Hypertension in cognitively normal older adults is correlated with grey matter atrophy in the same brain areas targeted by Alzheimer's disease, according to study data presented on Tuesday at the 2008 meeting of the Radiological Society of North America (RSNA 2008). "This grey matter volume loss persists despite adjusting for multiple covariates such as age, education, head size, and vascular pathologies," reported Cyrus Raji, an MD/PhD candidate at the University of Pittsburgh who conducted the study. (Read the abstract here.) "We also found interaction between hypertension and conversion to mild cognitive impairment (MCI) during the five-year course of the study."

The Cardiovascular Health Study-Cognition Study (CHS-CS) used voxel-based morphometry to analyze grey matter density in 147 cognitively normal adults over age 70, 50 of whom had hypertension (defined as blood pressure of 140/90 or use of anti-hypertension medication). The 1.5T spoiled gradient echo scans were acquired using three-dimensional volumetric MRI, warped into a stereotactic space, and segmented into grey matter, white matter, and cerebrospinal fluid. Each scan was then modulated to convert the tissue density measurements into volume measurements and smoothed into a parametric statistical framework. "One of the benefits of this technology is that we can detect more subtle pathology than by simply looking at the scans visually," Mr. Raji said in an interview with MedicExchange. (Watch the video of the entire interview here)

The hypertension group and control group had no difference in age, gender, or education. Both groups were relatively healthy and showed no difference in vascular disease, white matter hyperintensities, or diabetes. After controlling for all variables, the study found that hypertension was significantly associated with lower grey matter volumes in the hippocampus, posterior cingulate, and precunius, all areas targeted by Alzheimer's disease. Subjects with hypertension who converted to MCI within five years had even lower grey matter volumes than non-hypertensive MCI converters.

The CHS-CS results suggest that future studies of brain atrophy in Alzheimer's disease and aging should control for the atrophying effects of vascular disease. Perhaps of more clinical relevance is the possibility that grey matter atrophy in persons with vascular disease may put them at a higher risk of developing cognitive impairment and dementia. "I believe this presents a pressing public health issue," Mr. Raji told MedicExchange. "If we can better control heart disease, hypertension, obesity, and diabetes, we can potentially improve brain health with aging and remove a huge risk factor for Alzheimer's disease."

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