Larger corpus callosum and reduced orbitofrontal cortex homotopic connectivity in codeine cough syrup-dependent male adolescents and young adults.

OBJECTIVES: To characterize interhemispheric functional and anatomical connectivity and their relationships with impulsive behaviour in codeine-containing cough syrup (CCS)-dependent male adolescents and young adults. METHODS: We compared volumes of corpus callosum (CC) and its five subregion and voxel-mirrored homotopic functional connectivity (VMHC) in 33 CCS-dependent male adolescents and young adults and 38 healthy controls, group-matched for age, education and smoking status. Barratt impulsiveness scale (BIS.11) was used to assess participant impulsive behaviour. Abnormal CC subregions and VMHC revealed by group comparison were extracted and correlated with impulsive behaviour and duration of CCS use. RESULTS: We found selective increased mid-posterior CC volume in CCS-dependent male adolescents and young adults and detected decreased homotopic interhemispheric functional connectivity of medial orbitofrontal cortex (OFC). Moreover, impairment of VMHC was associated with the impulsive behaviour and correlated with the duration of CCS abuse in CCS-dependent male adolescents and young adults. CONCLUSIONS: These findings reveal CC abnormalities and disruption of interhemispheric homotopic connectivity in CCS-dependent male adolescents and young adults, which provide a novel insight into the impact of interhemispheric disconnectivity on impulsive behaviour in substance addiction pathophysiology. KEY POINTS: • CCS-dependent individuals (patients) had selective increased volumes of mid-posterior corpus callosum • Patients had attenuated interhemispheric homotopic FC (VMHC) of bilateral orbitofrontal cortex • Impairment of VMHC correlated with impulsive behaviour in patients • Impairment of VMHC correlated with the CCS duration in patients.

Aberrant interhemispheric functional and structural connectivity in heroin-dependent individuals.

Models of heroin addiction emphasize the role of disrupted frontostriatal circuitry supporting cognitive control processes. However, heroin addiction-related alterations in functional and structural interactions among brain regions, especially between the cerebral hemispheres, are rarely examined directly. Resting-state functional magnetic resonance imaging (fMRI) approaches, which reveal patterns of coherent spontaneous fluctuations in the fMRI signal, offer a means to quantify directly functional interactions between the hemispheres. The corpus callosum (CC), which connects homologous regions of the cortex, is the major conduit for information transfer between the cerebral hemispheres and represents a structural connectivity index between hemispheres. We compared interhemispheric voxel-mirrored homotopic connectivity (VMHC) and CC volume between 45 heroin dependent-individuals (HDIs) and 35 non-addict individuals. We observed significant reduction of VMHC in a number of regions, particularly the striatum/limbic system regions, and significant decrease in splenium and genu sub-regions of CC in HDI. Importantly, within HDI, VMHC in the dorsal lateral prefrontal cortex (DLPFC) correlated with genu CC volume, VMHC in the putamen, VMHC in the DLPFC and genu CC volume and splenium CC volume were negatively correlated with heroin duration and impulsivity traits. Further analyses demonstrated that impairment of VMHC of bilateral DLPFC partially mediated the association between genu CC volumes decreased and increased impulsivity in HDI. Our results reveal a substantial impairment of interhemispheric coordination in the HDI. Further, interhemispheric connectivity correlated with the duration of heroin abuse and higher impulsivity behavior in HDI. Our findings provide insight into a heroin addicts' related pathophysiology and reinforce an integrative view of the interhemispheric cerebral functional and structural organization.

Potential gray matter unpruned in adolescents and young adults dependent on dextromethorphan-containing cough syrups: evidence from cortical and subcortical study.

Adolescence is a unique period in neurodevelopment. Dextromethorphan (DXM)-containing cough syrups are new addictive drugs used by adolescents and young adults. The effects of chronic DXM abuse on neurodevelopment in adolescents and young adults are still unknown. The aim of this study was to investigate the differences in cortical thickness and subcortical gray matter volumes between DXM-dependent adolescents and young adults and healthy controls, and to explore relationships between alternations in cortical thickness/subcortical volume and DXM duration, initial age of DXM use, as well as impulsive behavior in DXM-dependent adolescents and young adults. Thirty-eight DXM-dependent adolescents and young adults and 18 healthy controls underwent magnetic resonance imaging scanning, and cortical thickness across the continuous cortical surface was compared between the groups. Subcortical volumes were compared on a structure-by-structure basis. DXM-dependent adolescents and young adults exhibited significantly increased cortical thickness in the bilateral precuneus (PreC), left dorsal lateral prefrontal cortex (DLPFC. L), left inferior parietal lobe (IPL. L), right precentral gyrus (PreCG. R), right lateral occipital cortex (LOC. R), right inferior temporal cortex (ITC. R), right lateral orbitofrontal cortex (lOFC. R) and right transverse temporal gyrus (TTG. R) (all p < 0.05, multiple comparison corrected) and increased subcortical volumes of the right thalamus and right pallidum. There was a significant correlation between initial age of DXM use and cortical thickness of the DLPFC. L and PreCG. R. A significant correlation was also found between cortical thickness of the DLPFC. L and impulsive behavior in patients. This was the first study to explore relationships between cortical thickness/subcortical volume and impulsive behavior in adolescents dependent on DXM. These structural changes might explain the neurobiological mechanism of impulsive behavior in adolescent DXM users.

Short-term UROD treatment on cerebral function in codeine-containing cough syrups dependent male individuals.

OBJECTIVE: To investigate alterations of resting brain function in codeine-containing cough syrups (CCS) dependent individuals before and after ultra-rapid opioid detoxification under general anaesthesia (UROD) combined with naltrexone treatment (NMT). METHODS: Fourteen CCS-dependent individuals were scanned using resting-state fMRI. After UROD and 2 weeks of NMT, CCS-dependent individuals were rescanned. Fourteen matched controls were studied at baseline and compared. The amplitude of low frequency fluctuations (ALFF) and seed-based functional connectivity (FC) were used to characterize resting-state cerebral function. RESULTS: After UROD and 2 weeks of NMT, CCS-dependent individuals had increased ALFF in the bilateral parahippocampal gyrus and right medial orbitofrontal cortex (mOFC), decreased ALFF in the left post-central gyrus (PoCG), left middle occipital cortex (MOC) and left dorsal lateral prefrontal cortex (DLPFC), and reduced FC between right mOFC and right DLPFC, and between left DLPFC and left inferior parietal lobe relative to pretreatment. Decreased ALFFs in the left PoCG and left MOC were associated with decreased withdrawal syndrome severity in CCS-dependent individuals. CONCLUSIONS: We offer the first report describing how regional and integral synchronous neural activity occurs after UROD and short-term NMT, accompanied by decreased withdrawal syndrome severity. These findings contribute to the understanding of complex systems involved in UROD-NMT effects. KEY POINTS: • CCS-dependent individuals had reduced ALFF and increased FC at baseline. • UROD treatment can change the regional and integral brain function of CCS-dependent individuals. • Attenuated ALFFs are correlated with the withdrawal syndrome after treatment.

Reduced ventral medial prefrontal cortex (vmPFC) volume and impaired vmPFC-default mode network integration in codeine-containing cough syrups users.

OBJECTIVE: To characterize the association between clinical symptoms and anatomical and functional cerebral deficits in codeine-containing cough syrups (CCS) users using voxel-based morphometry and resting state functional connectivity analysis. METHODS: Participants were 30 CCS users and 30 matched controls. Both groups were scanned using a volumetric three-dimensional fast field echo sequence and a gradient-echo echo-planar imaging sequence. Impulsivity traits of both groups were evaluated with the Barratt Impulsiveness Scale 11 (BIS 11). Voxel-based morphometry was used to characterize gray matter (GM) deficits in CCS users. The clinical significance of regional volume reduction was investigated by evaluating its association with impulsivity in CCS users and with alterations in resting state functional connectivity when brain regions with GM volume reduction were used as seed areas. RESULTS: Significantly decreased GM volume was observed in CCS users in bilateral ventral medial prefrontal cortex (vmPFC) which was related to greater impulsivity in CCS users. Significantly decreased integration was found in CCS users between the vmPFC and the default mode network. Also, significantly enhanced functional connectivity was found between the vmPFC and the right insula, and the right dorsal lateral PFC. Negative correlation was observed between BIS total scores, scores for attentional impulsivity and vmPFC-inferior parietal lobe connectivity in CCS users. CONCLUSIONS: The findings revealed volume loss and aberrant functional organization in vmPFC among CCS users. In addition, the decreased vmPFC GM volume and attenuated functional connectivity of the vmPFC-inferior parietal lobe network were associated with clinical higher impulsivity trait in CCS users.

The impulsivity behavior is correlated with prefrontal cortex gray matter volume reduction in heroin-dependent individuals.

PURPOSE: Chronic exposure to heroin induced cerebral structural abnormalities may underlie heroin-related behaviors. The aim of this study was to: (1) identify cerebral structural abnormalities in heroin-dependent individuals (HDIs) by an automated and unbiased morphometric technique. (2) Define the correlation between these cerebral structural abnormalities and the impulsivity characteristic in HDIs. METHODS: 24 HDIs and 24 control subjects were completed with (1) high resolution structural magnetic resonance imaging scanning and analysis of gray matter volume using voxel-based morphometry implemented in Statistical Parametric Mapping and (2) a Chinese translation Barratt Impulsiveness Scale-11 questionnaire survey. Differences in regional gray matter volume were tested using an analysis of covariance model, co-varying for global gray matter and age. Statistical maps were set at p<0.05, corrected for multiple comparisons. The abnormal brain regions were correlated with the duration of heroin use and impulsivity scores. RESULTS: After adjusting for effects of age and total gray matter volume, cortical gray matter volume in the bilateral medial prefrontal cortex, bilateral dorsal lateral prefrontal cortex, and right fusiform cortex were significantly reduced in HDIs. Moreover, the gray matter volume in prefrontal cortex that showed group differences was negatively correlated with the duration of heroin use and negatively correlated with the impulsivity characteristic in HDIs. CONCLUSION: These findings reveal the prefrontal cortex was impaired in HDIs, meanwhile, indicate the changes in gray matter volume are relating to the duration of heroin use and the impulsivity characteristic of the HDIs.

Regional homogeneity changes in heroin-dependent individuals: resting-state functional MR imaging study.

PURPOSE: To identify heroin-related modulations of neural activity in the resting state in heroin-dependent individuals (HDIs) by using resting-state functional magnetic resonance (MR) imaging and a regional homogeneity method and to investigate whether these changes of neural activity can be related to duration of heroin use and to decision-making deficits in HDIs. MATERIALS AND METHODS: This prospective study was approved by the appropriate ethics committee, and written informed consent was obtained from each participant. Thirty-one HDIs receiving methadone-maintained treatment and 24 control subjects participated. Resting-state functional MR imaging was performed by using a gradient-echo echo-planar imaging sequence. Regional homogeneity was calculated by using software. Voxel-based analysis of the regional homogeneity maps between control and HDI groups was performed with two-sample t tests by using software. Statistical maps were set at P less than .05 and were corrected for multiple comparisons. The Iowa gambling task (IGT) was used to assess participant decision making during uncertainty. Abnormal clusters revealed by group comparison were extracted and correlated with behavioral performance at the IGT and with duration of heroin use. RESULTS: Regional homogeneity was diminished in the bilateral medial orbitofrontal cortex (OFC), bilateral dorsal medial thalamus, bilateral cuneus, and lingual gyrus in HDIs compared with control subjects. There were negative correlations between mean regional homogeneity in the medial OFC, bilateral cuneus, and lingual gyrus and duration of heroin use. There was a positive correlation between mean regional homogeneity in the medial OFC and performance level at the IGT. CONCLUSION: The present study reveals resting-state abnormalities in HDIs that may lead to further improvement of the understanding of the neural substrates of cognitive impairment in HDIs.

Amplitude low-frequency oscillation abnormalities in the heroin users: a resting state fMRI study.

Functional neuroimaging studies have revealed abnormal functional organization of the heroin users' brain, including reward circuit, cognitive control circuit, memory circuit, motivation and salience evaluation circuits and so on. In the current study, we aimed to explore the functional changes in the regional brain of heroin users using the amplitude of low-frequency oscillations in the Blood Oxygenation Level Dependent (BOLD) signals. With fMRI data acquired during resting state from 24 chronic heroin users (all subjects were being treated with methadone) and 24 non-addicted controls, we investigated addiction related altered in the amplitude low-frequency fluctuate (ALFF) between the two groups. Compared with controls, we found that heroin addicts had decreased ALFF in the bilateral dorsal anterior cingulate cortex (dACC), bilateral medial orbit frontal cortex (mOFC), left dorsal lateral prefrontal cortex (dlPFC), left middle temporal gyrus, left inferior temporal gyrus, posterior cingulate cortex and left cuneus as well as increased ALFF in the bilateral angular gyrus, bilateral precuneus, bilateral supramarginal gyrus, left post cingulate cortex and left middle frontal gyrus. Moreover, we also found that the increased ALFF in the bilateral parietal lobe had a significantly positive correlation with the methadone does, thus we inferred that the reduced ALFF may due to heroin consumption, nevertheless, the increased ALFF in the bilateral parietal lobe may have resulted from the methadone treatment. This resting-state fMRI study suggests that the changed spontaneous neuronal activity of these regions may be implicated in the underlying pathophysiology of heroin addicts.