Heavy Cannabis Use Did Not Impair Basic Motor Function on Brain Scans
BOLD-fMRI brain scans showed no significant differences in motor cortex activation between heavy cannabis users (15 joints/day), moderate users, and light users, suggesting motor function is preserved despite chronic use.
Quick Facts
What This Study Found
Three groups of cannabis users (heavy: 15 joints/day, moderate: 1.5 joints/day, light: 2.8 joints/week) plus healthy controls showed no significant differences in motor cortex activation patterns during fMRI-assessed motor tasks. Brain plasticity and reorganization of motor control appeared equivalent across all groups.
Key Numbers
23 cannabis users in 3 groups: 11 heavy (15 joints/day), 6 moderate (1.5 joints/day), 6 light (2.8 joints/week); 6 healthy controls; no significant differences in BOLD-fMRI motor activation across groups
How They Did This
23 cannabis users divided into three consumption groups plus 6 healthy controls underwent BOLD-fMRI assessments of motor function, along with neuropsychological and biological assessments.
Why This Research Matters
While cannabis is known to affect cognition and memory, this study suggests that basic motor cortex function may be resilient to chronic use, even at very high consumption levels. This distinction between preserved and impaired brain functions could inform understanding of cannabis effects on the brain.
The Bigger Picture
Understanding which brain functions are affected by chronic cannabis use and which are preserved helps build a more nuanced picture than the common assumption that cannabis broadly impairs brain function.
What This Study Doesn't Tell Us
Very small sample sizes per group (6-11 participants), cross-sectional design cannot rule out pre-existing differences, only motor function tested, no control for acute intoxication at time of scan, limited to cortical motor areas
Questions This Raises
- ?Would more sensitive motor tasks reveal subtle differences?
- ?Are other motor-related brain areas (cerebellum, basal ganglia) affected even if primary motor cortex is not?
- ?Does preserved motor function extend to fine motor skills and coordination?
Trust & Context
- Key Stat:
- No motor function differences found between users consuming 15 joints/day and non-users
- Evidence Grade:
- Very small study (29 total participants) with limited statistical power; interesting null finding but sample too small for confident conclusions
- Study Age:
- Published 2025
- Original Title:
- Heavy and Chronic Cannabis Addiction does not Impact Motor Function: A BOLD-fMRI Study.
- Published In:
- CNS & neurological disorders drug targets, 24(6), 475-490 (2025)
- Authors:
- Boujraf, Saïd, Alami, Badreeddine, Chikri, Mohamed, El Hamdaoui, Halima, Maaroufi, Mustapha, Aalouane, Rachid, Rammouz, Ismail
- Database ID:
- RTHC-06106
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does chronic cannabis use affect motor function?
In this small fMRI study, even heavy cannabis users (15 joints/day) showed no significant differences in motor cortex activation compared to non-users, suggesting basic motor control may be preserved despite heavy use.
How should this null finding be interpreted?
With only 29 total participants in 4 groups, the study may simply lack the statistical power to detect real differences. The finding is suggestive but needs replication in larger samples.
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Cite This Study
https://rethinkthc.com/research/RTHC-06106APA
Boujraf, Saïd; Alami, Badreeddine; Chikri, Mohamed; El Hamdaoui, Halima; Maaroufi, Mustapha; Aalouane, Rachid; Rammouz, Ismail. (2025). Heavy and Chronic Cannabis Addiction does not Impact Motor Function: A BOLD-fMRI Study.. CNS & neurological disorders drug targets, 24(6), 475-490. https://doi.org/10.2174/1574886317666220516103501
MLA
Boujraf, Saïd, et al. "Heavy and Chronic Cannabis Addiction does not Impact Motor Function: A BOLD-fMRI Study.." CNS & neurological disorders drug targets, 2025. https://doi.org/10.2174/1574886317666220516103501
RethinkTHC
RethinkTHC Research Database. "Heavy and Chronic Cannabis Addiction does not Impact Motor F..." RTHC-06106. Retrieved from https://rethinkthc.com/research/boujraf-2025-heavy-and-chronic-cannabis
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.