Detection of Δ9-Tetrahydrocannabinol Impairment Using Resting-State Functional Near-Infrared Spectroscopy: A Randomized Clinical Trial.
JAMA network open January 2, 2026 Moshe Berchansky, A Eden Evins, Bryn Evohr et al. 1 citation
A brain-imaging technique called resting-state functional near-infrared spectroscopy (fNIRS) detected THC-induced impairment more accurately and with far fewer false positives than standard behavioral field sobriety tests (FSTs). In a double-blind, randomized crossover trial, 183 regular cannabis users (average age 25, half female) received either a single oral dose of synthetic THC or a placebo. fNIRS scans of the prefrontal cortex, taken at rest and during a working-memory task, were used to train machine-learning models to identify clinically determined intoxication. The fNIRS classifier achieved 90% accuracy and a 5% false-positive rate, compared with 69% accuracy and a 34% false-positive rate for FSTs. The findings suggest that resting-state fNIRS may provide a more reliable, objective method for detecting cannabis-related driving impairment.