Brain imaging showed less damage in cannabis-induced psychosis compared to schizophrenia with cannabis use | Research

The takeaway

People with cannabis-induced psychosis had fewer white matter abnormalities and greater gray matter volume in key brain regions compared to those with schizophrenia who also used cannabis.

Psychiatrists distinguishing psychosis types, neuroscientists studying cannabis effects on brain structure, and people who have experienced cannabis-induced psychosis.

CIP had better white matter integrity in the corticospinal tract than SZC

What the researchers found

Participants with schizophrenia and cannabis use (SZC) had widespread white matter microstructural abnormalities, while those with cannabis-induced psychosis (CIP) had fewer WM disruptions and greater gray matter volumes in the cerebellum and frontal regions.

Why it matters

Understanding the brain differences between cannabis-induced psychosis and schizophrenia helps explain why some cannabis users develop temporary psychosis while others progress to a chronic condition.

The numbers in context

60 participants (20 per group). CIP and SZC groups had comparable cannabis use history. SZC showed lower fractional anisotropy in 5 brain regions vs controls. CIP had higher FA than SZC in the left corticospinal tract. CIP had greater cerebellar GM volume than SZC.

How the study worked

Cross-sectional study with three groups of 20 participants: cannabis-induced psychosis, schizophrenia with cannabis use, and controls without substance use. Used diffusion tensor and kurtosis imaging for white matter analysis and voxel-based morphometry for gray matter.

What this study cannot tell us

Small sample size of 20 per group. Cross-sectional design cannot determine whether brain differences preceded or resulted from the conditions. Convenience sampling may limit representativeness.

How to read the evidence

Preliminary: small sample (20 per group), cross-sectional design, convenience sampling.

When this study was published

Published in 2022.

The bigger picture

These structural brain differences may help explain why cannabis-induced psychosis is often temporary while schizophrenia is chronic, and could eventually help clinicians predict which cannabis users are at risk for progression.

Questions still open

Could these brain imaging differences be used clinically to distinguish CIP from early schizophrenia? Do the greater gray matter volumes in CIP protect against progression to schizophrenia? Would longitudinal imaging show changes over time?

Common questions

What is the difference between cannabis-induced psychosis and schizophrenia?

Cannabis-induced psychosis (CIP) is a psychotic episode triggered by cannabis use that typically resolves. Schizophrenia is a chronic condition. Some people who use cannabis and develop psychosis may already have underlying schizophrenia.

What do the brain differences suggest?

Better white matter integrity and greater gray matter volumes in CIP may serve as protective factors against progression to chronic schizophrenia, though this is a hypothesis that needs longitudinal testing.

Did the two psychosis groups use cannabis differently?

No. The CIP and SZC groups had comparable age at cannabis initiation and similar duration and frequency of use, suggesting the brain differences were not due to different cannabis exposure.

Read the original research

White Matter Microstructure and Gray Matter Volume in Cannabis-Induced Psychosis and Schizophrenia With Cannabis Use.

The Journal of neuropsychiatry and clinical neurosciences, 34(4), 406-413

View on PubMed ↗Publisher’s paper ↗

Citation

Shah, Raghav; Ghosh, Abhishek; Avasthi, Ajit; Ahuja, Chirag K; Khandelwal, Niranjan; Nehra, Ritu. (2022). White Matter Microstructure and Gray Matter Volume in Cannabis-Induced Psychosis and Schizophrenia With Cannabis Use.. The Journal of neuropsychiatry and clinical neurosciences, 34(4), 406-413. https://doi.org/10.1176/appi.neuropsych.21070172