Delaying retirement may be the key to staying mentally sharp and halting dementia a new study says. Years ago, retirement meant that at a certain age, you left work with a pension and from societies point of view, you needed to make room for younger workers as they entered the work force. Most older folks were sedentary. Years later, with active communities in areas such as Florida, most retirees stayed more active and physically fit by playing golf, tennis and exercising, and many began to also live longer with a noticeable problem in many as they aged...dementia. Whether it was called Alzheimer's disease, or some other type of dementia, many families watched as their under stimulated parents were less sharp than they were in their youth mentally, and some deteriorated and became disorientated as the disease progressed. There is now evidence that shows people who work longer, stay sharper and that the stimulation they receive is important to their mental acuity. Is dementia a normal part of aging or is it due to a lack of mental stimulation, the food that keeps the brain going? Check out this article on NBC news By Marilynn MarchioneThe Associated Press New research boosts the "use it or lose it" theory about brainpower and staying mentally sharp. People who delay retirement have less risk of developing Alzheimer's disease or other types of dementia, a study of nearly half a million people in France found. It's by far the largest study to look at this, and researchers say the conclusion makes sense. Working tends to keep people physically active, socially connected and mentally challenged — all things known to help prevent mental decline. "For each additional year of work, the risk of getting dementia is reduced by 3.2 percent," said Carole Dufouil, a scientist at INSERM, the French government's health research agency. She led the study and gave results Monday at the Alzheimer's Association International Conference in Boston. About 35 million people worldwide have dementia, and Alzheimer's is the most common type. In the U.S., about 5 million have Alzheimer's — 1 in 9 people aged 65 and over. What causes the mind-robbing disease isn't known and there is no cure or any treatments that slow its progression. France has had some of the best Alzheimer's research in the world, partly because its former president, Nicolas Sarkozy, made it a priority. The country also has detailed health records on self-employed people who pay into a Medicare-like health system. Researchers used these records on more than 429,000 workers, most of whom were shopkeepers or craftsmen such as bakers and woodworkers. They were 74 on average and had been retired for an average of 12 years. read more