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Biomedical subjects

R Momenan

Publications and source records attributed to R Momenan.

9 recordsLinked to original sources
PubMed2001

Negative association of neuroticism with brain volume ratio in healthy humans.

BACKGROUND: Brain volume decreases with normal aging. We sought to determine whether, in addition to age, individual differences in stress reactivity (i.e., neuroticism) would also predict reductions in brain volume. METHODS: Brain volume ratios were calculated for a sample of 86 healthy volunteers, based on segmented brain volumes taken from T(1)-weighted magnetic resonance imaging and corrected for intracranial volume. Standardized self-reported measures of dispositional neuroticism were concurrently obtained by administering the Revised NEO Personality Inventory. RESULTS: After statistically controlling for age and sex, neuroticism showed a significant negative association with the ratio of brain to the remainder of the intracranial volume, but was not related to intracranial volume itself. In particular, subfactors of neuroticism related to the chronic experience of arousing negative emotions were associated with reduced brain ratio. CONCLUSIONS: These results suggest that individual differences in stress reactivity contribute to reductions in brain volume observed during adulthood.

Adult↗
PubMed2001

Neuroimaging in alcoholism: ethanol and brain damage.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The co-chairs were Karl Mann and Ingrid Agartz. The presentations were (1) Neuropathological changes in alcohol-related brain damage, by Clive Harper; (2) Regional brain volumes including the hippocampus and monoamine metabolites in alcohol dependence, by Ingrid Agartz, Susan Shoaf, Robert R, Rawlings, Reza Momenan, and Daniel W Hommer; (3) Diffusion tensor abnormalities in imaging of white matter alcoholism, by Adolf Pfefferbaum and Edith V. Sullivan; (4) Use of functional MRI to evaluate brain activity during alcohol cue exposure in alcoholics: Relationship to craving, by Raymond F. Anton, David J. Drobes, and Mark S. George; and (5) mu-Opiate receptor availability in alcoholism: First results from a positron emission tomography study, by Karl Mann, Roland Bares, Hans-Juergen Machulla, Goetz Mundle, Matthias Reimold, and Andreas Heinz.

Alcoholism↗
PubMed2001

Evidence for a gender-related effect of alcoholism on brain volumes.

OBJECTIVE: The goal of this study was to compare brain volumes of alcoholic and nonalcoholic men and women and determine if the magnitudes of differences in brain volumes between alcoholic women and nonalcoholic women are greater than the magnitudes of the differences between alcoholic men and nonalcoholic men. METHOD: The study group included 118 subjects: 79 inpatients 30-60 years of age who were alcohol dependent but had no clinically apparent cognitive impairment or medical illness (43 men and 36 women) and 39 healthy comparison subjects of similar age who were not alcoholic (20 men and 19 women). The volume of intracranial contents was segmented into gray matter, white matter, sulcal CSF, and ventricular CSF from a T(1)-weighted magnetic resonance image obtained after the alcoholic subjects had attained 3 weeks of sobriety. RESULTS: Alcoholic women had significantly smaller volumes of gray and white matter as well as greater volumes of sulcal and ventricular CSF than nonalcoholic women. The differences in gray and white matter volumes between alcoholic and nonalcoholic men were significant, but the significance of these differences was of a smaller magnitude than the significance of the differences between alcoholic and nonalcoholic women. Direct comparisons of alcoholic men and women showed that the proportion of intracranial contents occupied by gray matter was smaller in alcoholic women than in alcoholic men. The magnitudes of differences in brain volumes adjusted for intracranial size between alcoholic women and nonalcoholic women were greater than the magnitudes of the adjusted differences between alcoholic men and nonalcoholic men. CONCLUSIONS: These results are consistent with greater sensitivity to alcohol neurotoxicity among women.

Adult↗
PubMed1999

Hippocampal volume in patients with alcohol dependence.

BACKGROUND: Smaller hippocampal volumes have been reported in the brains of alcoholic patients than in those of healthy subjects, although it is unclear if the hippocampus is disproportionally smaller than the brain as a whole. There is evidence that alcoholic women are more susceptible than alcoholic men to liver and cardiac damage from alcohol. It is not known whether the hippocampi of the female brain are more vulnerable to alcohol. METHODS: We compared the hippocampal volumes in 52 hospitalized alcoholic men and women with those of 36 healthy nonalcoholic men and women. All subjects were between 27 and 53 years of age. The hippocampal volumes were measured from sagittal T-weighted high-resolution magnetic resonance images. RESULTS: The alcoholic women had less lifetime drinking and a later age at onset of heavy drinking than alcoholic men. Both alcoholic men and women had significantly smaller right hippocampi and larger cerebrospinal fluid volumes than healthy subjects of the same sex. Only among women were the left hippocampus and the nonhippocampal brain volume also significantly smaller. The proportion of hippocampal volume relative to the rest of the brain volume was the same in alcoholic patients and healthy subjects, in both men and women. The right hippocampus was larger than the left among all subjects. Women demonstrated larger hippocampal volumes relative to total brain volume than men. Psychiatric comorbidity, including posttraumatic stress disorder, did not affect hippocampal volume. CONCLUSIONS: In chronic alcoholism, the reduction of hippocampal volume is proportional to the reduction of the brain volume. Alcohol consumption should be accounted for in studies of hippocampal damage.

Adult↗
PubMed1997

Effects of m-chlorophenylpiperazine on regional brain glucose utilization: a positron emission tomographic comparison of alcoholic and control subjects.

m-Chlorophenylpiperazine (mCPP) is a mixed serotonin agonist/antagonist used extensively in psychiatric research. Alcoholics show blunted neuroendocrine responses to mCPP, and in some settings mCPP can induce craving for alcohol, particularly among early onset alcoholics. We used 2-[18F]-2-deoxy-D-glucose positron emission tomography to examine the effects of intravenously administered mCPP (0.08 mg/kg) on brain glucose utilization in a group of 18 male alcoholics and 12 healthy male control subjects. Differences between two sequential scans (the first followed placebo and the second followed mCPP) were evaluated statistically with a Gaussian random field-based method. Among healthy volunteers mCPP significantly increased brain glucose metabolism in the right medial and posterior orbital gyrus, the cerebellar hemispheres bilaterally, the left nucleus accumbens, the head of the caudate nucleus bilaterally, the anterior and medial-dorsal nuclei of the thalamus bilaterally, the middle frontal gyrus, the left insular cortex, the left middle temporal gyrus, and the posterior cingulate gyrus. Among alcoholic subjects mCPP significantly increased brain glucose metabolism in larger areas of the cerebellum and posterior cingulate than it did in healthy volunteers, but compared with the healthy volunteers, alcoholics showed a smaller area of mCPP-induced activation in the thalamus, almost no activation in the orbital cortices, and no activation at all in the head of the caudate nucleus or the middle frontal gyrus. These results suggest that a serotoninergic challenge activates basal ganglia circuits involving orbital and prefrontal cortices among healthy volunteers but that the response of these circuits is blunted among alcoholics.

Adult↗
PubMed1996

Decreased corpus callosum size among alcoholic women.

BACKGROUND: Although females appear to be more sensitive to the hepatic consequences of alcoholism, it is not clear if women are more sensitive to the effects of excessive alcohol consumption on the brain than men. SUBJECTS AND METHODS: We compared the cross-sectional area of the corpus callosum in a group of 14 hospitalized alcoholic women and 13 hospitalized alcoholic men with a group of nine nonalcoholic women and 10 nonalcoholic men. All subjects were between the ages of 30 and 50 years. The cross-sectional areas of the corpus callosum and the inner table of the skull were measured on midsagittal T1-weighted magnetic resonance images. RESULTS: Females had smaller intracranial areas than males, but there was no difference in intracranial area between the alcoholics and nonalcoholics. The corpus callosum area was significantly smaller among the alcoholic women compared with either the control women or the alcoholic men. Alcoholic men did not differ from control men in the corpus callosum area. These results did not change when the corpus callosum area was adjusted for intracranial area by analysis of covariance. When the corpus callosum was divided into four segments of equal length, the reduction in area was not localized to any particular region. CONCLUSION: These results suggest an increased sensitivity to alcohol-induced brain damage among alcoholic women compared with alcoholic men.

Adult↗
PubMed1996

Statistical methods in the Fourier domain to enhance and classify images.

A mathematical model, for which rigorous methods of statistical inference are available, is described and techniques for image enhancement and linear discriminant analysis of groups are developed. Since the gray values of neighboring pixels in tomographically produced medical images are spatially correlated, the calculations are carried out in the Fourier domain to insure statistical independence of the variables. Furthermore, to increase the power of statistical tests the known spatial covariance was used to specify constraints in the spectral domain. These methods were compared to statistical procedures carried out in the spatial domain. Positron emission tomography (PET) images of alcoholics with organic brain disorders were compared by these techniques to age-matched normal volunteers. Although these techniques are employed to analyze group characteristics of functional images, they provide a comprehensive set of mathematical and statistical procedures in the spectral domain that can also be applied to images of other modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI).

Aged↗
PubMed1986

Pattern recognition methods for optimizing multivariate tissue signatures in diagnostic ultrasound.

Described is a supervised parametric approach to the detection and classification of disease from acoustic data. Statistical pattern recognition techniques are implemented to design the best ultrasonic tissue signature from a set of measurements and for a given task, and to rate its performance in a way that can be compared with other diagnostic tools. In this paper, we considered combinations of four ultrasonic tissue parameters to discriminate, in vivo, between normal liver and chronic active hepatitis. The separation between normal and diseased samples was made by application of the Bayes decision rule for minimum risk which includes the prior probability for the presence of disease and the cost of misclassification. Large differences in classification performance of various tissue parameter combinations were demonstrated using the Hotelling trace criterion (HTC) and receiver operating characteristic (ROC) analysis. The ability of additional measurements to increase or decrease discriminability, even measurements from other diagnostic modalities, can be evaluated directly in this manner.

Humans↗