Altered brain functional networks in heavy smokers

Abstract

Recent neuroimaging studies have demonstrated that cigarette smoking is associated with changed brain structure and function. However, little is known about alterations of the topological organization of brain functional networks in heavy smokers. Thirty-one heavy smokers and 33 non-smokers underwent a resting-state functional magnetic resonance imaging scan. The whole-brain functional networks were constructed by thresholding the correlation matrices of 90 brain regions and their topological properties were analyzed using graph network analysis. Non-parametric permutation tests were performed to investigate group differences in network topological measures and multiple regression analysis was conducted to determine the relationships between the network metrics and smoking-related variables. Both heavy smokers and non-smokers exhibited small-world architecture in their brain functional networks. Compared with non-smokers, however, heavy smokers showed altered topological measurements characterized by lower global efficiency, higher local efficiency and clustering coefficients and greater path length. Furthermore, heavy smokers demonstrated decreased nodal global efficiency mainly in brain regions within the default mode network, whereas increased nodal local efficiency predominated in the visual-related regions. In addition, heavy smokers exhibited an association between the altered network metrics and the duration of cigarette use or the severity of nicotine dependence. Our results suggest that heavy smokers may have less efficient network architecture in the brain, and chronic cigarette smoking is associated with disruptions in the topological organization of brain networks. Our findings may further the understanding of the effects of chronic cigarette smoking on the brain and the pathophysiological mechanisms underlying nicotine dependence.

Alterations of resting state functional network connectivity in the brain of nicotine and alcohol users

“…Other RSN groups affected by both smoking and drinking were ECN, SAL and PRE indicating the existence of common effects across the brain. These results agree with the detriment of network global efficiency previously observed in both smokers (Fedota and Stein, 2015; Lin et al, 2015) and drinkers (Sjoerds et al, 2015). Few differences were detected when the post-hoc analysis in our data compared rsFNC differences of SAD vs. DRN and SAD vs. SMK groups indicating that common effects cannot differentiate between the substances.…”

Cigarette smoking leads to persistent and dose-dependent alterations of brain activity and connectivity in anterior insula and anterior cingulate

“…We would like to emphasize that we cannot formally exclude a possible alternative explanation that these alterations are a trait of people who smoke, as opposed to people who do not smoke. These connectivity results are in line with a recent study showing decreased connectivity in active smokers versus non-smokers between dorsolateral prefrontal cortex and parietal nodes that are part of the executive control network (ECN) (Weiland et al 2014) and another study which found decreased global efficiency (a measure that takes into account connectivity) in heavy smokers compared with non-smokers (Lin et al 2014). Moreover, our findings are consistent with studies on other forms of addiction, including opioids (Liu et al 2009;Upadhyay et al 2010;Ma et al 2011) and Internet addiction (Hong et al 2013), where a lower functional connectivity is present in addicted subjects.…”

Naltrexone ameliorates functional network abnormalities in alcohol‐dependent individuals

“…A small sample of cocaine‐dependent individuals show reduced local efficiency (Wang et al 2015). However, the opposite pattern has been demonstrated in nicotine dependence, of enhanced local efficiency and reduced global efficiency (Lin et al 2015). Furthermore, a previous study reported no difference in local or global efficiency in heroin dependence (Jiang et al 2013a).…”