It is a fact that elder people start to get a little forgetful and confused and many times even depressed. It is not necessarily normal for old people. There are lots of medical troubles that can make an elderly person seem senile, but bad nutrition can also play a big role—particularly for someone who falls into the risk categories. Studies show that many elderly people are low in B vitamins, particularly cobalamin. Part of the reason is that you just don't absorb as many B's from your food as you grow older. Because some of the B's aren't absorbed all that well in the first place, older people can simply start to be deficient.
Then the deficiency makes them a little depressed, so they eat less and get even fewer B's, which makes them more forgetful, confused, and depressed and they end up in a nursing home. The food there might not help—institutional food often has most of its vitamins processed or cooked away.
Researches show that a large number of elderly people have overall B vitamin shortages that affect their health and their mental abilities. For example, many elderly persons are low on thiamin, folic acid, choline, and cobalamin. The statistics here are troubling because about a third of the elderly are low on pyridoxine, and thiamin deficiency may affect nearly half of all elderly people sent to hospitals. B shortages in older people are enough to cause depression, confusion, and memory problems, regardless of the fact that the usual blood tests are at normal levels.