Abstract
BackgroundLittle is known about connectivity within the default mode network (DMN) in heroin-dependent individuals (HDIs). In the current study, diffusion-tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) were combined to investigate both structural and functional connectivity within the DMN in HDIs.MethodsFourteen HDIs and 14 controls participated in the study. Structural (path length, tracts count, (fractional anisotropy) FA and (mean diffusivity) MD derived from DTI tractography)and functional (temporal correlation coefficient derived from rs-fMRI) DMN connectivity changes were examined in HDIs. Pearson correlation analysis was performed to compare the structural/functional indices and duration of heroin use/Iowa gambling task(IGT) performance in HDIs.ResultsHDIs had lower FA and higher MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN) to right parahippocampal gyrus (PHG), compared to the controls. HDIs also had decreased FA and track count in the tract connecting the PCC/PCUN and medial prefrontal cortex (MPFC), as well as decreased functional connectivity between the PCC/PCUN and bilateral PHG and MPFC, compared to controls. FA values for the tract connecting PCC/PCUN to the right PHG and connecting PCC/PCUN to the MPFC were negatively correlated to the duration of heroin use. The temporal correlation coefficients between the PCC/PCUN and the MPFC, and the FA values for the tract connecting the PCC/PCUN to the MPFC were positively correlated to IGT performance in HDIs.ConclusionsStructural and functional connectivity within the DMN are both disturbed in HDIs. This disturbance progresses as duration of heroin use increases and is related to deficits in decision making in HDIs.
Highlights
Compulsive drug seeking and use, despite serious negative consequences, characterizes drug addiction [1]
Structural (path length, tracts count, fractional anisotropy (FA) and mean diffusivity (MD) derived from diffusion-tensor imaging (DTI) tractography) and functional default mode network (DMN) connectivity changes were examined in heroin-dependent individuals (HDIs)
FA values for the tract connecting PCC/PCUN to the right parahippocampal gyrus (PHG) and connecting PCC/PCUN to the medial prefrontal cortex (MPFC) were negatively correlated to the duration of heroin use
Summary
Compulsive drug seeking and use, despite serious negative consequences, characterizes drug addiction [1]. Heroin is the most commonly abused illicit substance in China. Approximately 83.3% of illicit drug addicts in China use heroin [2]. In the United States, there are over 1.2 million “occasional” heroin users and over 200,000 people who can be classified as addicted to the drug, according to the National Survey on Drug Use and Health. The investigation of heroin dependent individuals (HDIs) has great potential to improve the understanding of disease pathophysiology. Little is known about connectivity within the default mode network (DMN) in heroin-dependent individuals (HDIs). Diffusion-tensor imaging (DTI) and restingstate functional MRI (rs-fMRI) were combined to investigate both structural and functional connectivity within the DMN in HDIs
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