This is an amazing and interesting article because it gives insight to why people of the same age might have drastically different health related diseases. Hopefully with further studies of the 150 genes used to understand chronological age can give us greater insight on the causes of Alzheimer's diseases and lead us to discover new ways to possibly treat or prevent the disease. This could also help with finding out reasons why people age biologically more then others.
Link to article: http://www.livescience.com/52105-biological-age-cognitive-health-genes.html
To find out more about Alzheimer's early signs go to: http://www.livescience.com/35611-alzheimers-disease-brain-shrink-early-signs.html