Older adults with hardening of the arteries are more likely to have beta-amyloid plaques in their brain even if they have no signs of dementia, according to a University of Pittsburgh study published online today in the journal Neurology.
While researchers still do not know whether amyloid plaques in the brain are the cause or a byproduct of dementia, their presence is associated with and considered the hallmark of Alzheimer’s disease. Arterial stiffness, also known as arteriosclerosis or hardening of the arteries, indicates how hard the heart has to work to pump blood through the body, and is associated with a higher risk of cardiovascular diseases such as stroke and hypertension. Arterial stiffness also affects cerebral blood flow, leading to increased and possibly damaging blood flow in areas of the brain while leaving other areas without enough.
“This research shows more evidence that vascular health and brain health are closely connected,” said study author Timothy M. Hughes, Ph.D., who conducted the research while at the University of Pittsburgh Graduate School of Public Health and is now a senior postdoctoral fellow at Wake Forest School of Medicine. “The findings show that measures of vascular disease, independent of blood pressure, are associated with amyloid deposition in the brain of dementia-free older adults.”
Researchers scanned the brains of 91 individuals aged 83 to 96 who did not have dementia to measure plaque levels in the brain. Two years later, researchers examined the amount of stiffness in the participants’ arteries.
Approximately half of the participants had beta-amyloid plaques in their brains, and were more likely to have high blood pressure and higher arterial stiffness. Furthermore, arterial stiffness was highest in people who had both amyloid plaques and white matter or cerebrovascular lesions, both types of brain lesions.
Each unit of increase in arterial stiffness was associated with a two- to four-fold increase in the odds of having both amyloid plaques and a high amount of brain lesions. According to the authors, individuals with both conditions may therefore be at significantly greater risk of developing dementia. Amyloid imaging studies, using compounds like the Pittsburgh Compound B, also show beta-amyloid deposition is more common than expected in elderly adults.
Previous studies have demonstrated that arterial stiffness is associated with cerebrovascular disease, impaired cognitive function and dementia in the elderly. Recent studies suggest that elevated blood pressure is associated with amyloid deposits in the brain, and that arterial stiffness may be the driving factor. This study is the first to associate arterial stiffness and beta-amyloid deposits in the brain.
“We don’t yet know why amyloid occurs or what the risk factors are. This study adds to the growing research suggesting that arterial stiffness may be more important than current hypertension and both are important potential targets for the prevention of age-related amyloid deposition. Future research will have to tell us if successfully treating hypertension will reduce the beta-amyloid burden in the brains of older adults,” added Hughes.
Co-authors on this paper include Lewis H. Kuller, M.D., Emma J.M. Barinas-Mitchell, Ph.D., Rachel H. Mackey, Ph.D., Eric M. McDade, D.O., William E. Klunk, M.D., Howard J. Aizenstein, M.D., Ph.D., Ann D. Cohen, Ph.D., Beth E. Snitz, Ph.D., Chester A. Mathis, Ph.D., and Oscar L. Lopez, M.D., all of the University of Pittsburgh; and Steven T. DeKosky, M.D., of the University of Virginia.
This study was supported by National Institutes of Health grants AG005133, AG025516, AG025204 and AG000181.