Evidence for reduced frontal cortical thickness in long-term heavy cannabis users
A. Aquino-Servin, P. Fuentes-Claramonte, N. Hostalet, I. París-Gómez, P. del Olmo-Encabo, M. Madre, X. Roca, F. Panicali, A. Romaguera, M. Á. García-León, P. J. McKenna, E. Pomarol-ClotetIntroduction
Although cannabis use is often regarded as relatively harmless, structural imaging studies have found variable evidence for volume reductions in the hippocampus and orbitofrontal cortex (OFC) among other regions (Lorenzetti et al. Eur Arch Psychiatry Clin Neurosci; 269 59-71; Soleimani et al. Sci Rep 2023; 13 5847; Mashhoon et al. Drug Alcohol Depend. 2015; 155 275-83; Wittemann et al. Eur. Addict. Res. 2021; 27 115-22). These studies have mostly focused on adolescents and young adult users, and studies in long-term, heavy cannabis users, who would be arguably most likely to show structural alterations, are few.
Objectives
The aim of this study is to examine different morphological metrics at the whole-brain level, including volume, surface area and cortical thickness in long-term, heavy cannabis users.
Methods
We carried out 3T structural imaging in 41 cannabis users with ≥10 years of use and ≥5 years of daily consumption (mean age 31.3 ± 6.97 years), and 40 age, sex, and IQ (measured using the Test de Acentuación de Palabras (Del Ser et al 1999 Brain Cogn; 33 343-56), and non-using controls (<10 lifetime uses). Structural MRI data were processed in FreeSurfer (v7.1.1), to provide measures of surface area, and cortical thickness. Whole-brain, non-parametric permutation testing was conducted with cluster-wise correction (p < .001, two-tailed; 5,000 Monte Carlo iterations), and clusters were considered significant at a corrected p of < .05.
Results
The cannabis users showed two clusters of cortical thickness reduction in the right rostral middle frontal cortex (See Fig1) (max=3.37, cluster=657.94 vertices, p=0.01; max=4.46, cluster=531.57 vertices, p=0.02). No differences were observed in cortical volume or surface area.
Image 1: Long description.