Dose-related Neurocognitive Effects of Marijuana Use

背景：尽管美国约有700万人每周至少使用一次大麻，但关于大麻使用对神经认知的持续影响的科学数据却很缺乏。目的：确定神经认知缺陷是否在28天戒断重度大麻使用者中持续存在，以及这些缺陷是否与每周吸食大麻关节的数量有关。方法：对戒烟28天的重度大麻滥用者进行一系列神经认知测试。结果：随着每周吸烟量的增加，在记忆力、执行功能、精神运动速度和手灵巧性测试中的表现下降。当将组分为轻度、中度和重度用户组时，重度组在35项测量中的5项上的表现明显低于轻度组，效应大小范围为3.00至4.20 SD单位。使用时间对神经认知表现影响不大。结论：大量使用大麻与神经认知能力持续下降有关，即使在禁欲28天后也是如此。目前还不清楚这些下降是否会随着持续的戒断而消失，还是会随着持续大量使用大麻而逐渐恶化。

BACKGROUND: Although about 7 million people in the US population use marijuana at least weekly, there is a paucity of scientific data on persistent neurocognitive effects of marijuana use. OBJECTIVE: To determine if neurocognitive deficits persist in 28-day abstinent heavy marijuana users and if these deficits are dose-related to the number of marijuana joints smoked per week. METHODS: A battery of neurocognitive tests was given to 28-day abstinent heavy marijuana abusers. RESULTS: As joints smoked per week increased, performance decreased on tests measuring memory, executive functioning, psychomotor speed, and manual dexterity. When dividing the group into light, middle, and heavy user groups, the heavy group performed significantly below the light group on 5 of 35 measures and the size of the effect ranged from 3.00 to 4.20 SD units. Duration of use had little effect on neurocognitive performance. CONCLUSIONS: Very heavy use of marijuana is associated with persistent decrements in neurocognitive performance even after 28 days of abstinence. It is unclear if these decrements will resolve with continued abstinence or become progressively worse with continued heavy marijuana use. These patients were also found significant increases in resistance to flow in the anterior and middle cerebral arteries. It is not know at present if there is a direct correlation between the cognitive changes and the blood flow abnormailities.