The time it would take to see the improvement cannot easily be predicted. It can take a few weeks to several months (~ 6 months). A person in 50 years of age cannot expect to recover the memory function to 20’s and 30’s overnight. The reason is because neurons have been deteriorating and dying since approximately twelve years of age; thus cannot easily estimate how many cells have been damaged and dying. Unfortunately, current technology does not allow us to both qualitatively and quantitatively estimate their condition at the cellular level. difference between 25mg 50mg and 100mg viagra