Background: Structural brain damage, especially to white matter, is well documented in chronic alcohol abuse. There is also evidence for brain metabolic abnormalities in this condition. It is ...unknown, however, to what extent these structural and metabolic changes are present in treated alcohol abusers who achieve long‐term abstinence versus treatment‐naïve, heavily drinking individuals.
Methods: This study compared 12 recovering alcoholics with 8 actively heavily drinking subjects. Participants underwent magnetic resonance (MR) imaging and proton MR spectroscopic imaging of the brain. Semiautomated image segmentation techniques yielded volumes for gray matter, white matter, white matter lesions, and cerebral spinal fluid in multiple brain regions defined by Talairach stereotaxic coordinates. Automated spectral processing methods yielded gray and white matter concentrations of the metabolites N‐acetylaspartate, creatine, and choline for the same regions.
Results: Recovering alcoholics had greater volumes of frontal white matter, but the opposite was true for white matter in a “remainder” region encompassing the basal frontal and temporal lobes, the cerebellum, and the brainstem. Recovering alcoholics also had smaller volumes of white matter lesions in whole brain, in occipital and mesial parietal regions, and in the remainder region. Recovering alcoholics had greater gray matter volumes in the orbital frontal pole and postcentral gyrus, but smaller gray matter volumes in the anterior cingulate. Whole‐brain and regional metabolite concentrations did not differ significantly between the two groups.
Conclusions: White and gray matter volumes in different regions of the brain were greater or smaller in recovering, treated alcoholics. The findings suggest region‐specific structural recovery from chronic alcohol–induced brain injury, but also region‐specific long‐term structural damage in abstinent alcoholics. White matter lesions were widespread in active drinkers and may partly resolve during long‐term abstinence. Proton MR spectroscopic measures, as applied in this cross‐sectional study, were largely ineffective in revealing metabolic effects of abstinence on the alcohol‐damaged brain.
ABSTRACT
BACKGROUND AND PURPOSE
To determine if a voxel‐wise “co‐analysis” of structural and diffusion tensor magnetic resonance imaging (MRI) together reveals additional brain regions affected in ...mild cognitive impairment (MCI) and Alzheimer's disease (AD) than voxel‐wise analysis of the individual MRI modalities alone.
METHODS
Twenty‐one patients with MCI, 21 patients with AD, and 21 cognitively normal healthy elderly were studied with MRI. Maps of deformation and fractional anisotropy (FA) were computed and used as dependent variables in univariate and multivariate statistical models.
RESULTS
Univariate voxel‐wise analysis of macrostructural changes in MCI showed atrophy in the right anterior temporal lobe, left posterior parietal/precuneus region, WM adjacent to the cingulate gyrus, and dorsolateral prefrontal regions, consistent with prior research. Univariate voxel‐wise analysis of microstructural changes in MCI showed reduced FA in the left posterior parietal region extending into the corpus callosum, consistent with previous work. The multivariate analysis, which provides more information than univariate tests when structural and FA measures are correlated, revealed additional MCI‐related changes in corpus callosum and temporal lobe.
CONCLUSION
These results suggest that in corpus callosum and temporal regions macro‐ and microstructural variations in MCI can be congruent, providing potentially new insight into the mechanisms of brain tissue degeneration.
Alcoholism is characterized by a lack of control over excessive alcohol consumption despite significant negative consequences. This impulsive and compulsive behavior may be related to functional ...abnormalities within networks of brain regions responsible for how we make decisions. The abnormalities may result in strengthened networks related to appetitive drive-or the need to fulfill desires-and simultaneously weakened networks that exercise control over behaviors. Studies using functional magnetic resonance imaging (fMRI) in abstinent alcoholics suggest that abstinence is associated with changes in the tone of such networks, decreasing resting tone in appetitive drive networks, and increasing resting tone in inhibitory control networks to support continued abstinence. Identifying electroencephalographic (EEG) measures of resting tone in these networks initially identified using fMRI, and establishing in longitudinal studies that these abstinence-related changes in network tone are progressive would motivate treatment initiatives to facilitate these changes in network tone, thereby supporting successful ongoing abstinence.
A previous study (Haley RW, Marshall WW, McDonald GG, Daugherty MA, Petty F, Fleckenstein JL: Brain abnormalities in Gulf War syndrome: evaluation with 1H MR spectroscopy. Radiology 2000; 215: ...807-817) suggested that individuals with Gulf War Illness (GWI) had reduced quantities of the neuronal marker N-acetylaspartate (NAA) in the basal ganglia and pons. This study aimed to determine whether NAA is reduced in these regions and to investigate correlations with other possible causes of GWI, such as psychological response to stress in a large cohort of Gulf War veterans. Individuals underwent tests to determine their physical and psychological health and to identify veterans with (n=81) and without (n=97) GWI. When concentrations of NAA and ratios of NAA to creatine- and choline-containing metabolites were measured in the basal ganglia and pons, no significant differences were found between veterans with or without GWI, suggesting that GWI is not associated with reduced NAA in these regions. Veterans with GWI had significantly higher rates of post-traumatic stress disorder, supporting the idea that GWI symptoms are stress related.
Abstract Alcohol use disorders (AUD) and chronic cigarette smoking are common among individuals with human immunodeficiency virus infection (HIV). Concurrent AUD in HIV is related to greater ...abnormalities in brain morphology and neurocognition than either condition alone. However, the potential influence of chronic smoking on brain morphology and neurocognition in those concurrently afflicted with AUD and HIV has not been examined. The goal of this retrospective analysis was to determine if chronic smoking affected neurocognition and brain morphology in a subsample of HIV-positive non–treatment-seeking heavy drinking participants (HD+) from our earlier work. Regional volumetric and neurocognitive comparisons were made among age-equivalent smoking HD+( n = 17), nonsmoking HD+ ( n = 27), and nonsmoking HIV-negative light drinking controls ( n = 27) obtained from our original larger sample. Comprehensive neuropsychological assessment evaluated multiple neurocognitive domains of functioning and for potential psychiatric comorbidities. Quantitative volumetric measures of neocortical gray matter (GM), white matter (WM), subcortical structures, and sulcal and ventricular cerebral spinal fluid (CSF) were derived from high-resolution magnetic resonance images. The main findings were (1) smoking HD+ performed significantly worse than nonsmoking HD+ on measures of auditory-verbal (AV) learning, AV memory, and cognitive efficiency; (2) relative to controls, smoking HD+ demonstrated significantly lower neocortical GM volumes in all lobes except the occipital lobe, while nonsmoking HD+ showed only lower frontal GM volume compared with controls; (3) in the HD+ group, regional brain volumes and neurocognition were not influenced by viremia, highly active antiretroviral treatment, or Center for Disease Control symptom status, and no interactions were apparent with these variables or smoking status. Overall, the findings suggested that the direct and/or indirect effects of chronic cigarette smoking created an additional burden on the integrity of brain neurobiology and neurocognition in this cohort of HIV-positive heavy drinkers.
Background: Previous MRI studies of bipolar disorder have failed to consistently demonstrate cortical gray or cerebral white matter tissue loss, as well as sulcal or ventricular enlargement. The ...inconsistencies are most likely due to the clinical and gender heterogeneity of the study populations as well as the different MRI acquisition and processing techniques. The objective of this study was to determine if there was a cortical gray matter and cerebral white matter deficit as well as sulcal and ventricular enlargement in a homogeneous sample of euthymic male patients with familial bipolar I disorder.
Methods: MRI tissue segmentation was utilized to obtain cortical gray matter, cerebral white matter, ventricular cerebrospinal fluid (CSF), and sulcal CSF volumes in 22 euthymic males with familial bipolar I disorder and 32 healthy male control subjects.
Results: Relative to the controls, the familial bipolar I patients demonstrated: (1) significant reductions of both cortical gray matter and cerebral white matter volumes; and (2) significant increases in both sulcal and ventricular CSF volumes. In the bipolar group, there was a significant negative correlation between cortical gray matter volume and sulcal CSF volume.
Limitations: Small sample size, retrospective interviews, possible medication effects.
Conclusions: These results provide evidence for significant cortical gray matter and cerebral white matter deficits and associated sulcal and ventricular enlargement in euthymic males with familial bipolar I disorder.
Summary
Purpose: The thalamus plays an important role in seizure propagation in temporal lobe epilepsy (TLE). This study investigated how structural abnormalities in the focus, ipsilateral thalamus ...and extrafocal cortical structures relate to each other in TLE with mesiotemporal sclerosis (TLE‐MTS) and without hippocampal sclerosis (TLE‐no).
Methods: T1 and high‐resolution T2 images were acquired on a 4T magnet in 29 controls, 15 TLE‐MTS cases, and 14 TLE‐no. Thalamus volumes were obtained by warping a labeled atlas onto each subject’s brain. Deformation‐based morphometry was used to identify regions of thalamic volume loss and FreeSurfer for cortical thickness measurements. CA1 volumes were obtained from high‐resolution T2 images. Multiple regression analysis and correlation analyses for voxel‐ and vertex‐based analyses were performed in SPM2 and FreeSurfer.
Results: TLE‐MTS had bilateral volume loss in the anterior thalamus, which was correlated with CA1 volume and cortical thinning in the mesiotemporal lobe. TLE‐no had less severe volume loss in the dorsal lateral nucleus, which was correlated with thinning in the mesiotemporal region but not with extratemporal thinning.
Discussion: The findings suggest that seizure propagation from the presumed epileptogenic focus or regions close to it into the thalamus occurs in TLE‐MTS and TLE‐no and results in circumscribed neuronal loss in the thalamus. However, seizure spread beyond the thalamus seems not to be responsible for the extensive extratemporal cortical abnormalities in TLE.
This paper is motivated by the analysis of serial structural magnetic resonance imaging (MRI) data of the brain to map patterns of local tissue volume loss or gain over time, using registration-based ...deformation tensor morphometry. Specifically, we address the important confound of local tissue contrast changes which can be induced by neurodegenerative or neurodevelopmental processes. These not only modify apparent tissue volume, but also modify tissue integrity and its resulting MRI contrast parameters. In order to address this confound we derive an approach to the voxel-wise optimization of regional mutual information (RMI) and use this to drive a viscous fluid deformation model between images in a symmetric registration process. A quantitative evaluation of the method when compared to earlier approaches is included using both synthetic data and clinical imaging data. Results show a significant reduction in errors when tissue contrast changes locally between acquisitions. Finally, examples of applying the technique to map different patterns of atrophy rate in different neurodegenerative conditions is included.
Before using MRI tissue segmentation in clinical studies as a dependent variable or as a means to correct functional data for differential tissue contribution, we must first establish the volume ...reliability and spatial distribution reproducibility of the segmentation method. Although several reports of volume reliability can be found in the literature, there are no articles assessing the reproducibility of the spatial distribution of tissue. In this report, we examine the validity, volume reliability, and spatial distribution reproducibility for our K-means cluster segmentation. Validation was examined by classifying gray matter, white matter, and CSF on images constructed using an MRI simulator and digital brain phantom, with percentage volume differences of less than 5% and spatial distribution overlaps greater than 0.94 (1.0 is perfect). We also segmented repeat scan MRIs from 10 healthy subjects, with intraclass correlation coefficients greater than 0.92 for cortical gray matter, white matter, sulcal CSF, and ventricular CSF. The original scans were also coregistered to the repeat scan of the same subject, and the spatial overlap for each tissue was then computed. Our overlaps ranged from 0.75 to 0.86 for these tissues. Our results support the use of K-means cluster segmentation, and the use of segmented structural MRIs to guide the analysis of functional and other images.
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