Brain Development of Adolescent Marijuana Users

描述(由申请人提供)： 这项拟议的研究将考察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，而在青春期较早开始使用且使用时间更长的人，这种功能障碍更严重，那么潜在的社会成本可能会很高。利用正电子发射断层扫描和磁共振成像，我们将检测长期吸食大麻的受试者与对照组在基线局部脑血流量和认知相关的局部脑血流量变化(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方面的差异。我们假设长期吸食大麻的人与对照组不同，这些差异在初次使用年龄较早、使用时间较长的吸食大麻的人中会更加明显。假设长期使用大麻对小脑后部、前额叶皮质和海马区局部脑血流的影响是拟议研究的重点。如果假设的影响发生，它们将提供证据，证明长期吸食大麻会改变大脑功能，而且通常发生在青春期的明显大脑发育增加了对这种变化的易感性。 此外，还将在不涉及神经成像的课程中进行更广泛的认知测试，以测试这样一个假设，即首次使用大麻的年龄更早、使用时间更长的人，使用大麻的认知影响也更明显。受试者分组将使用标准化考试成绩记录进行疾病前智力功能的匹配，这些成绩可以在爱荷华州几乎所有地区接受教育的儿童获得。除了我们的研究以外，没有发表的研究表明，与患病前智力功能匹配的对照受试者相比，长期吸食大麻的人的大脑功能和认知能力发生了变化。完成后，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做出重要补充。

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.