Quantification of the spatiotemporal microstructural organization of the human brain association, projection and commissural pathways across the lifespan using diffusion tensor tractography.

Using diffusion tensor tractography, we quantified the microstructural changes in the association, projection, and commissural compact white matter pathways of the human brain over the lifespan in a cohort of healthy right-handed children and adults aged 6-68 years. In both males and females, the diffusion tensor radial diffusivity of the bilateral arcuate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, corticospinal, somatosensory tracts, and the corpus callosum followed a U-curve with advancing age; fractional anisotropy in the same pathways followed an inverted U-curve. Our study provides useful baseline data for the interpretation of data collected from patients.

Pathways linking socioeconomic position and diabetes: The role of psychosocial factors

Despite increasing interest in the relationship between socioeconomic position (SEP) and health, there remains little understanding of the mechanisms through which SEP is related to chronic disease. This dissertation utilized data from 2,592 U.S. households in the 1995 telephone survey of the Aging, Status, and the Sense of Control study to: (1) investigate potential mediating factors in the association between educational level and prevalence of diabetes and (2) to investigate the association between the three major measures of SEP—income, education, and occupation—and the prevalence of diabetes. Regression analyses were conducted to examine the degree to which sense of personal control and social support mediate the association between level of educational attainment and diabetes and to examine the contribution of each of the SEP measures to diabetes. After adjusting for age, obesity, sex, and race, respondents with less than a high school education had greater odds of having diabetes than those with a college degree or higher level of educational attainment, although the corresponding confidence interval contained the null value (OR = 1.2, 95% CI: 0.7, 2.0). Neither sense of control nor social support significantly mediated the association between education and diabetes. However, sense of control was associated with diabetes status (OR = 0.7, 95% CI: 0.5, 1.0). Compared with income and education, employment status was the most strongly associated measure of SEP with diabetes prevalence. After adjusting for age, obesity, sex, and race, respondents who were unable to work due to disability had fourfold greater odds of having diabetes than those who were employed full time (OR = 4.0; 95% CI: 1.9, 8.3). Adding income and/or education to the model did not improve the fit. Understanding the impact of socioeconomic factors on diabetes requires consideration of multiple measures of SEP as well as the psychosocial pathways through which SEP may influence diabetes. ^