Broyd Samantha J, Greenwood Lisa-marie, van Hell Hendrika H, Croft Rodney J, Coyle Hannah, Lee-Bates Ben, Todd Juanita, Johnstone Stuart J, Michie Patricia T, Solowij Nadia
School of Psychology, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
School of Psychology, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia; Centre for Health Initiatives, University of Wollongong, Wollongong, NSW 2522, Australia.
Neural Plast. 2016;2016:6526437. doi: 10.1155/2016/6526437. Epub 2016 Feb 25.
Prolonged heavy exposure to cannabis is associated with impaired cognition and brain functional and structural alterations. We recently reported attenuated mismatch negativity (MMN) and altered P50 sensory gating in chronic cannabis users. This study investigated the extent of brain functional recovery (indexed by MMN and P50) in chronic users after cessation of use. Eighteen ex-users (median 13.5 years prior regular use; median 3.5 years abstinence) and 18 nonusers completed (1) a multifeature oddball task with duration, frequency, and intensity deviants and (2) a P50 paired-click paradigm. Trend level smaller duration MMN amplitude and larger P50 ratios (indicative of poorer sensory gating) were observed in ex-users compared to controls. Poorer P50 gating correlated with prior duration of cannabis use. Duration of abstinence was positively correlated with duration MMN amplitude, even after controlling for age and duration of cannabis use. Impaired sensory gating and attenuated MMN amplitude tended to persist in ex-users after prolonged cessation of use, suggesting a lack of full recovery. An association with prolonged duration of prior cannabis use may indicate persistent cannabis-related alterations to P50 sensory gating. Greater reductions in MMN amplitude with increasing abstinence (positive correlation) may be related to either self-medication or an accelerated aging process.
长期大量接触大麻与认知功能受损以及大脑功能和结构改变有关。我们最近报告称，慢性大麻使用者的失配负波（MMN）减弱，P50感觉门控改变。本研究调查了慢性使用者停止使用后大脑功能恢复的程度（以MMN和P50为指标）。18名曾经的使用者（之前规律使用的中位数为13.5年；戒断的中位数为3.5年）和18名非使用者完成了（1）一项包含时长、频率和强度偏差的多特征oddball任务，以及（2）一个P50双点击范式。与对照组相比，在曾经的使用者中观察到了趋势水平上较小的时长MMN波幅和较大的P50比率（表明感觉门控较差）。较差的P50门控与之前大麻使用的时长相关。即使在控制了年龄和大麻使用时长之后，戒断时长与时长MMN波幅呈正相关。在长期停止使用后，曾经的使用者中感觉门控受损和MMN波幅减弱的情况往往持续存在，这表明缺乏完全恢复。与之前较长的大麻使用时长相关可能表明P50感觉门控存在持续的大麻相关改变。随着戒断时间增加，MMN波幅更大程度的降低（正相关）可能与自我用药或加速衰老过程有关。
