My reading, specially the book “Connectomics” by Dr Sebastian Seung of MIT, tells me that loss of memory is just not an erasure, but is the gradual loss of our brain’s ability to ‘associate’ and to ‘access’ old memory stores. This can happen due to several reasons, the most salient being a) Loss of charge to below a threshold level for the “Long term memory Neurons” and b) Chemical reasons reducing or weakening the ‘access channels’ to the brain areas associated with long term memory.
I think that, as age advances one should read and reread old classics, novels, poetry and text books, as this helps to reinfornce old memories. Similarly engage in regular review all photo albums of your near and dear, as well as work-related, both paper prints and in digital media.
Religiously solve all puzzles, Sudoku, Crosswords and Mensa Challenges that every Mid-day or Mirror, or Evening or Afternoon papers carry. When on travel, carry puzzle books, riddles, and Sudoku just to exercise your mind/brain.
Learn a new Art or Painting or start writing Fiction or Poetry – just try your hand at it! Or start a new Hobby – Stamp collecting or Gardening – All this starts to strengthen the ‘learning’ associated areas in the brain, and new learning also has to be stored in some fashion, the memory storage areas get refreshed.
Have your own Facebook, Twitter , Whatsapp Group, and other Social media ID and engage in regular social interaction to develop a set of people who will regularly interact with you. This helps to restore Auditory, Visual and experiential memory and most importantly postponse sonset of Senility if not Alzheimers itself!