Brain injuries caused by high blood pressure and stroke are greater risk factors for memory loss and other mental difficulties in seniors than amyloid plaques in the brain that long have been tied to Alzheimer's disease, a new study shows.
Scientists with the Alzheimer's Disease Research Center at the University of California-Davis found hypertension and stroke can damage blood vessels in the brain that lead to cognitive impairments.
The study, published online in the journal JAMA Neurology, indicates such brain injuries are by far the greatest factor that that can affect higher-level thinking and memory.
"The more vascular brain injury the participants had, the worse their memory and the worse their executive function – their ability to organize and problem solve," said Bruce Reed, associate director of the Alzheimer's Disease Research Center.
For the study, researchers tracked 61 Northern California men and women, who ranged in age from 65 to 90 years old, between 2007 and 2012. Thirty of the participants were healthy, 24 had mild cognitive impairments, and seven were diagnosed with dementia.
The study participants underwent magnetic resonance imaging (MRI) ― to measure their vascular brain injury ― and positron emission tomography (PET) scans to measure amyloid plaques in the brain.
The study found that patients with significant evidence of brain injury had bigger problems with memory and executive mental functions than the others. The results also showed the level of amyloid plaques did not impair thinking as much.
Reed said the study is important because there's a growing interest in detecting Alzheimer's disease at its earliest point, before symptoms appear, to speed treatments that can slow its progression.
“The use of [brain scans] will become reasonably widely available within the next couple of years, so doctors will be able to detect whether an older person has abnormal levels of beta amyloid in the brain. So it's very important to understand the meaning of a finding of beta amyloid deposition," Reed said.
"What this study says is that doctors should think about this in a little more complicated way. They should not forget about cerebrovascular disease, which is also very common in this age group and could also cause cognitive problems. Even if a person has amyloid plaques, those plaques may not be the cause of their mild cognitive symptoms."
The new study comes in the wake of other research showing traumatic head injuries and concussions can markedly increase the risk of Alzheimer's disease.
The UC-Davis study was funded, in part, by the National Institutes of Health.
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