Differences In Total Brain Volume Research Articles

Postmenopausal hormone therapy and regional brain volumes

To determine whether menopausal hormone therapy (HT) affects regional brain volumes, including hippocampal and frontal regions. Brain MRI scans were obtained in a subset of 1,403 women aged 71-89 years who participated in the Women's Health Initiative Memory Study (WHIMS). WHIMS was an ancillary study to the Women's Health Initiative, which consisted of two randomized, placebo-controlled trials: 0.625 mg conjugated equine estrogens (CEE) with or without 2.5 mg medroxyprogesterone acetate (MPA) in one daily tablet. Scans were performed, on average, 3.0 years post-trial for the CEE + MPA trial and 1.4 years post-trial for the CEE-Alone trial; average on-trial follow-up intervals were 4.0 years for CEE + MPA and 5.6 years for CEE-Alone. Total brain, ventricular, hippocampal, and frontal lobe volumes, adjusted for age, clinic site, estimated intracranial volume, and dementia risk factors, were the main outcome variables. Compared with placebo, covariate-adjusted mean frontal lobe volume was 2.37 cm(3) lower among women assigned to HT (p = 0.004), mean hippocampal volume was slightly (0.10 cm(3)) lower (p = 0.05), and differences in total brain volume approached significance (p = 0.07). Results were similar for CEE + MPA and CEE-Alone. HT-associated reductions in hippocampal volumes were greatest in women with the lowest baseline Modified Mini-Mental State Examination scores (scores <90). Conjugated equine estrogens with or without MPA are associated with greater brain atrophy among women aged 65 years and older; however, the adverse effects are most evident in women experiencing cognitive deficits before initiating hormone therapy.

Association of Alcohol Consumption With Brain Volume in the Framingham Study

While adults who drink low to moderate amounts of alcohol have lower rates of cardiovascular disease than other adults, the effect of alcohol on the brain is less clear. There is evidence that drinking large amounts of alcohol is related to brain atrophy. It is uncertain what the effects of low to moderate consumption might be. To determine whether consumption of smaller amounts of alcohol negatively affects brain volume or is protective in reducing the well-documented age-related decline in brain volume. Total cerebral brain volume (TCBV) was computed, correcting for head size. Multivariate linear regression models were used to evaluate the association between 5 categories of alcohol consumption (abstainers, former drinkers, low, moderate, high) and TCBV, adjusting for age, sex, education, height, body mass index (calculated as weight in kilograms divided by height in meters squared), and the Framingham Stroke Risk Profile. Pairwise comparisons were also conducted between the alcohol consumption groups. A total of 1839 subjects from the Framingham Offspring Study who had magnetic resonance imaging of the brain between 1999 and 2001. Most participants reported low alcohol consumption, and men were more likely than women to be moderate or heavy drinkers. There was a significant negative linear relationship between alcohol consumption and TCBV (r = -0.25; P < .001). This relationship was modified by sex, with alcohol consumption having a stronger association with TCBV in women than in men (r = -0.29 vs -0.20). In contrast to studies on cardiovascular disease, this study found that moderate alcohol consumption was not protective against normal age-related differences in total brain volume. Rather, the more alcohol consumed, the smaller the total brain volume.

The human inferior parietal lobule in stereotaxic space

Recently, a new cytoarchitectonic map of the human inferior parietal lobule (IPL) has been proposed, with the IPL consisting of seven cytoarchitectonically distinct areas (Caspers et al. in Neuroimage 33(2):430-448, 2006). The aim of the present study was to investigate the different aspects of variability of these IPL areas. As one aspect of variability, we analysed the topographical relationship between the localisation of the borders of the areas and macroanatomical landmarks. Although five areas occupy the surface supramarginal gyrus and two the angular gyrus, their borders cannot be reliably detected by means of macroanatomy. To account for variability in size and extent of the areas in stereotaxic space, cytoarchitectonic probabilistic maps have been calculated for each IPL area. Hemisphere- and gender-related differences have been investigated on basis of volumes of cytoarchitectonic areas. For one of them, area PFcm, a significant gender difference in volume was found with males having larger volumes than females; this difference exceeds that of gender differences in total brain volume. The different aspects of variability and volumetric asymmetry may underlie some of the well-known functional asymmetries in the IPL, observed, for example during fMRI experiments analysing spatial attention or motor attention, and planning. The cytoarchitectonic probabilistic maps of the seven IPL areas provide a robust anatomical reference and open new perspectives for further structure-function investigations of the human IPL.

Hippocampus and Amygdala Volumes in Parents of Children With Autistic Disorder

Structural and functional abnormalities in the medial temporal lobe, particularly the hippocampus and amygdala, have been described in people with autism. The authors hypothesized that parents of children with a diagnosis of autistic disorder would show similar changes in these structures. Magnetic resonance imaging scans were performed in 17 biological parents of children with a diagnosis of DSM-IV autistic disorder. The scans were compared with scans from 15 adults with autistic disorder and 17 age-matched comparison subjects with no personal or familial history of autism. The volumes of the hippocampus, amygdala, and total brain were measured in all participants. The volume of the left hippocampus was larger in both the parents of children with autistic disorder and the adults with autistic disorder, relative to the comparison subjects. The hippocampus was significantly larger in the adults with autistic disorder than in the parents of children with autistic disorder. The left amygdala was smaller in the adults with autistic disorder, relative to the other two groups. No differences in total brain volume were observed between the three groups. The finding of larger hippocampal volume in autism is suggestive of abnormal early neurodevelopmental processes but is partly consistent with only one prior study and contradicts the findings of several others. The finding of larger hippocampal volume for the parental group suggests a potential genetic basis for hippocampal abnormalities in autism.

ADHD and Conduct Disorder: An MRI Study in a Community Sample

Summary: MRI studies of children with Attention-Deficit Hyperactivity Disorder (ADHD) have consistently attributed core deficits of inattention and impulsivity to frontal-striatal-cerebellar abnormalities; however, no study has investigated the neuroanatomical characteristics of children with ADHD and Conduct Disorder (CD). This study examined a community sample of 12 children with combined subtype ADHD (aged 8-12, 7 with CD) and 19 healthy controls matched for age, gender, handedness and poverty. Volume measurements, including left/right asymmetries, were quantified from MRI of the total brain, caudate and cerebellar vermis. No significant differences in total brain volume, caudate volume, asymmetry of the hemispheres or asymmetry of the caudate were found between the groups. Measurements of the left and total posterior superior and inferior lobes of the vermis, however, indicated smaller volumes for both pure ADHD and co-morbid children compared to the controls. Analysis of variance demonstrated no significant volumetric differences between the pure ADHD and co-morbid types. Prolonged exposure to methylphenidate was associated with caudate volumes. These results suggest ADHD and ADHD co-morbid with CD have similar deviant cerebellar morphology and replicate previous studies with an epidemiologically derived sample.

Testosterone is correlated with regional morphology of the human corpus callosum

Theoretical speculation in humans (S.F. Witelson, Psychoneuroendocrinology 16 (1991) 131–153) and empirical findings in animals (R.H. Fitch, P.E. Cowell, L.M. Schrott, V.H. Denenberg, Int. J. Dev. Neurosci. 9 (1991) 35–38) suggest that testosterone (T) may play a significant role in the development of the corpus callosum (CC). However, there are currently no empirical studies directly relating T concentrations to callosal morphology in humans. The purpose of the present study was to investigate the relationship between free T concentrations as determined by radioimmunoassay, and the mid-sagittal area of the corpus callosum, as determined by magnetic resonance imaging (MRI). Subjects were 68 young adult (20–35 years), neurologically normal, right-handed males. All subjects underwent MRI and provided two samples of saliva for radioimmunoassay of T and cortisol. Anatomical regions of interest included total brain volume, left and right hemisphere volume and regional areas of the CC. CC regions were defined using two different measurement techniques, each dividing the CC into six sub-sections. Anatomical measurements were performed blind with respect to the hormone levels of subjects. A significant positive correlation between T concentration and cross-sectional area of the posterior body of the CC was found. This finding was consistent across the two measurement techniques and was not attributable to individual differences in total brain volume. All correlations between cortisol and CC sub-regions were non-significant. The results of this study are consistent with the notion that T, at an earlier stage in development, may play a significant role in modulating cortical/callosal architecture in humans.