Yangding Li

Reduced frontal cortical thickness and increased caudate volume within fronto-striatal circuits in young adult smokers

BACKGROUND Smoking during early adulthood results in neurophysiological and brain structural changes that may promote nicotine dependence later in life. Previous studies have revealed the important roles of fronto-striatal circuits in the pathology of nicotine dependence; however, few studies have focused on both cortical thickness and subcortical striatal volume differences between young adult smokers and nonsmokers. METHODS Twenty-seven young male adult smokers and 22 age-, education- and gender-matched nonsmokers were recruited in the present study. The cortical thickness and striatal volume differences of young adult smokers and age-matched nonsmokers were investigated in the present study and then correlated with pack-years and Fagerström Test for Nicotine Dependence (FTND). RESULTS The following results were obtained: (1) young adult smokers showed significant cortical thinning in the frontal cortex (left caudal anterior cingulate cortex (ACC), right lateral orbitofrontal cortex (OFC)), left insula, left middle temporal gyrus, right inferior parietal lobule, and right parahippocampus; (2) in regards to subcortical striatal volume, the volume of the right caudate was larger in young adult smokers than nonsmokers; and (3) the cortical thickness of the right dorsolateral prefrontal cortex (DLPFC) and OFC were associated with nicotine dependence severity (FTND) and cumulative amount of nicotine intake (pack-years) in smokers, respectively. CONCLUSIONS This study revealed reduced frontal cortical thickness and increased caudate volume in the fronto-striatal circuits in young adult smokers compared to nonsmokers. These deficits suggest an imbalance between cognitive control (reduced protection factors) and reward drive behaviours (increased risk factors) associated with nicotine addiction and relapse.

The implication of frontostriatal circuits in young smokers: A resting-state study

The critical roles of frontostriatal circuits had been revealed in addiction. With regard to young smokers, the implication of frontostriatal circuits resting‐state functional connectivity (RSFC) in smoking behaviors and cognitive control deficits remains unclear. In this study, the volume of striatum subsets, i.e., caudate, putamen, and nucleus accumbens, and corresponding RSFC differences were investigated between young smokers (n1 = 60) and nonsmokers (n2 = 60), which were then correlated with cigarette smoking measures, such as pack_years‐cumulative effect of smoking, Fagerström Test for Nicotine Dependence (FTND)‐severity of nicotine addiction, Questionnaire on Smoking Urges (QSU)‐craving state, and Stroop task performances. Additionally, mediation analysis was carried out to test whether the frontostriatal RSFC mediates the relationship between striatum morphometry and cognitive control behaviors in young smokers when applicable. We revealed increased volume of right caudate and reduced RSFC between caudate and dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex in young smokers. Significant positive correlation between right caudate volume and QSU as well as negative correlation between anterior cingulate cortex‐right caudate RSFC and FTND were detected in young smokers. More importantly, DLPFC‐caudate RSFC strength mediated the relationship between caudate volume and incongruent errors during Stroop task in young smokers. Our results demonstrated that young smokers showed abnormal interactions within frontostriatal circuits, which were associated with smoking behaviors and cognitive control impairments. It is hoped that our study focusing on frontostriatal circuits could provide new insights into the neural correlates and potential novel therapeutic targets for treatment of young smokers. Hum Brain Mapp 37:2013–2026, 2016.

Reduced fiber integrity and cognitive control in adolescents with internet gaming disorder

The association between the impaired cognitive control and brain regional abnormalities in Internet gaming disorder (IGD) adolescents had been validated in numerous studies. However, few studies focused on the role of the salience network (SN), which regulates dynamic communication among brain core neurocognitive networks to modulate cognitive control. Seventeen IGD adolescents and 17 healthy controls participated in the study. By combining resting-state functional connectivity and diffusion tensor imaging (DTI) tractography methods, we examined the changes of functional and structural connections within SN in IGD adolescents. The color-word Stroop task was employed to assess the impaired cognitive control in IGD adolescents. Correlation analysis was carried out to investigate the relationship between the neuroimaging indices and behavior performance in IGD adolescents. The impaired cognitive control in IGD was validated by more errors during the incongruent condition in color-word Stroop task. The right SN tract showed the decreased fractional anisotropy (FA) in IGD adolescents, though no significant differences of functional connectivity were detected. Moreover, the FA values of the right SN tract were negatively correlated with the errors during the incongruent condition in IGD adolescents. Our results revealed the disturbed structural connectivity within SN in IGD adolescents, which may be related with impaired cognitive control. It is hoped that the brain-behavior relationship from network perspective may enhance the understanding of IGD.

Abnormal prefrontal cortex resting state functional connectivity and severity of internet gaming disorder

Internet Gaming Disorder (IGD) among adolescents has become an important public concern and gained more and more attention internationally. Recent studies focused on IGD and revealed brain abnormalities in the IGD group, especially the prefrontal cortex (PFC). However, the role of PFC-striatal circuits in pathology of IGD remains unknown. Twenty-five adolescents with IGD and 21 age- and gender-matched healthy controls were recruited in our study. Voxel-based morphometric (VBM) and functional connectivity analysis were employed to investigate the abnormal structural and resting-state properties of several frontal regions in individuals with online gaming addiction. Relative to healthy comparison subjects, IGD subjects showed significant decreased gray matter volume in PFC regions including the bilateral dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC) and the right supplementary motor area (SMA) after controlling for age and gender effects. We chose these regions as the seeding areas for the resting-state analysis and found that IGD subjects showed decreased functional connectivity between several cortical regions and our seeds, including the insula, and temporal and occipital cortices. Moreover, significant decreased functional connectivity between some important subcortical regions, i.e., dorsal striatum, pallidum, and thalamus, and our seeds were found in the IGD group and some of those changes were associated with the severity of IGD. Our results revealed the involvement of several PFC regions and related PFC-striatal circuits in the process of IGD and suggested IGD may share similar neural mechanisms with substance dependence at the circuit level.

Altered resting state functional connectivity of anterior insula in young smokers

The insula has been implicated in cognitive control and craving, all of which are critical to the clinical manifestations of nicotine dependence. However, little evidence exists about the abnormalities in resting state functional connectivity (RSFC) of the insula in young smokers, which might improve our understanding of the neural mechanisms of nicotine dependence. Due to the structural and functional heterogeneity of the insula, the RSFC patterns of both left and right anterior (AI) and posterior insula (PI) were investigated in young smokers and non-smokers. Meanwhile, the relationship was assessed between the neuroimaging findings and clinical information (pack-years, FTND, and craving) as well as cognitive control deficits measured by Stroop task performance. Compared with non-smokers, young smokers showed reduced RSFC between right AI and anterior cingulate cortex (ACC), ventromedial prefrontal cortex (VMPFC), amygdala, left dorsolateral prefrontal cortex, and dorsal striatum. Additionally, left AI showed reduced RSFC with ACC. Both left and right PI network differences were not observed between two groups. Moreover, in young smokers, FTND and incongruent errors in the Stroop task were negatively correlated with the RSFC between AI and ACC. Craving scores showed a significantly negative relationship with the RSFC strength between right AI and left VMPFC. These results provide a more thorough network-level understanding the role of insula in cigarette smoking. The findings provide new insights into the roles of AI-ACC circuit in cognitive control deficits and right AI-VMPFC circuit relevant to the craving of nicotine dependence for young smokers.

Intra-regional and inter-regional abnormalities and cognitive control deficits in young adult smokers

Tobacco use during later adolescence and young adulthood may cause serious neurophysiological changes; rationally, it is extremely important to study the relationship between brain dysfunction and behavioral performances in young adult smokers. Previous resting state studies investigated the neural mechanisms in smokers. Unfortunately, few studies focused on spontaneous activity differences between young adult smokers and nonsmokers from both intra-regional and inter-regional levels, less is known about the association between resting state abnormalities and behavioral deficits. Therefore, we used fractional amplitude of low frequency fluctuation (fALFF) and resting state functional connectivity (RSFC) to investigate the resting state spontaneous activity differences between young adult smokers and nonsmokers. A correlation analysis was carried out to assess the relationship between neuroimaging findings and clinical information (pack-years, cigarette dependence, age of onset and craving score) as well as cognitive control deficits measured by the Stroop task. Consistent with previous addiction findings, our results revealed the resting state abnormalities within frontostriatal circuits, i.e., enhanced spontaneous activity of the caudate and reduced functional strength between the caudate and anterior cingulate cortex (ACC) in young adult smokers. Moreover, the fALFF values of the caudate were correlated with craving and RSFC strength between the caudate and ACC was associated with the cognitive control impairments in young adult smokers. Our findings could lead to a better understanding of intrinsic functional architecture of baseline brain activity in young smokers by providing regional and brain circuit spontaneous neuronal activity properties as well as their association with cognitive control impairments.

Disrupted inter-hemispheric functional and structural coupling in Internet addiction adolescents

Rapid progress had been made towards the effect of Internet addiction (IA) on the adolescents brain, relatively little is known about the alterations in inter-hemispheric resting state functional connectivity (RSFC) changes. In the current study, voxel-mirrored homotopic connectivity (VMHC) was used to examine inter-hemispheric RSFC in IA adolescents (n=21) and controls (n=21). The integrity of the fibers connecting the regions, which showed aberrant inter-hemispheric functional connectivity, was assessed by fiber tractography analysis. In addition, the coupling of inter-hemispheric functional and structural connectivity was investigated. Relative to controls, IA adolescents showed decreased VMHC of dorsolateral prefrontal cortex (DLPFC) and reduced fractional anisotropy (FA) values in the genu of corpus callosum (CC). The decreased VMHC of DLPFC was significantly negative correlated with the duration of IA. Moreover, the VMHC of DLPFC showed significant correlations with the FA of CC in healthy controls, which was disrupted in IA. Our findings provided more scientific evidence for the involvement of DLPFC in IA. It is hoped that multimodal imaging methods can provide deeper insights into the IA effects on the brain.

The implication of salience network abnormalities in young male adult smokers

Studying the neural correlates of smoking behaviors in young adulthood is of great importance to improve treatment outcomes. In previous addiction studies, the important roles of the salience network (SN) in drug cue processing and cognitive control have been revealed. Unfortunately, few studies focused on the resting-state functional connectivity and structural integrity abnormalities of SN in young adult smokers, and less is known about its association with smoking behaviors and cognitive control deficits. Thirty-one young male adult smokers and 30 age-, education- and gender-matched nonsmokers participated in this study. The structural and functional connectivity differences of SN were investigated between young adult smokers and nonsmokers by using diffusion tensor imaging (DTI) and resting-state functional connectivity (RSFC), which were then correlated with the smoking behavioral assessments (pack-years and Fagerström Test for Nicotine Dependence (FTND)) as well as impaired cognitive control measured by the Stroop task. Within SN, reduced RSFC and increased fractional anisotropy (FA) were found between the anterior cingulate cortex (ACC) and the right insula in young adult smokers relative to nonsmokers. The RSFC between the ACC and right insula was negatively correlated with the number of errors during the incongruent condition of the Stroop task in young adult smokers. Additionally, the right insula-ACC RSFC was negatively correlated with pack-years in young adult smokers. Our results revealed abnormal RSFC and structural integrity within the SN in young adult smokers, which shed new insights into the neural mechanism of nicotine dependence.

Neural correlates of 12-h abstinence-induced craving in young adult smokers: a resting-state study

Studying the neural correlates of craving to smoke in young adulthood is of great importance to improve treatment outcomes in nicotine dependence. Previous nicotine dependence studies mainly focused on the neural substrates of craving elicited by smoking-related cues. More explicit attention to abstinence-induced craving during resting state in nicotine dependence has the potential to yield valuable information about craving, and characterizing this kind of craving is critical for developing effective interventions. Twenty-five young male smokers were enrolled in the present study. A within-subject experiment design was carried out to compare regional homogeneity (ReHo) between 12-h smoking abstinence and smoking satiety conditions during resting state in young adult smokers. Then, the ReHo changes associated with smoking abstinence (compared with satiety) were further examined for correlations with abstinence-induced changes in subjective craving. We found young adult smokers in abstinence state (compared with satiety) had higher ReHo in brain regions in fronto-striatal circuits including bilateral caudate, anterior cingulate cortex (ACC) and bilateral dorsal lateral prefrontal cortex (DLPFC), as well as brain regions in default mode network (DMN) including posterior cingulate cortex (PCC)/precuneus and angular gyrus. Additionally, we found the ReHo changes of the ACC and the bilateral caudate were positively correlated with the changes in craving induced by abstinence (i.e., abstinence minus satiety) in young adult smokers. The present findings improve the understanding of the effects of acute smoking abstinence on spontaneous brain activity and may contribute new insights into the neural mechanism of abstinence-induced craving in nicotine dependence.

Functional connectivity abnormalities of brain regions with structural deficits in young adult male smokers

Smoking is one of the most prevalent dependence disorders. Previous studies have detected structural and functional deficits in smokers. However, few studies focused on the changes of resting state functional connectivity (RSFC) of the brain regions with structural deficits in young adult smokers. Twenty-six young adult smokers and 26 well-matched healthy non-smokers participated in our study. Voxel-based morphometry (VBM) and RSFC were employed to investigate the structural and functional changes in young adult smokers. Compared with healthy non-smokers, young smokers showed increased gray matter (GM) volume in the left putamen and decreased GM volume in the left anterior cingulate cortex (ACC). Moreover, GM volume in the left ACC has a negative correlation trend with pack-years and GM volume in the left putamen was positively correlated with pack-years. The left ACC and putamen with abnormal volumes were chosen as the regions of interest (ROIs) for the RSFC analysis. We found that smokers showed increased RSFC between the left ACC and right amygdala and between the left putamen and right anterior insula. We revealed structural and functional deficits within the frontostriatal circuits in young smokers, which may shed new insights into the neural mechanisms of smoking.