There will be a remarkable increase in the number of people older than 85 years—the oldest-old—in the next 50 years. This age group is especially vulnerable to increasing disabilities, many of which are the result of the aging nervous system. Among these aging changes, the most devastating and likely to have the greatest impact on our society is the development of dementia. Since dementia is present in the majority of those who live to the current maximum of the human life span, this suggests that dementia is a normal aging event. Although the exact causes of this common cognitive failure in the oldest-old are not known, there is recent evidence from genetic studies of aging and Alzheimer disease to suggest that there are a number of susceptibility genes that may modify or delay the onset of late-life brain failure. These gene families form a natural target for devising strategies for significantly delaying the onset of late-life dementia.
Kaye JA. Oldest-Old Healthy Brain FunctionThe Genomic Potential. Arch Neurol. 1997;54(10):1217-1221. doi:10.1001/archneur.1997.00550220027009