Scores Correlated With Lane Control Without Predicting Its Change
A tablet-test factor correlated with lane-position variability at separate assessments, yet changes in the factors did not significantly predict changes in lane control. Cross-sectional correlation and detection of drug-related deterioration answer different questions.
Several outcomes were combined
The study analyzed 86 adults completing a tablet battery before and after cannabis use or a control rest period. Exploratory factor analysis condensed 18 measures into seven factors. Cannabis users consumed their own flower, so the absorbed THC dose was not identical across participants.
The driving subset was smaller
Complete simulator data were available for 83 participants. One factor showed significant correlations with lane-position variability at both the pre-use and post-use assessments. However, regression analyses accounting for baseline lane control did not find factor-score changes to be significant predictors of lane-control changes.
Why that distinction matters
A person with generally slower or less accurate performance might also have different lane control at either assessment. That relationship does not establish that the tablet measure detects the change caused by cannabis in the same person. A useful detection tool needs evidence matched to that intended purpose.
An exploratory analysis, not independent driving validation
The paper used the same research population as the driving study discussed in our related analysis, rather than providing an independent replication. Factor construction and evaluation in a relatively small sample require external validation. The study did not establish an individual pass/fail threshold, diagnostic sensitivity or prospective crash prediction. Its contribution is a method for exploring shared variation among tasks, with important limits on interpreting that variation as impairment.
Related analysis: the related daily-versus-occasional driving comparison.
Primary research
Smith SJ; Wrobel J; Brooks-Russell A; Kosnett MJ; Sammel MD. A Latent Variable Analysis of Psychomotor and Neurocognitive Performance After Acute Cannabis Smoking. Cannabis (Albuquerque, N.M.) (2023). DOI: 10.26828/cannabis/2023/000156.
