Impaired verbal learning and reduced medial temporal volumes in long-term heavy cannabis users

Abstract

Event Abstract Back to Event Impaired verbal learning and reduced medial temporal volumes in long-term heavy cannabis users Murat Yücel1, 2*, M. Solowij3, 4, S. Whittle1, 2, C. Respondek3, Alex Fornito2, C. Pantelis2 and D. I. Lubman1 1 ORYGEN Research Centre, Australia 2 The University of Melbourne and Melbourne Health , Australia 3 University of Wollongong , Australia 4 Schizophrenia Research Institute, Australia Background: Cannabis is the most widely used illicit drug in the developed world. Despite this, there is a paucity of research examining its long-term impact on the human brain. Our aim was to determine whether long-term and heavy cannabis use is associated with verbal learning deficits and gross anatomical abnormalities in two cannabinoid receptor rich regions of the brain, the hippocampus and amygdala. Method: A cross-sectional design using high-resolution (3-Tesla) structural magnetic resonance imaging (MRI) was utilised. Participants were recruited from the general community and scanned at a hospital research facility. Fifteen carefully selected long-term (>10 years duration) and heavy (>5 joints per day) cannabis-using males (mean age 39.8 years; 19.7 years of regular use) with no history of polydrug abuse or neurological/mental disorder, and 16 matched non-using healthy volunteers (mean age 36.4 years). Volumetric measures of hippocampus and amygdala, combined with measures of cannabis use. Subthreshold psychotic symptoms and verbal learning ability were also measured. Results: Cannabis users had bilaterally reduced hippocampal and amygdala volumes (P=0.001) with a relatively (and significantly; P=0.018) greater magnitude of reduction in the former (12.0% in hippocampus vs 7.1% in amygdala). Left hippocampal volume was inversely associated with cumulative dose of cannabis use over the previous 10 years (P=0.014), as well as subthreshold positive psychotic symptoms (P<0.001). Positive symptom scores were also associated with cumulative dose of cannabis used (P= 0.048). While cannabis users performed significantly worse than controls on verbal learning (P= 0.0005), this did not correlate with regional brain volumes in either group. Conclusions: Our results provide new evidence of dose-related structural abnormalities in the hippocampus and amygdala of long-term heavy cannabis users, and corroborate similar findings within the animal literature. These findings indicate that heavy daily cannabis use over protracted periods exerts harmful effects on brain tissue and mental health. Conference: 10th International Conference on Cognitive Neuroscience, Bodrum, Turkey, 1 Sep - 5 Sep, 2008. Presentation Type: Oral Presentation Topic: Memory & Learning Citation: Yücel M, Solowij M, Whittle S, Respondek C, Fornito A, Pantelis C and Lubman DI (2008). Impaired verbal learning and reduced medial temporal volumes in long-term heavy cannabis users. Conference Abstract: 10th International Conference on Cognitive Neuroscience. doi: 10.3389/conf.neuro.09.2009.01.259 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 Dec 2008; Published Online: 09 Dec 2008. * Correspondence: Murat Yücel, ORYGEN Research Centre, Melbourne, VIC., Australia, murat.yucel@monash.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Murat Yücel M. Solowij S. Whittle C. Respondek Alex Fornito C. Pantelis D. I Lubman Google Murat Yücel M. Solowij S. Whittle C. Respondek Alex Fornito C. Pantelis D. I Lubman Google Scholar Murat Yücel M. Solowij S. Whittle C. Respondek Alex Fornito C. Pantelis D. I Lubman PubMed Murat Yücel M. Solowij S. Whittle C. Respondek Alex Fornito C. Pantelis D. I Lubman Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.