Objective and Methods: Abnormalities of the neuroanatomy of the gray matter of the cingulate gyrus, especially its anterior segment, have been suggested to be an important characteristic of schizophrenia. In this study, T1-weighted magnetic resonance scans were collected in 53 individuals with schizophrenia and 68 comparison subjects matched for age, gender, race and parental socioeconomic status. We applied Labeled Cortical Mantle Distance Mapping to assess the volume, surface and thickness of the cortical mantle within the anterior (AC) and posterior (PC) segments of the cingulate gyrus, excluding the paracingulate gyrus, and related these anatomical measures to measures of psychopathology and illness duration. Results:After covarying for total cerebral volume, individuals with schizophrenia showed smaller AC gray matter volume (p=0.024), thickness (trend, p=0.081), but not surface area (p=0.16), than comparison subjects. Similar group differences were found for PC gray matter volume (p=0.0005) and thickness (trend, p=0.055), but not surface area (p=0.15). Across both groups, there was a significant L>R asymmetry in thickness of the AC, and a significant L>R asymmetry in the surface area of the PC. However, there were no significant group-by-hemisphere interactions. In the individuals with schizophrenia, thinning of the AC, but not the PC, was correlated with a longer duration of illness and a greater severity of psychotic symptoms.Conclusions: Individuals with schizophrenia showed smaller gray matter volumes across the entire cingulate gyrus, mostly due to a reduction in cortical mantle thickness. However, structural measures of the AC were more closely related to clinical features of the illness.

The cingulate gyri in 37 subjects with and without early dementia of the Alzheimer type (DAT) were studied by using MRI at 1.0 mm 3 isotropic resolution. Groups were segregated into young controls (n ‫؍‬ 10), age-matched normal controls (n ‫؍‬ 10), very mild DAT (n ‫؍‬ 8), and mild DAT (n ‫؍‬ 9). By using automated Bayesian segmentation of the cortex and gray matter͞white matter (GM͞WM) isosurface generation, tissue compartments were labeled into gray, white, and cerebrospinal fluid as a function of distance from the GM͞WM isosurface. Cortical mantle distance maps are generated profiling the GM volume and cortical mantle distribution as a function of distance from the cortical surface. Probabilistic tests based on generalizations of Wilcoxon-Mann-Whitney tests were applied to quantify cortical mantle distribution changes with normal and abnormal aging. We find no significant change between young controls and healthy aging as measured by the GM volume and cortical mantle distribution as a function of distance in both anterior and posterior regions of the cingulate. Significant progression of GM loss is seen in the very mild DAT and mild DAT groups in all areas of the cingulate. Posterior regions show both GM volume loss as well as significant cortical mantle distribution decrease with the onset of mild DAT. The ''shape of the cortical mantle'' as measured by the cortical mantle distance profiles manifests a pronounced increase in variability with mild DAT.

Neuropsychiatric disorders have been demonstrated to manifest shape differences in cortical structures. Labeled Cortical Distance Mapping (LCDM) is a powerful tool in quantifying such morphometric differences and characterizes the morphometry of the laminar cortical mantle of cortical structures. Specifically, LCDM data are distances of labeled gray matter (GM) voxels with respect to the gray/white matter cortical surface. Volumes and descriptive measures (such as means and variances for each subject) based on LCDM distances provide descriptive summary information on some of the shape characteristics. However, additional morphometrics are contained in the data and their analysis may provide additional clues to underlying differences in cortical characteristics. To use more of this information, we pool (merge) LCDM distances from subjects in the same group. These pooled distances can help detect morphometric differences between groups, but do not provide information about the locations of such differences in the tissue in question. In this article, we check for the influence of the assumption violations on the analysis of pooled LCDM distances. We demonstrate that the classical parametric tests are robust to the non-normality and within sample dependence of LCDM distances and nonparametric tests are robust to within sample dependence of LCDM distances. We specify the types of alternatives for which the tests are more sensitive. We also show that the pooled LCDM distances provide powerful results for group differences in distribution of LCDM distances. As an illustrative example, we use GM in the ventral medial prefrontal cortex (VMPFC) in subjects with major depressive disorder (MDD), subjects at high risk (HR) of MDD, and healthy subjects. Significant morphometric differences were found in VMPFC due to MDD or being at HR. In particular, the analysis indicated that distances in left and right VMPFCs tend to decrease due to MDD or being at HR, possibly as a result of thinning. The methodology can also be applied to other cortical structures.

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