Biomedical subjects

Jaeuk Hwang

Publications and source records attributed to Jaeuk Hwang.

17 recordsLinked to original sources

PubMed2006

Decreased frontal white-matter integrity in abstinent methamphetamine abusers.

This study explored differences in frontal white-matter (WM) integrity between methamphetamine (MA) abusers and healthy comparison subjects using diffusion tensor imaging (DTI). Fractional anisotropy (FA) values, which indicate WM integrity, were calculated for regions-of-interest in frontal WM on diffusion tensor images of 32 MA abusers and 30 healthy comparison subjects. Frontal executive functions were also assessed by the Wisconsin Card Sorting test (WCST). MA abusers had significantly lower FA values in bilateral frontal WM at the anterior commissure-posterior commissure (AC-PC) plane and the right frontal WM 5 mm above the AC-PC plane relative to healthy comparison subjects. MA abusers had more total, perseveration and non-perseveration errors in the WCST relative to healthy comparison subjects. FA values of the right frontal WM 5 mm above the AC-PC plane negatively correlated with the number of total and non-perseveration errors in the WCST in MA abusers. In the sub-analysis for gender differences, lower FA values in frontal WM and more errors in the WCST were found only in male MA abusers, not in female MA abusers, relative to comparison subjects of the respective gender. We report that frontal WM integrity of MA abusers is compromised. This finding may also be related to impairment in frontal executive function. In addition, the neurotoxic effect of MA on frontal WM may be less prominent in women than in men, possibly due to oestrogen's neuroprotective effect.

Adult↗

PubMed2006

Relationship between N-acetyl-aspartate in gray and white matter of abstinent methamphetamine abusers and their history of drug abuse: a proton magnetic resonance spectroscopy study.

OBJECTIVE: Altered concentrations of the brain metabolites, including N-acetyl-aspartate (NAA) and myo-inositol (MI), may indicate neurotoxicity associated with drug abuse. In this study, the authors explored differences in brain metabolites between abstinent methamphetamine (MA) abusers and healthy comparison subjects and the associations between metabolite concentrations and clinical characteristics. METHOD: Proton magnetic resonance spectroscopy (MRS) was performed on 30 abstinent MA abusers and 20 healthy comparison subjects. Two sets of MA user subgroups were defined depending on abstinence duration (greater or less than 6 months) or the total cumulative MA dose (greater or less than 100 g lifetime). NAA and other metabolites were measured in the frontal gray and white matter and compared between MA abuser groups and healthy comparison subjects. RESULTS: MI concentrations were higher for the MA abusers relative to healthy comparison subjects. NAA concentration was lower in frontal white matter of MA abusers with a 'large' cumulative dose relative to those with a 'small' cumulative dose and to healthy comparison subjects. Additionally, in MA abusers NAA concentrations in frontal white matter correlated inversely with the cumulative MA dose. In contrast, there was no significant difference in frontal gray matter NAA concentration among the three groups. However, frontal gray matter NAA concentrations for MA abusers correlated negatively with the total cumulative MA dose and positively with the duration of abstinence. There were no differences between the different MA user groups for MI. CONCLUSIONS: The current findings suggest that MA-induced metabolic alterations of frontal gray and white matter are dose-dependent, for primarily male subjects. Additionally, these findings potentially suggest that the MA-related abnormalities may, in part, recover with abstinence in gray matter, but not in the white matter regions.

Adult↗

PubMed2006

Advances in magnetic resonance imaging methods for the evaluation of bipolar disorder.

This article reviews the current state of magnetic resonance imaging techniques as applied to bipolar disorder. Addressed are conventional methods of structural neuroimaging and recently developed techniques. This latter group comprises volumetric analysis, voxel-based morphometry, the assessment of T2 white matter hyperintensities, shape analysis, cortical surface-based analysis, and diffusion tensor imaging. Structural analysis methods used in magnetic resonance imaging develop exponentially, and now present opportunities to identify disease-specific neuroanatomic alterations. Greater acuity and complementarity in measuring these alterations has led to the generation of further hypotheses regarding the pathophysiology of bipolar disorder. Included in the summary of findings is consideration of a resulting neuroanatomic model. Integrative issues and future directions in this relatively young field, including multi-modal approaches enabling us to produce more comprehensive results, are discussed.

Bipolar Disorder↗

PubMed2006

Basal ganglia shape alterations in bipolar disorder.

OBJECTIVE: Shape differences in the caudate heads and putamen were compared between drug-naive and drug-treated patients with bipolar disorder and healthy comparison subjects by using spherical harmonic (SPHARM) techniques. On the basis of previous studies, the authors hypothesized that the drug-naive patients would exhibit shape differences of the caudate heads and putamen, especially on the right side, relative to the healthy comparison subjects, and that shape differences, relative to healthy comparison subjects, would differ between drug-naive and drug-treated patients. METHOD: Brain magnetic resonance images were acquired from 49 bipolar disorder patients (21 drug-naive and 28 drug-treated patients) and 37 healthy comparison subjects. Volumetric measurements were obtained, and SPHARM descriptions were used to measure between-group radius differences in the surfaces of the caudate heads and putamen. RESULTS: Although no significant between-group volume differences were found in the striatal structures, significant shape differences in the anterior and ventral surfaces of the striatum were observed. Specifically, shape differences, more prominent for the right side, were found for drug-naive bipolar disorder patients, relative to the healthy comparison subjects, but not for drug-treated bipolar disorder subjects. CONCLUSIONS: The findings suggest that drug-naive bipolar disorder patients have shape differences of the striatum, relative to healthy comparison subjects, and that these differences may be modulated by treatment. The findings more generally demonstrate the sensitivity of the SPHARM analytic technique for detecting subtle anatomical shape differences in small brain regions in the absence of volume differences.

Adult↗

PubMed2006

Effects of type 1 diabetes on gray matter density as measured by voxel-based morphometry.

The effects of type 1 diabetes and key metabolic variables on brain structure are not well understood. Sensitive methods of assessing brain structure, such as voxel-based morphometry (VBM), have not previously been used to investigate central nervous system changes in a diabetic population. Using VBM, we compared type 1 diabetic patients aged 25-40 years with disease duration of 15-25 years and minimal diabetes complications with an age-matched, nondiabetic control group. We investigated whether lower than expected gray matter densities were present, and if so, whether they were associated with glycemic control and history of severe hypoglycemic events. In comparison with control subjects, diabetic patients showed lower density of gray matter in several brain regions. Moreover, in the patient group, higher HbA(1c) levels and severe hypoglycemic events were associated with lower density of gray matter in brain regions responsible for language processing and memory. Our study represents the first comprehensive study of gray matter density changes in type 1 diabetes and suggests that persistent hyperglycemia and acute severe hypoglycemia have an impact on brain structure.

Adolescent↗

PubMed2005

Prefrontal and temporal gray matter density decreases in opiate dependence.

RATIONALE: There have been only a few structural brain-imaging studies, with varied findings, of opiate-dependent subjects. Voxel-based morphometry (VBM) is suitable for studying whole brain-wise structural brain changes in opiate-dependent subjects. OBJECTIVES: The objective of the current study is to explore gray matter density in opiate-dependent subjects. METHODS: Gray matter density in 63 opiate-dependent subjects and 46 age- and sex-matched healthy comparison subjects was compared using VBM. RESULTS: Relative to healthy comparison subjects, opiate-dependent subjects exhibited decreased gray matter density in bilateral prefrontal cortex [Brodmann areas (BA) 8, 9, 10, 11, and 47], bilateral insula (BA 13), bilateral superior temporal cortex (BA 21 and 38), left fusiform cortex (BA 37), and right uncus (BA 28). CONCLUSIONS: This study reports that opiate-dependent subjects have gray matter density decreases in prefrontal and temporal cortex, which may be associated with behavioral and neuropsychological dysfunction in opiate-dependent subjects.

Adult↗

PubMed2005

Decreased cerebral blood flow of the right anterior cingulate cortex in long-term and short-term abstinent methamphetamine users.

BACKGROUND: The aim of the current study was to explore changes of relative regional cerebral blood flow (rCBF) in short-term and long-term abstinent methamphetamine (MA) users. METHODS: Relative rCBF in 40 abstinent MA users and 23 healthy comparison subjects was compared by the technetium-99m-hexamethyl-propylene amine oxime ((99m)Tc-HMPAO) single photon emission computed tomography (SPECT). Relative rCBF in areas that were found to differ significantly was also compared in groups of MA users with short-term (<6 months) and long-term (>or=6 months) abstinence. RESULTS: MA users showed decreased relative rCBF in the right anterior cingulate cortex (Brodmann area 32) relative to healthy comparison subjects. Long-term abstinent MA users had significantly greater rCBF than short-term abstinent MA users. CONCLUSIONS: We report that abstinent MA users have decreased rCBF in the anterior cingulate cortex with smaller relative decreases in subjects with prolonged abstinence.

Adult↗

PubMed2005

Decreased blood flow of temporal regions of the brain in subjects with panic disorder.

OBJECT: The purpose of the current study was to investigate alterations of regional cerebral blood flow (rCBF) in subjects with panic disorder. METHODS: Twenty-two subjects with panic disorder who were under psychotropic medications and 25 age and gender-matched healthy comparison subjects were assessed regarding the rCBF of using Tc-99m-hexamethyl propylenamino oxime single photon emission tomography (SPECT). Using statistical parametric mapping, the rCBF was compared between panic disorder and healthy comparison groups. RESULTS: Decreased rCBF flow in right superior temporal lobe was observed in subjects with panic disorder (p<0.05 after correction for multiple comparisons). The rCBF in right superior temporal gyrus negatively correlated with the duration of illness, scores of panic disorder severity scale (PDSS), Hamilton anxiety rating scale (HARS) and Zung self-rating anxiety scale (Z-SAS). CONCLUSION: We report that there is a decreased cerebral blood flow of temporal regions of the brain in panic disorder and that this decrease may, in part, reflect the clinical severity of panic disorder.

Adult↗

PubMed2005

Increased white matter hyperintensities in male methamphetamine abusers.

BACKGROUND: The current study was conducted to compare the prevalence, severity, and location of white matter signal hyperintensities (WMH) on brain magnetic resonance (MR) imaging in methamphetamine (MA) abusers. METHODS: Thirty-three MA abusers and 32 age- and gender-matched healthy comparison subjects were studied. Axial T-2 weighted images and fluid attenuated inversion recovery axial images were obtained using 3.0 T MR scanner. The severity of WMH was assessed separately for deep and periventricular WMH. Ordinal logistic regression models were used to assess the odds ratio for WMH. RESULTS: MA abusers had greater severity of WMH than the healthy comparison subjects (odds ratio: 7.06, 8.46, and 4.56 for all, deep, and periventricular WMH, respectively). Severity of deep WMH correlated with total cumulative dose of MA (p = 0.027). Male MA abusers had greater severity of WMH than female MA abusers (odds ratio = 10.00). While male MA abusers had greater severity of WMH than male comparison subjects (odds ratio = 18.86), there was no significant difference in WMH severity between female MA abusers and female comparison subjects. CONCLUSIONS: The current study reports increased WMH in MA abusers, which may be related to MA-induced cerebral perfusion deficits. In addition, female MA abusers had less severe WMH than male MA abusers, possibly due to estrogen's protective effect against ischemic or neurotoxic effects of MA.

Adult↗

PubMed2005

Prefrontal grey-matter changes in short-term and long-term abstinent methamphetamine abusers.

Authors explored grey-matter density in 29 methamphetamine abusers and 20 healthy comparison subjects using voxel-based morphometry. Grey-matter density changes and performances on the Wisconsin Card Sorting test (WCST) were also compared between 11 short-term (<6 months) and 18 long-term (>or=6 months) abstinent methamphetamine abusers. Methamphetamine abusers had lower grey-matter density in the right middle frontal cortex (corrected p<0.05) and more total errors in the WCST (p<0.01) relative to healthy comparison subjects. Grey-matter density decrease in the right middle frontal cortex correlated with total errors in the WCST in methamphetamine abusers (r=-0.45). Long-term abstinent abusers had significantly less right middle frontal grey-matter density decrease (p<0.01) and total errors in the WCST (p<0.01) than short-term abstinent abusers, but more than the healthy comparison subjects. We report that methamphetamine abusers have prefrontal grey-matter deficit, which may, in part, recover with long-term abstinence.

Adult↗

PubMed2005

Fractional anisotropy-based divisions of midsagittal corpus callosum.

The authors first divided the midsagittal corpus callosum of 22 healthy volunteers using three different subdivision methods: Witelson's geometric subdivision, boundary model-based subdivision, and medial model-based subdivision. Next, subdivisions of the corpus callosum were clustered on the basis of homogeneity of the fractional anisotropy values as produced from diffusion tensor images. Nine subregions of corpus callosum, similar in location and size, were successfully clustered when medial model-based or boundary model-based subdivisions were applied. These nine subregions of the corpus callosum were different from the seven subregions defined by Witelson's geometric subdivision, especially at the anterior and posterior tips of the corpus callosum. Our method of corpus callosum division can be potentially utilized to assess structural changes in the midsagittal corpus callosum.

Adult↗

PubMed2005

Frontal glucose hypometabolism in abstinent methamphetamine users.

Changes in relative regional cerebral glucose metabolism (rCMRglc) and their potential gender differences in abstinent methamphetamine (MA) users were explored. Relative rCMRglc, as measured by (18)F-fluorodeoxyglucose positron emission tomography, and frontal executive functions, as assessed by Wisconsin card sorting test (WCST), were compared between 35 abstinent MA users and 21 healthy comparison subjects. In addition, male and female MA users and their gender-matched comparison subjects were compared to investigate potential gender differences. MA users had lower rCMRglc levels in the right superior frontal white matter and more perseveration and nonperseveration errors in the WCST, relative to healthy comparison subjects. Relative rCMRglc in the frontal white matter correlated with number of errors in the WCST in MA users. In the subanalysis for gender differences, lower rCMRglc in the frontal white matter and more errors in the WCST were found only in male MA users, not in female MA users, relative to their gender-matched comparison subjects. The current findings suggest that MA use causes persistent hypometabolism in the frontal white matter and impairment in frontal executive function. Our findings also suggest that the neurotoxic effect of MA on frontal lobes of the brain might be more prominent in men than in women.

Adult↗

PubMed2004

Trait and state aspects of harm avoidance and its implication for treatment in major depressive disorder, dysthymic disorder, and depressive personality disorder.

The authors evaluated the trait/state issues of harm avoidance in depressive-spectrum disorders and its predictive potential for antidepressant response. Subjects with Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) major depressive disorder (n = 39), dysthymic disorder (n = 37), depressive personality disorder (n = 39), and healthy control subjects (n = 40) were evaluated with the Temperament and Character Inventory and the 17-item Hamilton Depression Rating Scale (HDRS-17) at baseline and after a 12 week antidepressant treatment period. Higher harm avoidance scores predicted lesser improvement in subjects with dysthymic disorder and major depressive disorder, as determined by lesser decrease in HDRS-17 scores. Mean harm avoidance scores in depressed subjects were consistently greater than those in healthy controls, controlling for age, gender and diagnosis. Mean harm avoidance scores decreased significantly in all depressive-spectrum disorders after treatment, but still remained higher than harm avoidance scores in control subjects. The present study reports that harm avoidance is a reliable predictor of antidepressant treatment in subjects with major depressive disorder and dysthymic disorder and that harm avoidance is both trait- and state-dependent in depressive-spectrum disorders.

Adult↗

PubMed2004

Attention deficit hyperactivity symptoms and internet addiction.

The objective of this study was to evaluate the relationship between attention deficit-hyperactivity/impulsivity symptoms and Internet addiction. In total, 535 elementary school students (264 boys, 271 girls; mean age, 11.0 +/- 1.0 years) were recruited. The presence or severity of Internet addiction was assessed by the Young's Internet Addiction test. Parents and teachers of the children completed the DuPaul's attention deficit hyperactivity disorder (ADHD) rating scale (ARS; Korean version, K-ARS) and Child Behavior Checklists. Children with the highest and lowest quartiles in K-ARS scores were defined to be in ADHD and non-ADHD groups, respectively. Five children (0.9%) met criteria for a definite Internet addiction and 75 children (14.0%) met criteria for a probable Internet addiction. K-ARS scores had significant positive correlations with Young's Internet Addiction test scores. The Internet addiction group had higher total scores of K-ARS and ADHD-related subcategories in the Child Behavior Checklists than the non-addiction group. The ADHD group had higher Internet addiction scores compared with the non-ADHD group. Therefore, significant associations have been found between the level of ADHD symptoms and the severity of Internet addiction in children. In addition, current findings suggest that the presence of ADHD symptoms, both in inattention and hyperactivity-impulsivity domains, may be one of the important risk factors for Internet addiction.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

White matter hyperintensities in subjects with bipolar disorder.

There have been divergent reports on the prevalence and severity of white matter hyperintensities (WMH) on brain magnetic resonance (MR) images in subjects with bipolar disorder. In the present study, evaluations were made on the prevalence and severity of WMH in subjects with bipolar disorder using contiguous 3-mm thick MR slices as well as fluid attenuated inversion recovery (FLAIR) images. A detailed WMH rating system was employed to assess these WMH. A total of 43 bipolar patients, as diagnosed by the Structured Clinical Interview from the Diagnostic and Statistical Manual-IV (SCID-IV), and 39 healthy comparison subjects were scanned using a 1.5-T whole body GE magnetic resonance scanner. WMH were assessed with a modified composite version of the Fazekas' and Coffey's rating scales to detect less severe WMH. Periventricular and subcortical WMH were coded separately. Subjects with bipolar disorder had greater prevalence of WMH abnormalities than comparison subjects (Bipolar, grade 1 = 11.6%, grade 2 = 9.3%, grade 3 = 7.0%; Comparison, grade 1 = 5.1%, grade 2 = 2.6%, grade 3 = 0%). This difference is mainly due to the differences in deep WMH (Bipolar, grade 1 = 14.0%, grade 2 = 14.0%; Comparison, grade 1 = 7.7%, grade 2 = 0%). The current study confirms the higher prevalence of WMH in subjects with bipolar disorder. Differences of small-sized WMH abnormalities between groups were successfully detected using a large number of bipolar subjects and thinner sliced MR images with FLAIR.

Adult↗

PubMed2003

Reduced cortical gray matter density in human MDMA (Ecstasy) users: a voxel-based morphometry study.

The popular recreational drug, 3,4-methylenedioxymethamphetamine (MDMA) exerts its actions in part via blockade of serotonin and dopamine reuptake. Many animal and human studies have demonstrated long-lasting reductions in measures of central nervous system (CNS) serotonin function following MDMA administration. One emerging role of serotonin function in the CNS is a positive trophic effect via stimulation of intracellular signaling pathways and trophic factors. We hypothesized that human MDMA users might display neocortical gray matter reductions due to loss of serotonergically mediated trophic effects on cortical cells. However, unlike animal models, most human MDMA users worldwide are polydrug users, thereby complicating the assessment of MDMA toxicity in this group. Structural magnetic resonance imaging (MRI) scans of 31 MDMA polydrug users versus 29 non-MDMA users were compared using voxel-based morphometry (VBM) to assess regional brain gray and white matter concentration. VBM employs gray/white matter segmentation and statistical parametric mapping (SPM) analysis to calculate a voxel-wise comparison of regional gray or white matter concentration. Using this method, we consistently found several brain regions having decreased gray matter concentration in MDMA polydrug users. These regions were localized to neocortex in bilateral Brodmann area (BA) 18, left BA 21, and left BA 45, as well as bilateral cerebellum, and midline brainstem. Overall, these preliminary findings suggest that MDMA polydrug users have multiple regions of gray matter reduction, potentially accounting for previously reported neuropsychiatric impairments in MDMA users. Additional animal model and human studies of the CNS effects of MDMA and combined MDMA-polydrug toxicity are needed to further explain these findings. Potential explanations for our results including pre-existing brain differences predisposing to MDMA polydrug use, direct MDMA and polydrug toxicity, indirect changes due to MDMA and polydrug toxicity, or combinations of all these factors.

Adolescent↗

PubMedDate not supplied

Shape changes of the corpus callosum in abstinent methamphetamine users.

The objective of the current study was to evaluate structural changes of the corpus callosum (CC) in abstinence methamphetamine (MA) users. Shape and size of the CC in 27 MA users were compared to those of 18 healthy comparison subjects. To define the local curvature and width of the CC, medial model-based shape analysis was performed using CC skeletons extracted from a distance map. To define the local displacement of the CC, a boundary model-based shape analysis was performed. In addition, the size of regional areas of the CC was measured according to the Witelson's definition for comparison. In the medial model-based shape analysis, increased curvature in the genu (curvature angle difference = 4.1 degrees) and decreased width in posterior midbody (width difference = 0.77 mm) and isthmus area (width difference = 0.86 mm) of the CC were observed in MA users relative to healthy comparison subjects. In the boundary model-based shape analysis, significant displacement was observed in MA users where there were differences in shape/width patterns by the medial model-based shape analysis. There were no differences in the size of regional areas of the CC between groups. Findings suggest that MA use is associated with regional changes in interhemispheric white matter tracts, which connect frontal and parietal cortices and that these frontal and parietal abnormalities may underlie clinical manifestations of the MA abuse.

Adult↗