Tablet-based tests detected cognitive impairment after smoking cannabis | Research

The takeaway

A tablet-based neurocognitive test battery detected acute impairment from cannabis smoking, with occasional users showing larger deficits than daily users.

Impairment testing researchers, traffic safety policymakers, occupational health professionals, and anyone interested in cannabis and cognitive function.

Occasional users showed greater impairment than daily users after smoking

What the researchers found

Factor analysis identified a single latent construct underlying reaction time, decision making, working memory, and spatial-motor performance. Cannabis smoking produced measurable impairment on this construct, with occasional users more affected than daily users.

Why it matters

Developing reliable, portable tools for detecting cannabis impairment is important for roadside testing, workplace safety, and clinical assessment. Current field sobriety tests were designed for alcohol, not cannabis.

The numbers in context

Four cognitive domains tested: reaction time, decision making, working memory, and spatial-motor performance. Occasional users showed greater impairment than daily users after acute cannabis smoking.

How the study worked

Participants completed a tablet-based neurocognitive test before and after smoking cannabis (or a rest period for controls). Exploratory factor analysis reduced test dimensions, and regression models quantified impairment by user group.

What this study cannot tell us

Study conducted in a legal-use state, which may affect generalizability. Comparison between daily and occasional users confounds tolerance with other behavioral differences. No standardized cannabis dose. Ecological validity of tablet tests for real-world impairment is unestablished.

How to read the evidence

Observational study with a novel assessment tool. Reasonable design but limited by lack of dose standardization and unestablished real-world validity.

When this study was published

Published 2022.

The bigger picture

As cannabis legalization expands, the need for practical impairment detection tools grows. Unlike alcohol, there is no widely accepted cannabis equivalent of a breathalyzer. Tablet-based cognitive testing could fill that gap if validated at scale.

Questions still open

How does this test battery perform compared to standardized field sobriety tests? What threshold score should indicate impairment for practical applications?

Common questions

Why are occasional cannabis users more impaired than daily users?

Regular cannabis users develop tolerance, meaning their brains partially adapt to the presence of THC. Occasional users lack this adaptation, so the same amount of THC produces a larger cognitive effect. This does not mean daily users are unimpaired; their baseline performance may already be affected.

Could a tablet test replace a breathalyzer for cannabis?

Not yet. This study shows tablet-based tests can detect group-level impairment after cannabis use, but translating that to an individual-level pass/fail determination is much harder. Individual variation in cognitive ability, tolerance, and other factors make threshold-setting challenging.

Read the original research

A Latent Variable Analysis of Psychomotor and Neurocognitive Performance After Acute Cannabis Smoking.

Cannabis (Albuquerque, N.M.), 6(2), 123-132

View on PubMed ↗Publisher’s paper ↗

Citation

Smith, Shelby J; Wrobel, Julia; Brooks-Russell, Ashley; Kosnett, Michael J; Sammel, Mary D. (2023). A Latent Variable Analysis of Psychomotor and Neurocognitive Performance After Acute Cannabis Smoking.. Cannabis (Albuquerque, N.M.), 6(2), 123-132. https://doi.org/10.26828/cannabis/2023/000156