The good doctor is a pharmacologist by training, and her focus at NASA was on the similarities between symptoms of long-term space flight and symptoms of old age. The foreward to her book is by John Glenn. As it turns out, microgravity doesn't make people age. Astronauts and cosmonauts recover when they get back into gravity, and soon return to the shape one would expect of a person that age.
She said what causes the symptoms is the lack of gravity - without gravity, not enough blood gets to the brain, especially during sleep. She did some experiments on volunteers who agreed to be confined to bed for long periods of time, and found the same symptoms.
Balance, she said, is the first thing to go as we age. Yup, old people are unbalanced. :-)
She made a simple recommendation on how to slow down the aging process. Use gravity. Do things which make blood go to your head. Do simple things which exercise your muscles. She said there are lots of suggestions in the book. I'll take a look when the price comes down.