RESIDUAL COGNITIVE EFFECTS OF CANNABIS--AN FMRI STUDY

尽管大麻被广泛使用，但人们对这种药物对神经认知和神经生理功能的长期影响知之甚少。这项研究来自于我们对大麻对大学生和成人的神经心理影响的研究，以及我们之前利用神经心理学范式和功能磁共振成像（fMRI）来评估区域大脑活动在应对认知挑战时的变化的研究。神经心理学评估表明，大量使用大麻后，某些皮质功能，特别是注意力和记忆处理功能减弱。此外，我们最近对长期吸食大麻的人进行了研究，发现他们在28天的戒断期后，记忆力和注意力的表现仍然明显下降。这些认知缺陷背后的神经机制、这些功能可能恢复的程度以及恢复的时间进程仍有待阐明。到目前为止，还没有研究结合局灶性神经影像学使用认知挑战范式和长时间的监测戒断药物。快速扫描，fMRI技术增加了功能成像的空间和时间，超出了以前的可用性。我们现在提议在1天和28天监测戒断大麻后，在皮质挑战范式中检查三个研究小组的大脑区域激活。这三个研究小组将由60名目前长期重度吸食大麻的人、60名曾经长期重度吸食大麻的人以及60名轻度吸食大麻的人组成。这个项目将提供关于大麻对大脑功能影响的类型、存在和程度的重要新信息。此外，识别出禁欲后认知激活改善的神经过程可能对干预策略的发展、新疗法的设计和公共政策的决策至关重要。

Despite the widespread use of marijuana, relatively little is known about the long term effects of the drug on neurocognitive and neurophysiologic function. The proposed investigation emerges from our studies of neuropsychological effects of marijuana in college students and adults, as well as from our previous investigations utilizing neuropsychological paradigms and functional magnetic resonance imaging (fMRI) to assess changes in regional cerebral activity in response to cognitive challenges. Neuropsychological assessments indicate that selected cortical functions, especially attentional and memory processing, are diminished after heavy cannabis use. Moreover, we have recently studied chronic marijuana smokers after a 28 day abstinence period, and found that performance on measures of memory and attention remained significantly reduced. The neural mechanisms underlying these cognitive deficits, the extent to which these functions may recover, and the time course of recovery remain to be clarified. To date, no study has incorporated focal neuroimaging using cognitive challenge paradigms and a lengthy period of monitored abstinence from the drug. Fast scan, fMRI techniques have increased the spatial and temporal for functional imaging beyond what has previously been available. We now propose to examine regional cerebral activation during cortical challenge paradigms in three study groups following 1 and 28 days of a monitored abstinence from marijuana. The three study groups will be comprised of 60 current heavy long-term smokers of marijuana, 60 former heavy long-term smokers of marijuana, and 60 light smokers of marijuana. This project will provide important new information regarding the type, presence, and magnitude of the effects of cannabis on brain function. Further, the identification of neural processes which demonstrate improvements in cognitive activation following abstinence may be critical for the development of intervention strategies, the design of new treatments, and decisions regarding public policy.