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Reduced P50 auditory gating response in psychiatrically normal chronic marihuana users: a pilot study
G Patrick1, J J Straumanis, F A Struve
1Department of Psychiatry, Louisiana State University School of Medicine, Shreveport 71130-3932, USA.
Biological Psychiatry
|June 1, 1999
Summary
Chronic cannabis (THC) use is linked to reduced P50 sensory gating, indicating impaired brain signal processing. This neurophysiological change may be a long-term effect of cumulative THC exposure in healthy individuals.
Area of Science:
- Neuroscience
- Psychopharmacology
Background:
- Previous studies on cannabis (THC) neurophysiology often lacked controls for confounding factors like psychiatric conditions or polydrug use.
- This study focused on rigorously screened, medically and psychiatrically healthy individuals with chronic THC exposure, excluding other substance use.
Purpose of the Study:
- To investigate the neurophysiological effects of chronic tetrahydrocannabinol (THC) exposure on sensory gating in humans.
- To determine if THC use alters the P50 auditory evoked potential, a measure of sensory gating.
Main Methods:
- P50 paired auditory recovery tests were administered to 19 chronic THC users and 14 control subjects after thorough medical, psychiatric, and drug screening.
- Sensory gating was measured by comparing P50 amplitudes elicited by paired auditory clicks, with a higher ratio indicating reduced suppression.
Main Results:
- Chronic THC users exhibited significantly higher P50 sensory gating ratios, signifying reduced suppression of the second click's response compared to controls.
- No significant correlation was found between sensory gating ratios and the duration or frequency of THC use among users.
Conclusions:
- Reduced P50 suppression observed in the sensory gating paradigm may represent a neurophysiological consequence of long-term, cumulative exposure to THC.
- This finding suggests a potential central nervous system (CNS) sequela associated with chronic cannabis use.