Cannabis use was not linked to changes in a learning task tied to psychosis, but was linked to higher schizotypy scores | Research

The takeaway

In 307 healthy adults, neither lifetime nor current cannabis use was associated with disrupted Kamin blocking (a learning measure impaired in schizophrenia), though current users scored higher on disorganized schizotypy and aberrant salience.

Psychosis researchers, cognitive neuroscientists, clinicians studying cannabis-psychosis mechanisms

No significant association between cannabis use and Kamin blocking performance

What the researchers found

Neither lifetime nor current cannabis use was associated with changes in Kamin blocking scores. However, current cannabis users had higher Disorganised SPQ dimension scores and higher total and sub-scale values on the Aberrant Salience Inventory. A modest positive link between Kamin blocking and disorganized schizotypy was observed.

Why it matters

The hypothesis that cannabis disrupts salience attribution (a proposed mechanism for psychosis) was not supported by this associative learning measure, even though cannabis users did show elevated self-reported schizotypy and aberrant salience.

The numbers in context

307 healthy participants; no significant association between cannabis use and Kamin blocking scores; current users had higher Disorganised SPQ and Aberrant Salience Inventory scores; higher "Senses Sharpening" ASI sub-scale predicted decreased Kamin blocking only in non-users

How the study worked

Cross-sectional online study of 307 healthy participants with no psychiatric history. Kamin blocking was measured using Oades' "mouse in the house task." Schizotypy was assessed with the Schizotypal Personality Questionnaire and aberrant salience with the Aberrant Salience Inventory. Cannabis use history was collected via the modified Cannabis Experience Questionnaire.

What this study cannot tell us

Cross-sectional design. Online behavioral testing platform may introduce noise. Non-clinical sample limits generalizability to those at clinical psychosis risk. Kamin blocking paradigm has shown inconsistent results across studies.

How to read the evidence

Adequately powered cross-sectional study with validated measures, but online testing and non-clinical sample limit interpretability.

When this study was published

Published in 2021.

The bigger picture

The disconnect between self-reported aberrant salience (elevated in cannabis users) and objective salience attribution performance (unchanged) raises questions about whether these measures tap the same construct, and whether the cannabis-psychosis pathway involves mechanisms beyond simple salience disruption.

Questions still open

Why do cannabis users report more aberrant salience experiences yet perform normally on an objective salience task? Does the Kamin blocking paradigm adequately capture the type of salience disruption relevant to cannabis-related psychosis risk?

Common questions

What is Kamin blocking?

Kamin blocking is a form of selective associative learning where prior learning about one cue "blocks" learning about a new cue. This blocking effect is disrupted in people with schizophrenia, possibly because they assign excessive importance (salience) to irrelevant stimuli.

Did cannabis affect any measures?

Yes. Current cannabis users scored higher on the Disorganised dimension of the Schizotypal Personality Questionnaire and on the Aberrant Salience Inventory. However, these self-reported differences did not translate to impaired performance on the objective learning task.

Read the original research

Cannabis Use, Schizotypy and Kamin Blocking Performance.

Frontiers in psychiatry, 12, 633476

View on PubMed ↗Publisher’s paper ↗

Citation

Dawes, Christopher; Bickerdike, Andrea; O'Neill, Cian; Carneiro Pereira, Sarah; Waddington, John L; Moran, Paula M; O'Tuathaigh, Colm M P. (2021). Cannabis Use, Schizotypy and Kamin Blocking Performance.. Frontiers in psychiatry, 12, 633476. https://doi.org/10.3389/fpsyt.2021.633476