Cannabis and driving: study probes how chronic use blurs vision of moving objects

NCT ID NCT01793961

Completed Knowledge-focused Sponsor: University Hospital, Strasbourg, France Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study investigates whether chronic cannabis use impairs contrast sensitivity — the ability to see objects clearly against their background, especially when they are moving. Researchers will compare three groups: cannabis addicts, tobacco-only smokers, and non-smokers. Participants will take vision tests with static and moving patterns to see if cannabis users have worse contrast detection, which could affect driving safety.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

What this could lead to: If cannabis impairs contrast sensitivity, this could help explain why users are at higher risk for car crashes and inform driving safety guidelines.
What could go wrong: This is a small observational study comparing groups, not a treatment trial. It cannot prove cause and effect, and results may not apply to all cannabis users.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

cannabis dependence

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

CANNABIS DEPENDENCE

Contacts and locations

Locations

Study site

Strasbourg, Bas-Rhin, 67300, France

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Other studies related to the condition(s) this trial covers.