Brain Development of Adolescent Marijuana Users

描述（由申请人提供）： 这项拟议中的研究将研究首次使用大麻的年龄和使用时间对大脑功能、大脑结构和认知的影响。考虑到大麻是使用最广泛的非法药物，如果长期使用会使一些大麻使用者产生脑功能障碍，而这种功能障碍在青少年时期开始使用较早和使用时间较长的人中更严重，那么社会的潜在成本可能会很高。使用正电子发射断层扫描和磁共振成像，我们将研究慢性大麻使用者与对照组在基线局部脑血流量和局部脑血流量（记忆，敲击和赌博测试）中认知相关变化的差异，以及全脑血流量和脑组织体积和组成。我们假设，慢性大麻使用者将不同于对照组，这些差异将在大麻使用者中更明显，首次使用的年龄更早，使用时间更长。假设长期使用大麻对小脑后部、前额皮质和海马的局部脑血流的影响是拟议研究的特别焦点。 如果假设的影响发生，他们将提供证据表明，长期使用大麻会改变大脑功能，而通常在青春期发生的明显的大脑发育会增加对这种改变的脆弱性。 此外，更广泛的认知测试将在不涉及神经成像的会议中进行，以测试大麻使用的认知影响在首次使用年龄较早和使用时间较长的个体中也更明显的假设。受试者组将使用标准化测试分数记录进行病前智力功能的匹配，这些记录可用于爱荷华州几乎所有地区接受教育的儿童。除了我们的研究之外，没有发表过的研究表明慢性大麻使用者的大脑功能和认知能力相对于对照组的疾病前智力功能发生了变化。完成后，拟议中的研究将为有关长期使用大麻对人脑功能，大脑结构和认知的影响的知识提供重要补充。

DESCRIPTION (provided by applicant): The proposed research will examine effects of age of first use of marijuana and duration of use on brain function, brain structure, and cognition. Considering that marijuana is the most widely used illicit drug, if chronic use produces brain dysfunction in some marijuana users and this dysfunction is greater in those who begin use earlier during adolescence and use longer, the potential costs to society could be high. Using positron emission tomography and magnetic resonance imaging, we will examine differences of chronic marijuana users from control subjects in baseline regional cerebral blood flow and cognition-related changes in regional cerebral blood flow (in memory, tapping and gambling tests), as well as whole brain blood flow and brain tissue volume and composition. We hypothesize that chronic marijuana users will differ from control subjects and these differences will be more pronounced in marijuana users with earlier ages of first use and longer durations of use. Hypothesized effects of chronic marijuana use on regional cerebral blood flow in posterior cerebellum, prefrontal cortex, and hippocampus are particular foci of the proposed research. If the hypothesized effects occur, they will provide evidence that chronic marijuana use alters brain functioning and that the pronounced brain development that normally occurs during adolescence increases vulnerability to such alterations. Additional, more extensive cognitive tests will be administered in sessions not involving neuroimaging to test the hypothesis that cognitive effects of marijuana use are also more pronounced in individuals with earlier ages of first use and longer durations of use. Groups of subjects will be matched on premorbid intellectual functioning using records of standardized test scores that are available for children educated in virtually all parts of Iowa. No published studies except ours have demonstrated changes in brain function and cognition in chronic marijuana users relative to control subjects matched on premorbid intellectual functioning. When completed, the proposed research will make important additions to knowledge about effects of chronic marijuana use on human brain function, brain structure, and cognition.