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Background Many studies have revealed a widespread pattern of gray matter (GM) atrophy by using voxel-based morphometry (VBM) studies involving the pathophysiology of alcohol dependence. However, the spatial localization of GM abnormalities reported in previous studies is heterogeneous. Here, we aimed to investigate the concurrence across VBM studies to help clarify the structural abnormalities underpinning this condition. Methods A systematic search from January, 2000 to November, 2014 was performed to identify VBM studies that compared alcohol dependent patients and healthy controls. A quantitative meta-analysis of whole-brain VBM studies to estimate regional GM abnormalities in alcohol dependent patients was performed using the Anisotropic Effect Size version of the Signed Differential Mapping (AES-SDM) software package. Results Nine studies consisting of 296 alcohol dependent patients and 359 healthy controls were included in the present meta-analyses. Regional GM atrophy in alcohol dependent patients was found in the prefrontal cortex (including the anterior cingulate cortex), the dorsal striatum/insula, and the posterior cingulate cortex consistently across studies. The results remained largely unchanged in the following jackknife sensitivity analyses. Conclusions By conducting the first comprehensive meta-analysis of VBM studies, we identified consistent regional GM atrophy particularly within several neurofunctional networks associated with alcohol dependence. Our study demonstrated a characteristic pattern of GM abnormalities and provided further insights into understanding the underlying nature of alcohol dependence.

Background Depressive symptoms are frequent in idiopathic restless legs syndrome (RLS). However, little is known, so far, about the neurological basis. The present study aimed to explore the neuroanatomical anomalies in depressed drug-naive RLS patients using voxel-based morphometry (VBM) analysis. Methods We recruited 16 drug-naive idiopathic RLS patients with depressive symptoms (RLS-D), 18 drug-naive idiopathic RLS patients without depressive symptoms (RLS-ND), and 18 normal controls. All participants underwent structural MRI scans on a 3-T MR system. The differences in regional gray matter (GM) density were determined across groups by VBM8. Additional regression analysis was used to identify any associations between regional GM density and clinical symptoms. Results GM density of the bilateral anterior cingulate cortex (ACC) was significantly reduced in RLS-D patients when compared to RLS-ND patients or to the healthy controls. However, there were no significant differences of GM density either when the whole RLS group or the RLS-ND group was compared to healthy controls, respectively. Particularly, we found GM density of right ACC was negatively correlated with the severity and duration of depressive symptoms in RLS-D patients. Conclusions Depressive symptoms are associated with GM anomalies in ACC in patients with RLS. We propose that ACC is perhaps an important neuroimaging marker for facilitating treatment strategies in patients with RLS when assessing depressive symptoms.

Background : An increasing number of neuroimaging studies have revealed gray matter (GM) anomalies of several brain regions by voxel-based morphometry (VBM) studies in migraineurs. However, not all the studies reported entirely consistent findings. Our aim is to investigate concurrence across VBM studies to help clarify the structural anomalies underpinning this condition. Methods : A systematic search of VBM studies of patients with migraine and healthy controls (HC) published in PubMed and Embase databases from January 2000 to March 2014 was conducted. A quantitative meta-analysis of whole-brain VBM studies in patients with migraine compared with HC was performed by means of anisotropic effect size version of signed differential mapping (AES-SDM) software package. Results : Nine studies comprising 222 patients with migraine and 230 HC subjects were included in the present study. Compared to HC subjects, the patients group showed consistent decreased GM in the posterior insular-opercular regions, the prefrontal cortex, and the anterior cingulate cortex. Results remained largely unchanged in the following jackknife sensitivity analyses. Meta-regression analysis showed that a higher percentage of females in the patient sample was associated with decreased GM in the right dorsolateral prefrontal cortex. Conclusions : This is the first quantitative whole-brain VBM meta-analysis in migraine showing strong evidence of brain GM anomalies within the pain-processing neural network. Further longitudinal investigations are needed to determine whether these structural anomalies are reversible with effective treatment on migraine.

Background Increasing neuroimaging studies have revealed grey matter (GM) anomalies of several brain regions by voxel-based morphometry (VBM) studies in patients with neuropathic pain. The changes have been suggested to be related to central sensitization. Our aim was to investigate concurrence across VBM studies to identify whether different subtypes of neuropathic pain share a common pathophysiological basis revealed by structural abnormalities. Methods A systematic search of VBM studies of patients with neuropathic pain and healthy controls published in PubMed and Embase databases from January 2000 to March 2014 was conducted. A quantitative meta-analysis of whole-brain VBM studies in patients with neuropathic pain compared with healthy controls was performed by means of effect-size signed differential mapping. Results Ten studies comprising 240 patients with neuropathic pain and 263 healthy subjects were systematically included in the present study. Compared to healthy controls, the patients showed consistent decreased GM in bilateral anterior insula and thalamus, right superior frontal gyrus and left postcentral gyrus, and increased GM in right medial frontal gyrus and right posterior insula. The results remained largely unchanged in the following jackknife sensitivity analysis. Conclusions This meta-analysis shows strong evidence of brain GM anomalies within the pain matrix in patients with neuropathic pain compared with healthy subjects. Further studies are needed to determine whether the reported changes are specific to neuropathic pain or whether they may be common to other chronic pain.

Structural neuroimaging studies on chronic smokers using voxel-based morphometry (VBM) had provided cumulative evidence of gray matter (GM) changes relative to nonsmokers. However, not all the studies reported entirely consistent findings. Here, we aimed at identifying consistent GM anomalies in chronic smokers by performing a meta-analysis, and a systematic search of VBM studies on chronic smokers and nonsmokers published in PubMed and Embase database from 2000 to April 2012. Meta-analysis was performed using a newly improved voxel-based meta-analytic tool, namely effect size signed differential mapping, to quantitatively explore the GM abnormalities between chronic smokers and nonsmokers. A total of 7 eligible VBM studies involving 213 chronic smokers and 205 nonsmokers met the inclusion criteria. A considerable regional GM volume decrease was detected in the anterior cingulate cortex (ACC) (BA 24) extending to BA32 in chronic smokers. The findings remain largely unchanged in the entire brain jackknife sensitivity analyses. The results of the present meta-analysis provide evidence of GM changes in ACC in chronic smokers which may be an important potential therapeutic neuro-target for nicotine dependence.