A study in the JAMA Neurology (formerly the Archives of Neurology) suggests that controlling or preventing risk factors such as hypertension earlier in life may limit or delay the brain changes associated with Alzheimer's disease and other age-related neurological deterioration.
Dr. Karen Rodrigue, assistant professor in the UT Dallas Center for Vital Longevity (CVL), was lead author on a study that looked at whether people with both hypertension and a common gene associated with risk of Alzheimer's disease (the APOE-4 gene carried by about 20 percent of the population) had more buildup of the brain plaque (amyloid protein) associated with Alzheimer's disease. Many scientists believe the amyloid plaque is the first symptom of Alzheimer's disease and shows up a decade or more before Alzheimer's symptoms of memory impairment and other cognitive difficulties begin.
Until recently, amyloid plaque could only be seen at autopsy, but new brain scanning techniques allow scientists to see the amyloid plaque in living brains of healthy adults. Findings from both autopsy and amyloid brain scans show that at least 20 percent of normal older adults carry elevated levels of amyloid, a substance made up mostly of protein and deposited in organs and tissues.
"I became interested in whether hypertension was related to increased risk of amyloid plaques in the brains of otherwise healthy people," Rodrigue said. "Identifying the most significant risk factors for amyloid deposition in seemingly healthy adults will be critical in advancing medical efforts aimed at prevention and early detection."
Based on evidence that hypertension was associated with Alzheimer's disease, Rodrigue suspected that the double-whammy of hypertension and presence of the APOE-e4 gene might lead to particularly high levels of amyloid plaque in healthy adults.
Rodrigue's research was part of the Dallas Lifespan Brain Study, a comprehensive study of the aging brain in a large group of adults of all ages funded by the National Institute on Aging. As part of this study, the research team recruited 147 participants (ages 30-89) to undergo cognitive testing, magnetic resonance imaging (MRI) and PET imaging, using Amyvid, a compound that when injected travels to the brain and binds with amyloid proteins, allowing the scientists to visualize the amount of amyloid plaque. Blood pressure was measured at each visit.
Rodrigue classified participants in the study as hypertensive if they reported a current physician diagnosis of hypertension or if their blood pressure exceeded the established criteria for diagnosis. The participants were further divided between individuals who were taking anti-hypertensive medications and those who were not medicated, but showed blood pressure elevations consistent with a diagnosis of hypertension. Finally, study subjects were classified in the genetic risk group if they were in the 20 percent of adults who had one or two copies of an APOE å4 allele, a genetic variation linked to dementia.
The most striking result of the study was that unmedicated hypertensive adults who also carried a genetic risk factor for Alzheimer's disease, showed much higher amyloid levels than all other groups. Adults taking hypertensive medications, even those with genetic risk, had levels of amyloid plaque equivalent to participants without hypertension or genetic risk.
The study suggests that controlling hypertension may significantly decrease the risk of developing amyloid deposits, even in those with genetic risk, in healthy middle-aged and older adults. Rodrigue noted that long-term studies of many people were needed to be certain that it was the use of hypertensive medications that was causal of the decreased amyloid deposits. Nevertheless, this early finding provides a window into the potential benefits of controlling hypertension that goes beyond decreasing risk of strokes and other cardiovascular complications.
Scientists cannot fully explain the neural mechanisms underlying the effect of hypertension and APOE å4 on amyloid accumulation. But earlier research in animal models showed that chronic hypertension may enable easier penetration of the blood-brain barrier, resulting in more amyloid deposition.
The recent study is significant because it focuses on a group of healthy and cognitively normal middle-aged and older adults, which enables the examination of risk factors and amyloid burden before the development of preclinical dementia. The team plans for long-term longitudinal follow-up with participants to determine which proportion of the subjects eventually develop the disease.
The study's coauthors included Dr. Denise Park, director of the Dallas Lifespan Brain Study, and Dr. Kristen Kennedy and doctoral student Jennifer Rieck, all from The University of Texas at Dallas. The team also included Dr. Michael Devous and Dr. Ramon Diaz-Arrastia, scientists from UT Southwestern Medical Center and the Uniformed Services University of the Health Sciences. In addition to the National Institute on Aging, the Alzheimer's Association provided funds for the study. Avid Radiopharmaceutical provided doses of Amyvid that allowed the researchers to image the amyloid plaque with a PET scan.
Emily Martinez | EurekAlert!
Satellites, airport visibility readings shed light on troops' exposure to air pollution
09.12.2016 | Veterans Affairs Research Communications
Oxygen can wake up dormant bacteria for antibiotic attacks
08.12.2016 | Penn State
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine