Among 60 participants, male cannabis users showed significantly slower psychomotor performance, shifted brain activation from visual to executive control regions, and higher cortisol levels compared to controls.
Read this if you want to understand how chronic cannabis use affects motor skills and stress hormones differently in men and women.
Male cannabis users significantly slower; cortisol elevated (p=0.002)
What the researchers found
Thirty cannabis users (16 men, 14 women) and 30 matched controls were tested with neuropsychological assessments and fMRI during a finger-sequencing task.
Male, but not female, cannabis users had significantly slower psychomotor speed. As a group, cannabis users showed greater activation in a motor planning region (BA 6) but reduced activation in a primary visual area (BA 17) compared to controls.
This shift from visual processing regions to executive/attentional control areas suggested cannabis users relied on more effortful, less automated motor control. Cannabis users also had significantly higher salivary cortisol levels (p=0.002).
The authors proposed that elevated cortisol from chronic cannabis use may mediate the altered brain activation patterns and reduced motor efficiency.
Why it matters
The sex-specific finding (males affected, females not) and the cortisol elevation provided mechanistic insights into how chronic cannabis use may disrupt motor function through stress hormone pathways.
The numbers in context
30 cannabis users vs 30 controls. Male users significantly slower on psychomotor tests. Greater BA 6 activation, reduced BA 17 activation in users. Salivary cortisol significantly higher (p=0.002) in cannabis users.
How the study worked
Cross-sectional study comparing 30 chronic active cannabis users (16M, 14F, ages 18-45) to 30 non-drug-using controls (16M, 14F, ages 19-44). fMRI during visually paced finger sequencing at 2 and 4 Hz. Salivary cortisol measured. Neuropsychological motor tests administered.
What this study cannot tell us
Cross-sectional design. Cannot determine whether cannabis caused the cortisol elevation or brain changes. Active cannabis users were tested, so acute intoxication effects cannot be fully separated from chronic effects.
How to read the evidence
Well-matched cross-sectional fMRI study with sex-specific analysis but unable to establish causation.
When this study was published
Published in 2011. Research on sex differences in cannabis effects has expanded.
The bigger picture
The cortisol-mediated mechanism linked cannabis use to the stress response system, suggesting chronic use may alter hypothalamic-pituitary-adrenal (HPA) axis function in ways that affect brain efficiency.
Questions still open
- Why were male users more affected than females? Would cortisol levels and brain activation patterns normalize with abstinence?
Common questions
Does cannabis make you slower?
Does cannabis affect cortisol?
Read the original research
Altered brain activation during visuomotor integration in chronic active cannabis users: relationship to cortisol levels.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 31(49), 17923-31
Citation
King, George R; Ernst, Thomas; Deng, Weiran; Stenger, Andrew; Gonzales, Rachael M K; Nakama, Helenna; Chang, Linda. (2011). Altered brain activation during visuomotor integration in chronic active cannabis users: relationship to cortisol levels.. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31(49), 17923-31. https://doi.org/10.1523/JNEUROSCI.4148-11.2011
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