Complicating Alzheimer's Disease
From MedPage Today: "The pathological features of Alzheimer's disease -- tangles, neuritic plaques, and diffuse plaques -- may not be as representative of clinical dementia in the very old as in the younger elderly ... For example, a 75-year-old with a moderate-to-severe burden of neurofibrillary tangles in the hippocampus was much more likely to have had a dementia diagnosis than a 95-year-old with the same amount of tangles. ... it will become even more important to understand the atypical cases of older old persons who are cognitively intact despite having neurodegenerative-disease lesions. ... their findings suggest that current disease-based classifications made on the basis of discrete entities, such as Alzheimer's disease, vascular dementia, or mixed dementia, are [a] simplification." One thing that leaps to mind here is that a 95-year-old is much less likely than a 75-year-old to have been overweight and suffered metabolic syndrome (by virtue of having avoided death by all the age-related conditions that follow that state) - and Alzheimer's appears to be very much like diabetes in terms of its relationship to metabolism and excess fat.
Link: http://www.medpagetoday.com/Geriatrics/AlzheimersDisease/14400