In 910 university students, cannabis use predicted higher psychosis-like traits, and this relationship was partly explained by aberrant salience, a tendency to assign unusual importance to ordinary stimuli.
Psychosis researchers, cognitive neuroscientists, and clinicians assessing cannabis-related psychotic experiences.
Aberrant salience mediated the cannabis-schizotypy link for 5 key traits
What the researchers found
Among 910 students, frequent cannabis use predicted higher scores on positive and disorganized schizotypy subscales. Mediation analysis showed that aberrant salience (abnormal importance assignment) explained the relationship between cannabis use and specific traits including ideas of reference, odd beliefs, unusual perceptual experiences, and odd speech.
Why it matters
The dopamine hypothesis of psychosis centers on aberrant salience. This study provides the first evidence in a non-clinical population that cannabis may promote psychosis-like experiences specifically through disrupting how the brain decides what is important.
The numbers in context
910 students; frequent cannabis use predicted positive and disorganized schizotypy; aberrant salience mediated the relationship for ideas of reference, odd beliefs, unusual perceptions, and odd speech.
How the study worked
Cross-sectional survey of 910 university students using validated questionnaires for cannabis experience, schizotypal personality traits, psychic experiences, and aberrant salience. Mediation analysis tested whether salience dysfunction explained cannabis-schizotypy links.
What this study cannot tell us
Cross-sectional (cannot establish directionality); self-report measures; university sample may not generalize; schizotypy is not the same as clinical psychosis; cannot distinguish cause from predisposition.
How to read the evidence
Moderate: large non-clinical sample with mediation analysis, but cross-sectional and self-report.
When this study was published
Published 2020.
The bigger picture
This offers a cognitive mechanism linking cannabis to psychosis: cannabis does not just increase psychotic symptoms generally, but may specifically disrupt the brain filter that normally prevents us from over-interpreting random events as meaningful.
Questions still open
- Does cannabis acutely induce aberrant salience, or does pre-existing salience dysfunction drive cannabis use? Would CBD counteract THC-induced aberrant salience?
Common questions
What is aberrant salience?
Does cannabis cause psychosis-like thinking?
Read the original research
Does cannabis use predict psychometric schizotypy via aberrant salience?
Schizophrenia research, 220, 194-200
Citation
O'Tuathaigh, Colm M P; Dawes, Christopher; Bickerdike, Andrea; Duggan, Eileen; O'Neill, Cian; Waddington, John L; Moran, Paula M. (2020). Does cannabis use predict psychometric schizotypy via aberrant salience?. Schizophrenia research, 220, 194-200. https://doi.org/10.1016/j.schres.2020.03.021
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