Alterations in Brain Structure and Functional Connectivity in Alcohol Dependent Patients and Possible Association with Impulsivity

Abstract

BackgroundPrevious studies have documented that heightened impulsivity likely contributes to the development and maintenance of alcohol use disorders. However, there is still a lack of studies that comprehensively detected the brain changes associated with abnormal impulsivity in alcohol addicts. This study was designed to investigate the alterations in brain structure and functional connectivity associated with abnormal impulsivity in alcohol dependent patients.MethodsBrain structural and functional magnetic resonance imaging data as well as impulsive behavior data were collected from 20 alcohol dependent patients and 20 age- and sex-matched healthy controls respectively. Voxel-based morphometry was used to investigate the differences of grey matter volume, and tract-based spatial statistics was used to detect abnormal white matter regions between alcohol dependent patients and healthy controls. The alterations in resting-state functional connectivity in alcohol dependent patients were examined using selected brain areas with gray matter deficits as seed regions.ResultsCompared with healthy controls, alcohol dependent patients had significantly reduced gray matter volume in the mesocorticolimbic system including the dorsal posterior cingulate cortex, the dorsal anterior cingulate cortex, the medial prefrontal cortex, the orbitofrontal cortex and the putamen, decreased fractional anisotropy in the regions connecting the damaged grey matter areas driven by higher radial diffusivity value in the same areas and decreased resting-state functional connectivity within the reward network. Moreover, the gray matter volume of the left medial prefrontal cortex exhibited negative correlations with various impulse indices.ConclusionsThese findings suggest that chronic alcohol dependence could cause a complex neural changes linked to abnormal impulsivity.

Structural neuroimaging correlates of alcohol and cannabis use in adolescents and adults

“…Negative associations between GM volume and alcohol use were expected among the adult sample, and are consistent with existing literature [4, 59–60]. In adolescents, the cluster of negative association was larger than expected, but did not survive increasing the significance threshold above p <.05.…”

“…Adult alcohol users consistently show lower WM volume and integrity compared to age-matched low- or non-drinkers [1, 17–18, 59], which exceed normal age-related decline [61]. These impairments have been found in widespread brain regions, including frontal and temporal tracts, corticostriatal tracts, and corpus callosum [18–21].…”

Effects of Recreational GHB Use and Multiple GHB-Induced Comas on Brain Structure and Impulsivity

“…Preprocessing of DTI data was conducted with the FMRIB Software Library 5.0.10 (FSL; Analysis Group, FMRIB, Oxford, UK; www.fmrib.ox.ac.uk/fsl) (37). Pre-processing consisted in eddy-current correction of potential distortions induced by gradient coils and head motion artefacts, individual non-brain tissue removal with the brain extraction tool, estimation of the diffusion tensor model at each voxel with the DTIFit tool, generating fractional anisotropy (FA; degree of diffusion directionality), mean diffusivity (MD; average diffusivity rate), axial diffusivity (AD; diffusion rate along the main axis of the tensor), and radial diffusivity (RD; diffusion rate transverse to the main axis of the tensor) scalars (23)(24)(25)38). The diffusion tensor was then assessed for voxel-wise microstructural differences in white matter, at whole-brain with TBSS, or at three a priori defined ROI (tracts) with streamline tractography analysis.…”

“…In a post hoc analysis, we assessed whether group differences in impulsivity were associated with macrostructure or microstructure (DTI indices from TBSS or tractography analyses) data by using a group-by-impulsivity interaction controlled for IQ, cocaine, other stimulants, ecstasy, sedatives, and TIV (19,22,23). Macrostructurally (VBM), when compared with the other two groups, the GHB-Coma group showed a stronger correlation with white matter volume of the posterior SLF ( Table 4 and Figure 2).…”

“…Furthermore, substance use disorders and in particular alcohol-use dependence (another GABAergic dependence), have been associated with substantial alterations in gray matter regions that are often linked to impulse control (i.e., orbitalfrontal cortex, anterior cingulate cortex, medial frontal gyrus, and insula) (19)(20)(21)(22)(23). Moreover, alterations in white matter tracts implicated in reward processing and inhibitory control have been observed in both substance use disorders and conditions involving altered states of consciousness (i.e., inferior frontaloccipital fasciculus, IFOF; inferior longitudinal fasciculus, ILF; uncinate fasciculus, UF; cortical spinal tract, CST; internal capsule, corona radiate, superior longitudinal fasciculus, SLF; cingulum; or corpus callosum, CC) (19,20,(22)(23)(24)(25)(26)(27)(28)(29). Such alterations might be the structural correlate underlying the high levels of impulsivity that are often comorbid with these conditions (2,19,20,(22)(23)(24)(25)30).…”