Non-Right-Handedness in Schizophrenia Linked to Cannabis Use Disorder

What the researchers found

Among 667 schizophrenia patients, 42.4% were non-right-handed and 34.1% mixed-handed. Non-right-handedness was associated with cannabis use disorder (P=0.045) and learning disorders. Mixed-handedness was associated with positive symptoms (P=0.041), current depression (P=0.005), current cannabis use (P=0.024), and less akathisia (P=0.019).

Why it matters

Non-right-handedness is considered a marker of atypical neurodevelopment. Its association with cannabis use disorder in schizophrenia suggests shared developmental vulnerabilities may underlie both traits.

The numbers in context

667 participants; 42.4% non-right-handed; 34.1% mixed-handed; NRH associated with CUD (P=0.045); mixed-handedness with current cannabis use (P=0.024)

How the study worked

Cross-sectional study of 667 participants from the FACE-SZ cohort assessed with the Edinburgh Handedness Inventory, neuropsychological testing, and clinical symptom measures.

What this study cannot tell us

Cross-sectional design cannot determine direction of associations. Handedness was self-reported. Cannabis use assessment relied on clinical records.

How to read the evidence

Large cohort with validated assessments, but cross-sectional design limits causal interpretation.

When this study was published

Published in 2022

The bigger picture

The very high rate of atypical handedness in this schizophrenia cohort (42.4% vs ~10% in the general population) reflects neurodevelopmental disruption that may also predispose to substance use.

Questions still open

• Does the shared neurodevelopmental basis for non-right-handedness and cannabis use disorder suggest a common genetic pathway? Would early identification of atypical handedness in psychosis patients flag higher substance use risk?

Common questions

Read the original research

Handedness as a neurodevelopmental marker in schizophrenia: Results from the FACE-SZ cohort.

The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry, 23(7), 525-536

Citation

Mallet, Jasmina; Godin, Ophélia; Le Strat, Yann; Mazer, Nicolas; Berna, Fabrice; Boyer, Laurent; Capdevielle, Delphine; Clauss, Julie; Chéreau, Isabelle; D'Amato, Thierry; Dubreucq, Julien; Leigner, Sylvain; Llorca, Pierre-Michel; Misdrahi, David; Passerieux, Christine; Rey, Romain; Pignon, Baptiste; Urbach, Mathieu; Schürhoff, Franck; Fond, Guillaume; Dubertret, Caroline. (2022). Handedness as a neurodevelopmental marker in schizophrenia: Results from the FACE-SZ cohort.. The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry, 23(7), 525-536. https://doi.org/10.1080/15622975.2021.2013094

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