BRAIN DEVELOPMENT OF ADOLESCENT MARIJUANA USERS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。这项研究将检验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，如果长期使用大麻会导致一些大麻使用者的大脑功能障碍，而那些在青春期开始使用大麻更早、使用时间更长的人的大脑功能障碍更大，那么对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，我们将检查慢性大麻使用者和对照组在基线区域脑血流量和认知相关的区域脑血流量变化（在记忆，敲击和赌博测试中），以及全脑血流量和脑组织体积和组成的差异。我们假设慢性大麻使用者与对照受试者不同，这些差异在首次使用大麻的年龄较早和使用时间较长的大麻使用者中更为明显。长期使用大麻对小脑后部、前额叶皮层和海马区域脑血流的假设影响是拟议研究的特别重点。如果假设的影响发生，他们将提供证据，证明长期使用大麻会改变大脑功能，而通常发生在青少年时期的明显大脑发育会增加对这种改变的脆弱性。此外，将在不涉及神经成像的会议上进行更广泛的认知测试，以验证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为明显的假设。各组受试者将根据发病前的智力功能进行匹配，使用的是爱荷华州几乎所有地区受教育儿童的标准化考试成绩记录。一旦完成，这项拟议的研究将对长期使用大麻对人类大脑功能、大脑结构和认知的影响的知识做出重要补充。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This research will examine the 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 between chronic marijuana users and 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 function using records of standardized test scores that are available for children educated in virtually all parts of Iowa. 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.