Maintaining physical fitness through middle age could go a long way in keeping dementia at bay, a new study suggests. The study found that middle-aged adults who were in shape were significantly less likely to develop dementia or Alzheimer\'s disease by the time they reached 65 compared to their unfit counterparts, CBS News reported. The new research adds evidence for an effective way to avoid a disease that currently cannot be prevented, slowed or cured. About 5.3 million Americans are affected by Alzheimer\'s disease, according to federal estimates, and by the 2050, that number is expected to at least double. Alzheimer\'s is the sixth-leading U. S. cause of death, killing almost 84,000 Americans each year. \"Alzheimer disease and other types of dementia (all-cause dementia) are important public health problems, particularly in light of the aging population,\" the researchers, led by Dr. Laura DeFina, medical director of research at The Cooper Institute in Dallas write. \"Because of the effect of dementia on quality of life and functional status, identifying preventable causes of dementia is critical,\" they added. Researchers looked at more than 19,000 middle-aged individuals who were given a treadmill exercise test as part of a preventive visit to a doctor\'s office that occurred at a Texas clinic between 1971 and 2009. They eventually compared these results to available Medicare data on the individuals\' health claims to determine whether or not they developed dementia. Based on the amount of time those individuals could run on a treadmill, participants were divided into groups \"most\" and \"least\" fit. The researchers discovered more than 1,600 cases of dementia among the group, and a closer look revealed those who were most fit at an earlier age were about 40 percent less likely to develop dementia compared to those with the lowest fitness levels. The study is published in the journal Annals of Internal Medicine. From : ANI