Brain Mind and Society Research Hub, Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, Australia.
J Dual Diagn. 2020 Jan-Mar;16(1):83-105. doi: 10.1080/15504263.2019.1636171. Epub 2019 Jul 16.
Shifting policies and widespread acceptance of cannabis for medical and/or recreational purposes have fueled worries of increased cannabis initiation and use in adolescents. In particular, the adolescent period is thought to be associated with an increased susceptibility to the potential harms of repeated cannabis use, due to being a critical period for neuromaturational events in the brain. This review investigates the neuroimaging evidence of brain harms attributable to adolescent cannabis use. PubMed and Scopus searches were conducted for empirical articles that examined neuroimaging effects in both adolescent cannabis users and adult user studies that explored the effect of age at cannabis use onset on the brain. We found 43 studies that examined brain effect (structural and functional magnetic resonance imaging) in adolescent cannabis users and 20 that examined the link between onset age of cannabis use and brain effects in adult users. Studies on adolescent cannabis users relative to nonusers mainly implicate frontal and parietal regions and associated brain activation in relation to inhibitory control, reward, and memory. However, studies in adults are more mixed, many of which did not observe an effect of onset age of cannabis use on brain imaging metrics. While there is some evidence of compromised frontoparietal structure and function in adolescent cannabis use, it remains unclear whether the observed effects are specifically attributable to adolescent onset of use or general cannabis use-related factors such as depressive symptoms. The relative contribution of adolescent onset of cannabis use and use chronicity will have to be more comprehensively examined in prospective, longitudinal studies with more rigorous measures of cannabis use (dosage, exposure, dependence, constituent compounds such as the relative cannabinoid levels).
政策的转变和大麻在医学和/或娱乐方面的广泛接受，引发了人们对青少年中大麻使用增加的担忧。特别是，青少年时期被认为与反复使用大麻的潜在危害的易感性增加有关，因为这是大脑神经成熟事件的关键时期。本综述调查了归因于青少年大麻使用的大脑损伤的神经影像学证据。在 PubMed 和 Scopus 上进行了检索，以寻找研究青少年大麻使用者的神经影像学效应的实证文章，以及研究大麻使用起始年龄对大脑影响的成年使用者研究。我们发现了 43 项研究，这些研究检查了青少年大麻使用者的大脑效应（结构和功能磁共振成像），以及 20 项研究检查了大麻使用起始年龄与成年使用者大脑效应之间的联系。与非使用者相比，青少年大麻使用者的研究主要涉及前额叶和顶叶区域及其与抑制控制、奖励和记忆相关的大脑激活。然而，成人的研究则更加复杂，其中许多研究没有观察到大麻使用起始年龄对大脑影像学指标的影响。虽然有一些证据表明青少年大麻使用会损害额顶叶结构和功能，但仍不清楚观察到的影响是否专门归因于青少年开始使用，还是一般与大麻使用相关的因素，如抑郁症状。青少年大麻使用的起始年龄和使用的慢性程度的相对贡献，将不得不通过更严格的大麻使用措施（剂量、暴露、依赖、组成化合物，如相对大麻素水平）的前瞻性、纵向研究更全面地进行检查。
