Amyloid Plaques May Not Necessarily Come First in Alzheimer's Disease, Suggests New Study

A study in Neurology challenges the theory that beta-amyloid plaques in the brain are the first manifestation of Alzheimer's disease, reports News-Medical . The researchers imply that subtle thinking and memory differences may precede or occur parallel to amyloid plaque accrual, as participants who exhibited these differences had faster amyloid accumulation on brain scans over time. One test that uses a dye to measure amyloid levels, where the average level was 1.16 for participants with subtle thinking and memory difficulties, found levels in that cohort rose by 0.03 above and beyond the levels in those with normal thinking and memory skills over four years. Those cohort members also had faster thinning of the entorhinal cortex, a brain area that is affected very early in Alzheimer's. However, although participants with mild cognitive impairment had more amyloid in their brains at the start of the study, they did not have faster amyloid buildup compared to those with normal thinking and memory skills — but they did exhibit faster thinning of the entorhinal cortex and shrinkage of the hippocampus. "Our study demonstrated a method to successfully detect subtle differences in thinking and memory either before or during the phase when amyloid is accumulating at a faster rate," said VA San Diego Healthcare System's Kelsey R. Thomas. "This could lead to non-invasive screenings that may be able to detect very early who is at risk of developing Alzheimer's disease."