Early to rise
K.E. Pike et al., “Beta-amyloid imaging and memory in non-demented individuals: evidence for preclinical Alzheimer’s disease,” Brain, 130:2837–44, 2007. (Cited in 83 papers)
One of the hallmarks of Alzheimer’s disease (AD) is the build-up of the abnormal peptide ß-amyloid in the brain, although it’s not clear just how amyloid is involved in the disease. To determine whether ß-amyloid levels correlate with memory loss in general, Christopher Rowe at the Austin Hospital in Australia and his colleagues compared the amount of ß-amyloid in normal adults and patients with varying degrees of memory loss. They found that patients with even early signs of memory impairment had higher levels of amyloid than normal adults.
Among patients with established Alzheimer’s disease, those with more memory loss did not have higher levels of amyloid, a finding supported by earlier studies.
The paper “suggests that the amyloid is playing a very early role [in Alzheimer’s],” says lead author Christopher Rowe. Furthermore, the accumulation of amyloid appears to trigger changes in the brain that ultimately result in the cognitive decline, says William Jagust, a neuroscientist at the University of California, Berkeley. Consequently, the time to target amyloid plaques would be the early stages of the disease, perhaps before it is even diagnosed by cognitive tests.
Rowe and his colleagues have initiated a long-term prospective trial to track amyloid and other markers in more than 1,000 people, healthy and with memory decline, as they age.
|Percentage of participants with ß-amyloid plaques:|
|Alzheimer’s disease: 97%|
|Mild cognitive impairment: 61%|
|Healthy aging cases: 22%|