Can EEG brain waves detect cannabis intoxication?

Cannabis intoxication was associated with decreased theta band power (3-5 Hz) during resting state, reduced P400 and late positive potential amplitudes during attention and memory tasks, elevated frontal coherence, and diminished anterior-posterior coherence in the theta band. These changes were consistent and distinguishable from the placebo condition.

Within-subject counterbalanced design with 12 healthy recreational cannabis users. EEG acquired using ABM STAT X24 headset during a 1-hour testbed of resting state, attention, and memory tasks. Spectral densities computed for resting state; event-related potentials obtained for cognitive tasks.

Unlike blood THC levels, which correlate poorly with actual impairment, EEG measures reflect real-time brain function. If validated in larger studies, EEG biomarkers could provide a more accurate and practical method for detecting cannabis intoxication, particularly for driving safety applications.

The search for reliable cannabis intoxication biomarkers is driven by the inadequacy of current methods (blood THC, oral fluid, urine) which detect use but not impairment. EEG offers a direct window into brain function that could bridge this gap, though significant validation work remains.

Very small sample (12 participants). Healthy recreational users may not represent the broader population. Single session design. Practical challenges of administering EEG in field settings (roadside) remain unresolved.