The American Journal of Psychiatry

American Journal of Psychiatry 163:1798-1805, October 2006
doi: 10.1176/appi.ajp.163.10.1798
© 2006 American Psychiatric Association

Psychophysiological Evidence of Altered Neural Synchronization
in Cannabis Use: Relationship to Schizotypy

Patrick D. Skosnik, Ph.D., Giri P. Krishnan, B.S., Erin E. Aydt, B.S., Heidi A. Kuhlenshmidt, B.S. and Brian F. O’Donnell, Ph.D.


OBJECTIVE: Cannabis use may produce neurophysiological disturbances similar to those observed in schizophrenia, particularly in relation to altered neural synchronization. Therefore, the current experiment examined the effect of cannabis use on EEG neural synchronization using the auditory steady-state evoked potential. METHOD: Auditory steady-state evoked potentials were assessed using varying rates of stimulation (auditory click-trains of 20, 30, 40 Hz) in current cannabis users (N=17) and drug-naive comparison subjects (N=16). EEG spectral power and signal-to-noise ratio at each stimulation frequency were compared between groups. RESULTS: Cannabis users showed decreased EEG power and signal-to-noise ratio at the stimulation frequency of 20 Hz. In addition, current cannabis users demonstrated increased schizotypal personality characteristics as assessed with the Schizotypal Personality Questionnaire, which positively correlated with total years of cannabis use. Finally, within the cannabis group, 20-Hz power values were negatively correlated with Schizotypal Personality Questionnaire scores. CONCLUSIONS: These data provide evidence for neural synchronization and early-stage sensory processing deficits in cannabis use. This finding, along with the observed increased rates of schizotypy in cannabis users, adds support for a cannabinoid link to schizophrenia spectrum disorders.