The first detailed characterization of the molecular structures of amyloid-beta fibrils that develop in the brains of those with Alzheimer's disease suggests that different molecular structures of amyloid-beta fibrils may distinguish the brains of Alzheimer's patients with different clinical histories and degrees of brain damage.
A new study involving 96 older adults initially free of dementia at the time of enrollment, of whom 12 subsequently developed mild Alzheimer’s, has clarified three fundamental issues about Alzheimer's: where it starts, why it starts there, and how it spreads.
Following on from the evidence that Alzheimer’s brains show higher levels of metals such as iron, copper, and zinc, a mouse study has found that amyloid plaques in Alzheimer’s-like brains with significant neurodegeneration have about 25% more copper than those with little neurodegeneration. This is consistent with a human study showing very high levels of copper in Alzheimer’s plaques.
Iron, though doubled in Alzheimer’s brains compared to controls, was not significantly different as a function of neurodegeneration, and zinc showed very little difference.
Data from 70 older adults (average age 76) in the Baltimore Longitudinal Study of Aging has found that those who reported poorer sleep (shorter sleep duration and lower sleep quality) showed a greater buildup of amyloid-beta plaques.
http://www.eurekalert.org/pub_releases/2013-10/tjnj-lsa101813.php
A new function has been found for the amyloid precursor protein (APP), which may help explain how it goes awry in Alzheimer's disease. It appears that APP (which is involved in the creation of amyloid-beta), also helps control the growth and maturation of newborn brain cells, by regulating a specific microRNA (microRNA-574-5p) that normally promotes neurogenesis.
http://www.eurekalert.org/pub_releases/2014-04/s-nrd041814.php
New research helps explain the role of amyloid-beta plaques in the development of Alzheimer's, by finding that the prion protein known to bind strongly to small aggregates of amyloid-beta peptides, also attaches to large fibrillar clumps of amyloid-beta. However, it doesn’t break them down into smaller, more harmful pieces, as has been suggested. This suggests that prion-protein-based compounds might be a useful means of treatment, to stop these smaller pieces from forming.
Creating amyloid-beta requires the convergence of a protein called amyloid precursor protein (APP) and an enzyme that cleaves APP into smaller toxic fragments (beta-secretase or BACE). Both APP and BACE are common in the brain, so why don’t we all get Alzheimer’s?
A study involving 74 older adults (70+), of whom 3 had mild dementia, 33 were cognitively normal and 38 had mild cognitive impairment, has found that high levels of "good" cholesterol and low levels of "bad" cholesterol correlated with lower levels of the amyloid-beta plaques in the brain (a hallmark of Alzheimer's disease).
http://www.eurekalert.org/pub_releases/2013-12/uoc--hga122613.php
Last year, a cancer drug, Bexarotene, was touted as a potential treatment for Alzheimer’s disease. However, four independent studies have now failed to replicate the most dramatic result of the original study: a claim that the drug could clear half the amyloid plaques in a mere 72 hours.
Still, two of the studies confirmed findings that the drug reduced levels of amyloid-beta, and one showed improved cognition in mice.
The inconsistencies suggest more research is needed. The drug is now being tested in humans.
We know that the E4 variant of the APOE gene greatly increases the risk of developing Alzheimer’s disease, but the reason is a little more mysterious. It has been thought that it makes it easier for amyloid plaques to form because it produces a protein that binds to amyloid beta. However, a new study shows that APOE and amyloid beta don’t bind together in cerebrospinal fluid and in fluids present outside cells grown in dishes, making it unlikely that they are binding together in the brain.