Structural And Functional Magnetic Resonance Imaging: Application In Ketamine Dependent Subjects And Nicotine Dependent Subjects

Objective:To explore the differences of cognitive function between ketamine users, smokers and healthy controls. Methods:Digit Symbol Test, Trail Making Test and The Stroop Color-Word Test were used to measure the differences of cognitive function in ketamine dependent subjects, smokers and drug free healthy volunteers. Results:compared with smokers and healthy controls, ketamine abuser had significant lower scores in Digit Symbol Test and the Stroop Color-Word Test, but no difference in Trail Making Test. Conclusions:The findings suggest that ketamine abusers have cognitive deficits which supported our finding in neuroimaging studies. However, this test did not show cognitive impairment in chronic cigarette smokers.Objective:To assess the brain white matter integrity in patients with ketamine dependence. Methods:White matter volumes were measured by using in vivo diffusion tensor magnetic resonance imaging (DTI) data in 41ketamine dependent subjects and 44 drug free healthy volunteers. Results: White matter changes associated with chronic ketamine use were found in bilateral frontal and left temporo-parietal cortices. Further, frontal white matter fractional anisotropy (FA) correlated with the severity of drug use (as measured by estimated total ketamine consumption). Conclusions:We provide direct evidence for dose-dependent abnormalities of white matter in bilateral frontal region and left temporo-parietal following chronic ketamine. The findings suggest a microstructural basis for the cognitive changes observed with prolonged ketamine use. Moreover, their similarity to white matter changes observed in chronic schizophrenia have implications for the glutamate model of this illness.Objective:To assess volumetric abnormalities of grey matter in ketamine dependent subjects. Methods:We used voxel based morphometry in conjunction with statistical parametric mapping on the structural magnetic resonance images of ketamine-dependent (n= 41) and drug-naive control individuals (n= 44) to assess differences between the two groups in gray matter volume. Results:We found a decrease in gray matter volume in bilateral frontal (left superior frontal and right middle frontal) cortex of ketamine patients in comparison to controls (p<0.05 corrected for multiple comparisons at cluster-level). Also, we found that the duration (months) of ketamine use was negatively correlated with gray matter volume in bilateral frontal cortex while the estimated total lifetime ketamine consumption was only negatively correlated with gray matter volume in left superior frontal cortex. Conclusions:This is the first voxel-based morphometry study showing reduction of frontal gray matter volume in patients with ketamine dependence and showing the correlation of duration of ketamine use and cumulative doses of ketamine with decrease of frontal gray matter volume. Brian structural study of the affected areas in patients with ketamine dependence might better guide future research into the poorly understood condition of ketamine addiction and its correlates of schizophrenia.Objective:To assess the alterations in regional homogeneity of resting-state brain activity in ketamine dependence. Methods:In this study, 41 patients with ketamine dependence and 44 healthy control subjects being imaged with BOLD fMRI and analyzed with the ReHo method. Results: Compared with healthy controls, decreased ReHo was found in ketamine users in the right Anterior Cingulate and increased ReHo was found in left Frontal Lobe (Precentral Gyrus) (p<0.05, cluster-level corrected). We also observed negative correlations between increased ReHo in precentral frontal gyrus and estimated total lifetime ketamine consumption, ketamine craving. Conclusions:To our knowledge, this is the first time to find the changes of the resting-state of brain activity in patients with ketamine dependence. Our findings indicated abnormal brain activity was distributed frontal cortex in patients with ketamine dependence during resting state.Objective:To assess the Brain white matter integrity in chronic cigarette smokers using diffusion tensor imaging (DTI). Methods:Brain magnetic resonance imaging (MRI) was performed for 44 smokers and 44 healthy age-and sex-matched comparison non-smoking subjects to compare the alteration of white matter integrity as measured by the fractional anisotropy (FA) on diffusion tensor imaging (DTI). Results:DTI data revealed that smokers had higher fractional anisotropy than healthy non-smokers in almost symmetrically bilateral fronto-parietal region white matter. FA differences were not seen in other areas. Positive association between the first start smoking age and increased fractional anisotropy was found in chronic smokers. Conclusions:The data suggest that smokers and non-smokers differed in bilateral fronto-parietal region white matter. These findings support the hypothesis that chronic cigarette smoking involves alterations of bilateral fronto-parietal connectivity and suggest that adolescent cigarette exposure modulates the development of white matter in brain. Objective:To assess volumetric abnormalities of grey matter in chronic cigarette smokers. Methods:We used voxel based morphometry in conjunction with statistical parametric mapping on the structural magnetic resonance images of 44 smokers and 44 non-smoking control individuals to assess gray matter volume differences between the two groups. Results:We found a decrease in gray matter volume in left thalamus, medial frontal cortex and anterior cingulate of smokers in comparison to controls (p<0.001 uncorrected for multiple comparisons at voxel-level). Conclusions:This voxel-based morphometry study showing reduction of regional gray matter volume in smokers. Brian structural study of the affected areas in smokers might better guide future research into the pathogenesis of chronic smoking.Objective:To assess the alterations in regional homogeneity of resting-state brain activity in chronic cigarette smokers. Methods:In this study,45 otherwise healthy smokers and 44 healthy control subjects being imaged with BOLD fMRI and analyzed with the ReHo method. Results: Compared with healthy controls, decreased ReHo was found in smokers in the right inferior frontal gyrus and increased ReHo was found in left superior parietal lobule (p<0.05, voxel=10, cluster-level corrected). Conclusions:To our knowdge, this is the first time to find the changes of the resting-state of brain activity in patients with ketamine dependence. Our findings indicated abnormal brain activity was distributed frontal cortex in patients with ketamine dependence during resting state. Objective:To assess the similarities and differences of cue-induced craving between ketamine user, smokers and healthy controls. Methods: Using block (ketamine-related, smoking-related and sex-related clips) design fMRI to aseess the brain acticities during different cue-induced craving in 41ketamine dependent subjects,45 smokers and 44 drug free healthy volunteers. Results:As for ketamine related cue, ketamine dependent subject showed brain activity changes; there is no difference between smokers and controls. As for smoking related cue, smokers showed higher brain activities than ketamine users and controls. As for sex related cue, ketamine users showed lower brain activity than smokers and controls; there is no difference between smokers and controls. Conclusions:The findings suggest that ketamine and smoking cue-elicited craving induced multiple brain regions' activity which associated with the neurophthology of addiction.