Sensory gating, cannabis use and the risk of psychosis

Presentation First Author: 
Toby Winton-Brown

Sensorimotor gating, measured as the modification of eye blink startle reflexes to acoustic stimuli by quieter preceding stimuli, is altered in those with psychosis their relatives and those at high clinical risk (UHR) for psychosis. Alterations have also been shown in cannabis users, albeit to a lesser extent, and cannabis is a known risk factor for the onset of psychosis in clinically and genetically susceptible individuals. We examined the interaction between clinical risk for psychosis and cannabis use on sensory gating, at pre-attentive (Prepulse Inhibition, PPI) and attentive (Prepulse Facilitation, PPF) stages. We tested PPI and PPF using a standard paradigm in participants at high clinical risk for psychosis and a matched control group. Both groups included a proportion of subjects who had recently cannabis, as confirmed by urinary drug screening on the day of testing. We found that ARMS participants showed reduced PPF and PPI relative to controls, the latter driven by a group by cannabis use interaction, with recent use reducing PPI in ARMS participants but not in controls. When the analysis was limited to UDS-negative participants there was significantly reduced PPF in ARMS subjects relative to controls, but no differences in PPI. Cannabis use in clinical high risk individuals may increase risk of psychosis in part through worsening pre-attentive sensory filtering, while attentive sensory processing is altered in UHR individuals regardless of recent cannabis use. This develops our understanding of cognitive mechanisms leading to the experience of aberrant perceptual phenomena and the development of psychotic symptoms.

Conference Name: 
Presentation Date: 
January, 2015
Additional Authors: 
Veena Kumari - Windler Florian - Moscoso Ana - Stone James - Kapur Shitij - McGuire Philip
See other presentations in this session: