Effects of Marijuana on the Brain Essay - 550 Words

Effects of Marijuana on the Brain (Article Sample) Content: Filbey, F.M., Aslan, S., Calhoun, V.D., Spence, J.S., ... Segall, J. (2014). Long-term effects of marijuana use on the brain. PNAS , 111 (47):16913-16918. Retrieved from /cgi/doi/10.1073/pnas.1415297111.NameUniversityIntroduction According to Filbey et al. (2014), Marijuana use has steadily increased yet research findings on neural changes associated with chronic marijuana use remain equivocal despite agreement that such changes affect neural architecture, arguing from the knowledge that cognitive changes associated with chronic marijuana use are long lasting. The authors appreciate research focus on cannabinoid 1 (CB1) receptor-rich brain areas that includes orbitofrontal cortex in studying neuronal changes secondary to marijuana use: Tetrahydrocannabinoid (THC), the main ingredient in marijuana binds to CB1 receptors. However, the authors were disturbed by paradoxical results of studies assessing neural architecture changes, which showed increase, decrease, and no d ifferences in regional or global volume white or gray matter volume. Informed by findings linking brain structure and connectivity, the authors sought to determine structural brain alterations and potential patterns of gray matter connectivity emanating from chronic marijuana use.Materials and methods The researchers applied a case-control design with a sample population of 110 participants out of which 48 were chronic marijuana users (cases) whereas 62 were non-marijuana users (controls). Inclusion criteria for the cases were self-reported regular (minimum four times a week) marijuana use for at least 6 months and a positive THC-COOH urine test. Importantly, the researchers removed confounding by excluding persons who had current and/or previous history of traumatic brain injury, psychosis, and neurological disorder from the cannabis group. However, there is no evidence of randomization at recruitment stage although both cases and controls were matched for sex. All the participants were then subjected to magnetic resonance imaging (MRI) of the brain and interviewed using Marijuana Problem Survey tool to capture structural changes and behavioral measures respectively. Specifically, a high resolution T1-weighted image, a resting state functional MRI, and a diffusion tensor imaging scan were collected to measure gray matter volume, assess functional connectivity, and assess structural connectivity between white matter tracts and brain regions respectively. Behavioral data was analyzed against a pre-developed Likert scale whereas voxel-based morphology technique for investigating structural abnormalities of the whole brain was used to process MRI data. Notably, the researchers performed linear regression analysis to assess contribution of chronic cannabis use on gray matter volume, cognition, functional connectivity, and structural connectivity. Besides, t-tests were performed to test the hypothesis that chronic marijuana use has no effect on gray matter volume, cognition, functional connectivity, and structural connectivity. Additionally, parametric regression models analyzed relationship among aforementioned variables.Results According to Filbey et al. (2014), the results were that chronic marijuana users develop structural alterations evidenced by significantly reduced orbitofrontal gyri volume bilaterally. Besides, the researchers identified structural and functional connectivity changes exem...