Altered brain tissue composition in heavy marijuana users

Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, Maryland, United States
Drug and Alcohol Dependence (Impact Factor: 3.42). 02/2005; 77(1):23-30. DOI: 10.1016/j.drugalcdep.2004.06.011
Source: PubMed


Marijuana is the most widely used illicit substance in the United States; however, previous imaging studies have not detected altered brain structure in marijuana users compared to non-users. Voxel-based morphometry was used to investigate possible differences in brain tissue composition in a group of 11 heavy marijuana users and a group of 8 non-users. All participants were male. Statistical comparisons were made at the voxel level on T1-weighted magnetic resonance images to determine differences in gray matter and white matter tissue density. Compared to non-users, marijuana users had lower gray matter density in a cluster of voxels in the right parahippocampal gyrus (P = 0.0001), and greater density bilaterally near the precentral gyrus and the right thalamus (P < 0.04). Marijuana users also had lower white matter density in the left parietal lobe (P = 0.03), and higher density around the parahippocampal and fusiform gyri on the left side compared to non-users (P < 0.002). Longer duration of marijuana use (in years) was significantly correlated with higher white matter tissue density in the left precentral gyrus (P = 0.045). Our preliminary results suggest evidence of possible structural differences in the brain of heavy marijuana users, and localize regions for further investigation of the effects of marijuana in the brain.

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Available from: Jean Lud Cadet
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    • "Structural neuroimaging studies have indicated that volumes of several brain areas are smaller in heavy adult MJ users especially in areas enriched with cannabinoid 1 (CB1) receptors, such as medial temporal lobe, and prefrontal cortex (Lorenzetti et al., 2010). Studies of adult chronic MJ users note brain volume reductions in temporal lobe, insula, and prefrontal cortex, amygdala and hippocampus (Battistella et al., 2014; Cousijn et al., 2012; Filbey et al., 2014; Matochik et al., 2005; Yucel et al., 2008). Among different characteristics of MJ involvement (e.g., dependence symptoms, use frequency, consumption), the age of initial MJ use is a robust factor that has been associated with smaller brain volumes in users. "
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    ABSTRACT: Background: As the most commonly used illicit substance during early adolescence, long-term or latent effects of early adolescent marijuana use across adolescent developmental processes remain to be determined. Methods: We examined cortical thickness, gray/white matter border contrast (GWR) and local gyrification index (LGI) in 42 marijuana (MJ) users. Voxelwise regressions assessed early-onset (age <16) vs. late-onset (≥16 years-old) differences and relationships to continued use while controlling for current age and alcohol use. Results: Although groups did not differ by onset status, groups diverged in their correlations between cannabis use and cortical architecture. Among early-onset users, continued years of MJ use and current MJ consumption were associated with thicker cortex, increased GWR and decreased LGI. Late-onset users exhibited the opposite pattern. This divergence was observed in all three morphological measures in the anterior dorsolateral frontal cortex (p<.05, FWE-corrected). Conclusions: Divergent patterns between current MJ use and elements of cortical architecture were associated with early MJ use onset. Considering brain development in early adolescence, findings are consistent with disruptions in pruning. However, divergence with continued use for many years thereafter suggests altered trajectories of brain maturation during late adolescence and beyond.
    Full-text · Article · Oct 2015
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    • "Based on evidence from observational studies, cannabis use has been linked to a number of effects on cognition and behaviour (Ranganathan & D'Souza, 2006; Solowij & Pesa, 2010), with memory being one of the most robustly replicated cognitive functions which has been reported to be impaired following chronic (non-acute) cannabis use (Grant et al. 2003; Fletcher & Honey, 2006; Solowij & Battisti, 2008; Solowij & Pesa, 2010; Schoeler & Bhattacharyya, 2013). Meta-analyses of observational studies comparing cannabis-using subjects with nonusing subjects have reported small (Grant et al. 2003) to medium-sized effects (Schreiner & Dunn, 2012) of cannabis on verbal memory performance, consistent with evidence that regular cannabis use affects the structure (Matochik et al. 2005; Yucel et al. 2008) and function (Kanayama et al. 2004; Sneider et al. 2008) of brain regions involved in memory processing. As discussed by Solowij & Battisti (2008), accumulating evidence suggests that the magnitude and persistence of cognitive impairment associated with cannabis use depends on various parameters such as age of onset (Pope et al. 2003; Gruber et al. 2012), dose (Bolla et al. 2002), frequency (Jager et al. 2006; Tait et al. 2011), and duration of cannabis use (Meier et al. 2012) as well as the period of abstinence from cannabis (Pope * Address for correspondence: S. "
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    ABSTRACT: Background: Effect of cannabis use on memory function is a contentious issue, with effects being different in healthy individuals and patients with psychosis. Method: Employing a meta-analytic approach we investigated the effects of cannabis use on memory function in patients with psychosis and healthy individuals, and the effect of diagnosis, memory dimension and moderating factors. A total of 88 studies were identified through a systematic literature search, investigating healthy (n = 7697) and psychotic (n = 3261) individuals. Standardized mean differences between the cannabis user and non-user groups on memory tasks were estimated using random-effects models and the effect-size statistic Cohen's d. Effects of potential moderating factors were tested using mixed-effects models and subgroup analyses. Results: We found that cannabis use was associated with significantly (p ⩽ 0.05) impaired global (d = 0.27) and prospective memory (d = 0.61), verbal immediate (d = 0.40) and delayed (d = 0.36) recall as well as visual recognition (d = 0.41) in healthy individuals, but a better global memory (d = -0.11), visual immediate recall (d = -0.73) and recognition (d = -0.42) in patients. Lower depression scores and younger age appeared to attenuate the effects of cannabis on memory. Cannabis-using patients had lower levels of depression and were younger compared with non-using patients, whilst healthy cannabis-users had higher depression scores than age-matched non-users. Longer duration of abstinence from cannabis reduced the effects on memory in healthy and patient users. Conclusions: These results suggest that cannabis use is associated with a significant domain-specific impairment in memory in healthy individuals but not in cannabis-using patients, suggesting that they may represent a less developmentally impaired subgroup of psychotic patients.
    Full-text · Article · Sep 2015 · Psychological Medicine
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    • "Given the sub-optimal functional response of these a priori regions in MJ users during cognitive task performance, it is possible that surface-based cortical thickness analyses will reveal corresponding structural changes, with lower cortical thickness related to MJ use in these regions. Hippocampus, amygdala and thalamus, regions demonstrating high CB1 receptor distribution (Herkenham et al., 1991), also were selected for volumetric analysis based on evidence that MJ users exhibit functional and neurochemical alterations in these regions related to marijuana use (Ashtari et al., 2011; Bolla et al., 2005; Cousijn et al., 2012; Demirakca et al., 2011; Gilman et al., 2014; Glass et al., 1997; Hester et al., 2009; Mashhoon et al., 2013; Matochik et al., 2005; Schacht et al., 2012; Sneider et al., 2013a,b; Yucel et al., 2008). Clinical measures of mood and impulsivity were examined relative to cortical thickness and brain volume to further probe potential links with neurobiological consequences of marijuana use. "
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    ABSTRACT: The prevalence of marijuana (MJ) use among youth and its legalization for medical or recreational use has intensified public health endeavors of understanding MJ effects on brain structure and function. Studies indicate that MJ use is related to impaired cognitive performance, and altered functional brain activation and chemistry in adolescents and adults, but MJ effects on brain morphology in emerging adults are less understood. Fifteen MJ users (age 21.8±3.6, 2 females) and 15 non-user (NU) participants (age 22.3±3.5, 2 females) were included, demographically matched on age, education and alcohol use. High-resolution structural MR images were acquired at 3Tesla. Cortical thickness (CT) and volumetric analyses were performed using Freesurfer. A priori regions of interest (ROI) included orbitofrontal and cingulate cortices, amygdala, hippocampus and thalamus. Whole brain CT analysis did not result in significant group differences in a priori ROIs but revealed MJ users had significantly less CT (i.e., thinness) in right fusiform gyrus (rFG) compared to NU (p<0.05). Thalamic volume was significantly smaller in MJ users compared to NU (right, p=0.05; left, p=0.01) and associated with greater non-planning (p<0.01) and overall impulsivity (p=0.04). There were no other group differences. RFG cortical thinness and smaller thalamic volume in emerging adults is associated with MJ abuse. Furthermore, smaller thalamic volume associated with greater impulsivity contributes to growing evidence that the thalamus is neurobiologically perturbed by MJ use. Collectively, altered thalamic and rFG structural integrity may interfere with their known roles in regulating visuoperceptual and object information processing. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Full-text · Article · Jun 2015 · Drug and Alcohol Dependence
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