Shen Zhujing, Huang Peiyu, Qian Wei, Wang Chao, Yu Hualiang, Yang Yihong, Zhang Minming
Department of Radiology, the Second Affiliated Hospital, Zhejiang University School of Medicine, No. 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China.
Department of Psychiatry, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Psychopharmacology (Berl). 2016 Jun;233(11):2129-2137. doi: 10.1007/s00213-016-4262-5. Epub 2016 Mar 9.
Nicotine dependence is characterized as a neural circuit dysfunction, particularly with regard to the reward circuit. Although dependence severity moderates cue reactivity in the brain regions involved in reward processing, the direction of its influence remains controversial.
Investigating the functional organization of the reward circuit may provide complementary information. Here, we used resting-state functional connectivity (rsFC) to evaluate the integrity of the reward circuit in smokers with different severities of nicotine dependence.
Totals of 65 smokers and 37 non-smokers underwent resting-state functional magnetic resonance imaging (fMRI). The smokers were divided into low-dependent (FTND < 5, n = 26) and high-dependent smoker groups (FTND ≥ 5, n = 39) based on their nicotine-dependence severity (as measured by the Fagerström test for nicotine dependence [FTND]). The region of interest (ROI)-wise rsFC within the reward circuit was compared between smokers and non-smokers as well as between low-dependent and high-dependent smokers and then correlated with smokers' FTND scores.
Widespread rsFC attenuation was observed in the reward circuit of smokers compared with non-smokers. Compared with low-dependent smokers, high-dependent smokers showed greater rsFC between the right amygdala and the left nucleus accumbens (NAcc) as well as between the bilateral hippocampus. Furthermore, a positive correlation between the inter-hippocampus rsFC and the severity of nicotine dependence (FTND) was detected among all smokers (r = 0.416, p = 0.001).
Our results indicate a dysfunction of the reward circuit in nicotine-dependent individuals. Moreover, our study improves the understanding of the neuroplastic changes that occur during the development of nicotine dependence.
尼古丁依赖的特征是神经回路功能障碍，尤其是在奖赏回路方面。尽管依赖严重程度会调节参与奖赏处理的脑区中的线索反应性，但其影响方向仍存在争议。
研究奖赏回路的功能组织可能会提供补充信息。在此，我们使用静息态功能连接（rsFC）来评估不同尼古丁依赖严重程度的吸烟者奖赏回路的完整性。
65名吸烟者和37名非吸烟者接受了静息态功能磁共振成像（fMRI）。根据吸烟者的尼古丁依赖严重程度（通过尼古丁依赖的法格斯特罗姆测试[FTND]测量），将他们分为低依赖组（FTND＜5，n = 26）和高依赖组（FTND≥5，n = 39）。比较吸烟者与非吸烟者之间以及低依赖与高依赖吸烟者之间奖赏回路内感兴趣区域（ROI）的rsFC，然后将其与吸烟者的FTND分数相关联。
与非吸烟者相比，吸烟者的奖赏回路中观察到广泛的rsFC减弱。与低依赖吸烟者相比，高依赖吸烟者在右侧杏仁核与左侧伏隔核（NAcc）之间以及双侧海马体之间表现出更大的rsFC。此外，在所有吸烟者中检测到海马体间rsFC与尼古丁依赖严重程度（FTND）之间呈正相关（r = 0.416，p = 0.001）。
我们的结果表明尼古丁依赖个体的奖赏回路存在功能障碍。此外，我们的研究增进了对尼古丁依赖发展过程中发生的神经可塑性变化的理解。
