Amyloid plaque linked to arterial stiffness and hypertension

Healthy elderly patients with hardened arteries were up to four times more likely to have amyloid plaque in the brain, according to research published Oct. 16 in Neurology.

Timothy M. Hughes, PhD, with the department of epidemiology at the Graduate School of Public Health at the University of Pittsburgh School of Medicine, and colleagues followed 91 patients with no signs of dementia between the ages of 83 and 96 years to assess cardiovascular measures and amyloid deposition. Results of the study showed that arterial stiffness was related to higher levels of amyloid build-up as well as white matter hyperintensity burden.

“We know high blood pressure is related to Alzheimer’s lesions, dementia and general memory problems, but we are unclear how it does this,” Hughes remarked to Molecular Imaging via an email interview. “As we age, our arteries get stiffer, partly through the effect of hypertension. Our study found that older adults with stiffer arteries have more amyloid deposition in their brain, even though they did not have dementia symptoms. While these people didn’t have Alzheimer’s disease, it appears that the process has started.”

The study included brain MRI and PiB PET imaging of all participants in 2009, followed by an evaluation of arterial stiffness by pulse wave velocity as well as mean arterial pressure and resting blood pressure in 2011. Of the 91 subjects included in the study, 44 tested positive for amyloid plaque following PET scans. A single standard deviation increase in brachial-ankle pulse wave velocity was correlated with double the odds of a positive amyloid PET scan.

The numbers increased when including white matter hyperintensity. Patients with stiffer arteries had a two- to four-fold chance of testing positive for amyloid and white matter hyperintensity burden in the brain. Previous studies have implicated the two to be a "double hit" for the development of dementia.

“I think this study demonstrates that amyloid deposition may be a key, unexpected outcome in studies of ‘normal aging’ and cardiovascular disease,” added Hughes. “If this holds true in younger cohorts, we can expect that hypertension studies will take note and begin to incorporate amyloid imaging into studies of aging with hypertension.”

Further studies need to be conducted to fully understand the association between hypertension and dementia pathology.