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The effect of cannabis use and gender on the visual steady state evoked potential.

Patrick D. Skosnik, Giri P Krishnan, Jenifer L Vohs, Brian F O'Donnell

Clinical Neurophysiology January 2006 DOI: 10.1016/j.clinph.2005.09.024 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational cohort Peer reviewed
Sample size 33
Population Current cannabis users and drug-naive controls
Measures SSVEP spectral power, phase-locking factor (PLF), N160 event-related potential
Topics Cannabis
Key findings Cannabis users showed reduced N160 amplitudes regardless of gender, and altered SSVEPs, with a gender-by-group interaction at 18 Hz and a positive correlation between age of onset and 18 Hz power. This suggests cannabis use affects visual processing and oscillatory properties in sensory cortical circuits.

Abstract

Cannabis use often induces subjective distortions of perception. However, little work has been done examining the electroencephalographic (EEG) correlates of early sensory processing in cannabis users. The present study therefore examined visual function in cannabis users as assessed via the steady state visual evoked potential. (SSVEP). SSVEPs were examined in current cannabis users (n = 17; 59% male; mean age = 23.2 (S.D. = 5.3)) and drug-naive controls (n = 16; 38% male; mean age = 21.3 (S.D. = 3.1)) to periodic photic stimulation presented at 18 and 25 Hz. The visual SSVEP was quantified via spectral power and the phase-locking factor (PLF) at each frequency of stimulation. The transient N160 event-related potential (ERP) was also evaluated at stimulus onset. The results showed that for both frequencies, female subjects in general displayed larger visual SSVEPs. A significant gender X group interaction also occurred at 18 Hz of stimulation, and age of onset of cannabis use positively correlated with 18 Hz spectral power values. Finally, the transient N160 component was shown to be reduced in cannabis users, regardless of gender. The present study was the first to demonstrate altered visual SSVEPs in cannabis users, and extends previous research demonstrating increased steady state responses in female subjects. While decreased SSVEPs provide initial evidence of altered oscillatory properties in primary visual circuits, reduction of the transient N160 component suggests disruption of later-stage visual processing in cannabis users. These data provide evidence of cannabinoid modulation of sensory/perceptual function in the visual system, and indicates that cannabis use may affect the oscillatory properties of sensory cortical circuits.

Comparable studies

Other observational and cohort studies on cannabis, most cited first.

Study Year Design Participants
High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population 2009 Case-control study n = 454
Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population 2013 Observational study
Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people 2000 Observational
Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline 2011 Observational cohort n = 1,923
Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... 2005 Observational cohort n = 535

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