There are all sorts of conditions that can cause dementia or memory loss. Depression can cause symptoms that are similar.

Something as simple as a serious B-vitamin deficiency can also cause such symptoms. It can be a lack in the diet or an inability to absorb what they consume.

In one case a man developed a pocket in his stomach that interacted with his high carbohydrate diet so it acted as a personal brewery. He was constantly borderline drunk even though he was a tea-totaler. A simple operation eliminated the pocket and restored mental function.

One recent study I read recently showed that something as simple as getting a correct prescription glasses caused a large number of nursing home inmates to become markedly less depressed and much more alert.

Suspected dementia or memory loss needs to be evaluated professionally. Even then I suspect that far too many people settle for the first opinion that it is 'just a part of getting old'. So don't be shy about getting a second or third opinion.