Medical cannabis patients showed improved brain white matter structure after 3-6 months of treatment, with CBD exposure linked to improvements | Research

The takeaway

Medical cannabis patients showed increased white matter coherence on MRI after 3 and 6 months of treatment, contrasting with impairments typically seen in recreational users, with improvements correlated to CBD exposure.

Neuroscientists, medical cannabis patients, clinicians, and researchers studying cannabinoid neuroprotection.

White matter improved (not worsened) with medical cannabis use; CBD linked to gains

What the researchers found

FA values (indicating white matter integrity) significantly increased in corpus callosum regions after 3 and 6 months of MC treatment. MD values (indicating demyelination when elevated) significantly decreased after 6 months. No changes were seen in a control brain region or in a pilot treatment-as-usual group. Reduced MD correlated with higher CBD but not THC exposure.

Why it matters

This is the first study showing improved (not worsened) white matter coherence with cannabis use, suggesting medical cannabis patients, who tend to use CBD-containing products and start at older ages, may experience fundamentally different neural effects than recreational users.

The numbers in context

37 MC patients; FA increased bilaterally in callosal regions at 3 and 6 months. MD decreased after 6 months. CBD exposure correlated with MD reduction. No changes in 14 treatment-as-usual controls.

How the study worked

Longitudinal study of 37 MC patients assessed via diffusion tensor imaging (DTI-MRI) before starting MC and at 3 and 6 months. Bilateral regions of interest including corpus callosum and internal capsule analyzed. A pilot treatment-as-usual comparison group (n=14) also assessed.

What this study cannot tell us

Small sample with attrition (37 to 22 over 6 months). Open-label, non-randomized. Patients chose their own products. Pilot control group was very small (n=14). Cannot separate MC effects from natural recovery from symptoms MC was treating.

How to read the evidence

Longitudinal MRI study with pilot control group, but small sample and open-label design.

When this study was published

Published in 2022.

The bigger picture

The contrast with recreational cannabis research, which typically shows white matter impairment, suggests the context of use matters enormously: product choice (CBD content), age of onset, and motivation for use may all influence neural outcomes.

Questions still open

Is CBD driving the white matter improvements? Would recreational users who switch to CBD-rich products show similar improvements? Are the white matter changes clinically meaningful?

Common questions

Does medical cannabis damage the brain?

This study found the opposite: medical cannabis patients showed improved white matter structure on brain MRI over 6 months, contrasting with findings in recreational users. The improvements were linked to CBD exposure.

Why might medical cannabis be different from recreational use?

Medical cannabis patients typically start later in life, choose products with higher CBD content, and use for therapeutic purposes. These differences may explain why they showed brain improvements rather than the impairments seen in studies of recreational users.

Read the original research

Increased White Matter Coherence Following Three and Six Months of Medical Cannabis Treatment.

Cannabis and cannabinoid research, 7(6), 827-839

View on PubMed ↗Publisher’s paper ↗

Citation

Dahlgren, Mary Kathryn; Gonenc, Atilla; Sagar, Kelly A; Smith, Rosemary T; Lambros, Ashley M; El-Abboud, Celine; Gruber, Staci A. (2022). Increased White Matter Coherence Following Three and Six Months of Medical Cannabis Treatment.. Cannabis and cannabinoid research, 7(6), 827-839. https://doi.org/10.1089/can.2022.0097