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Comparative Study
. 2014 Aug;39(9):2041-8.
doi: 10.1038/npp.2014.67. Epub 2014 Mar 17.

Long-term effects of cannabis on brain structure

Affiliations
Comparative Study

Long-term effects of cannabis on brain structure

Giovanni Battistella et al. Neuropsychopharmacology. 2014 Aug.

Abstract

The dose-dependent toxicity of the main psychoactive component of cannabis in brain regions rich in cannabinoid CB1 receptors is well known in animal studies. However, research in humans does not show common findings across studies regarding the brain regions that are affected after long-term exposure to cannabis. In the present study, we investigate (using Voxel-based Morphometry) gray matter changes in a group of regular cannabis smokers in comparison with a group of occasional smokers matched by the years of cannabis use. We provide evidence that regular cannabis use is associated with gray matter volume reduction in the medial temporal cortex, temporal pole, parahippocampal gyrus, insula, and orbitofrontal cortex; these regions are rich in cannabinoid CB1 receptors and functionally associated with motivational, emotional, and affective processing. Furthermore, these changes correlate with the frequency of cannabis use in the 3 months before inclusion in the study. The age of onset of drug use also influences the magnitude of these changes. Significant gray matter volume reduction could result either from heavy consumption unrelated to the age of onset or instead from recreational cannabis use initiated at an adolescent age. In contrast, the larger gray matter volume detected in the cerebellum of regular smokers without any correlation with the monthly consumption of cannabis may be related to developmental (ontogenic) processes that occur in adolescence.

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Figures

Figure 1
Figure 1
Voxel-Based Morphometry results on gray matter. Cold color bar shows regions where gray matter volume is lower in regular smokers compared with occasional ones. Hot color bar represents the opposite contrast. Maps are thresholded at P<0.005 and k>60 and superposed on a standard brain in the MNI space. Figure shows results in planes centered at −26, 7, 14 mm and −48, 10, −19 mm. Color bars represent T score.
Figure 2
Figure 2
(a) Correlation between the modulated gray matter intensity at the center of gravity of the significant clusters and the monthly frequency of joints smoked during 3 months before inclusion in the study. Lines represent the fitting of the distribution of the values. Pearson's correlation coefficient and P-value are shown at the bottom of each plot. (b) Mean GM volume across the four subgroups (Occasional late, Occasional early, Regular late, Regular early). Whiskers represent 95% confidence interval, horizontal lines represent significant comparisons and stars the significance level (P<0.05).

References

    1. Albein-Urios N, Martinez-Gonzalez JM, Lozano O, Moreno-López L, Soriano-Mas C, Verdejo-Garcia A. Negative urgency, disinhibition and reduced temporal pole gray matter characterize the comorbidity of cocaine dependence and personality disorders. Drug Alcohol Depend. 2013;132:231–237. - PubMed
    1. Ashburner J. A fast diffeomorphic image registration algorithm. Neuroimage. 2007;38:95–113. - PubMed
    1. Ashburner J, Friston KJ. Unified segmentation. Neuroimage. 2005;26:839–851. - PubMed
    1. Ashtari M, Avants B, Cyckowski L, Cervellione KL, Roofeh D, Cook P, et al. Medial temporal structures and memory functions in adolescents with heavy cannabis use. J Psychiatr Res. 2011;45:1055–1066. - PMC - PubMed
    1. Batalla A, Bhattacharyya S, Yücel M, Fusar-Poli P, Crippa JA, Nogué S, et al. Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings. PLoS ONE. 2013;8:e55821. - PMC - PubMed

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