Many of the regions with the earliest atrophy in Alzheimer's Disease (AD) do not show prominent deficits on functional imaging studies of flow or metabolism. This paradox may provide unique insights into the pathophysiology of AD. We sought to examine the relationship between function and atrophy in AD using MRI blood flow and anatomic imaging. 22 subjects diagnosed with AD, mean Mini Mental State Exam (MMSE) score 22.2, and 16 healthy elderly controls were imaged with a volumetric arterial spin labeling blood flow MRI technique and an anatomical imaging method using the identical spatial resolution, image orientation, and spatial encoding strategy. Cerebral blood flow(CBF) and gray matter (GM) maps derived from the imaging were transformed to a standard anatomical space. GM and CBF maps were tested for significant differences between groups. Additionally, images were tested for regions with significant mismatch of the CBF and GM differences between groups. CBF was significantly lower in the bilateral precuneus, parietal association cortex and the left inferior temporal lobe but was non-significantly increased in the hippocampus and other medial temporal structures. After correction for GM loss, CBF was significantly elevated in the hippocampus and other medial temporal structures. The hippocampus and other regions affected early in AD are characterized by elevated atrophy-corrected perfusion per cc of tissue. This suggests compensatory or pathological elevation of neural activity, inflammation, or elevated production of vasodilators.

No abstract

Conditional risk for Posttraumatic Stress Disorder (PTSD)—defined as prevalence, onset, persistence, or severity of PTSD after traumatic exposure—appears to be higher among Latinos relative to non-Latinos after accounting for sociodemographic factors. This systematic review focuses on differences in conditional risk for PTSD between Latinos and non-Latinos (White, Black, or combined) and across Latino subgroups in studies that adjust for trauma exposure. We discuss methodological characteristics of existing articles and sociocultural explanatory factors. Electronic bibliographic searches were conducted for English-language articles published in peer-reviewed journals between 1991 and 2012. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-eight articles met inclusion criteria. Consistent support was found for elevated rates of PTSD onset and PTSD severity among Latinos relative to non-Latino Whites. The evidence on racial/ethnic differences in conditional risk for PTSD prevalence and PTSD persistence is mixed. Twenty-four articles evaluated sociocultural explanations, with the strongest support found for racial/ethnic variation in peritraumatic responses and structure of PTSD. There were also consistent main effects for social disadvantage in studies that simultaneously adjusted for effects of race/ethnicity. Future research should use theoretically-driven models to formally test for interactions between sociocultural factors, race/ethnicity, and PTSD probability.