Exercise-induced brain changes in cannabis use disorder: a longitudinal MRI study of a 12-week supervised HIIT...

Cannabis use disorder (CUD) is highly relapsing and has been associated with structural brain alterations (e.g., white matter and cortical thickness) in pathways and regions critical for a healthy brain. The development of non-abstinence-based interventions is essential for restoring structural alterations in CUD. Physical exercise, particularly aerobic exercise, may promote neuroplastic changes in brain structure.

In this novel randomised, single-blind, comparator-controlled trial, we recruited 59 individuals with CUD (76% classified with severe CUD; median age = 25 years, 22% female, without requiring abstinence during intervention). They were randomly allocated to receive 12-weeks of 45 min, three times/week of either: (i) High Intensity Interval Training (HIIT) aimed to achieve 80% of participants' maximum heart rate (above the lactate release threshold); or (ii) active control Strength and Resistance training (S&R). The main outcome was brain structural organisation (fractional anisotropy and cortical thickness) measured via advanced diffusion and anatomical MRI scans conducted before and after 12 weeks.

The HIIT group showed significant increases in FA in the left uncinate fasciculus (p = 0.012) and cortical thickness in the right pars opercularis of the inferior frontal gyrus (p = 0.016), revealed by time-by-group interaction. These exercise-induced changes in white matter and cortical thickness significantly correlated with total hours spent with heart rates > 80% (r = 0.32, p = 0.027 and r = 0.41, p = 0.001) and the time spent above the lactate release threshold (r = 0.27, p = 0.061 and r = 0.40, p = 0.004).

Overall, a 12-week HIIT exercise intervention, without requiring abstinence from cannabis consumption, can enhance brain plasticity.