One in five Americans over age 70 has mild cognitive impairment while not having dementia and a high percent of them may progress to dementia.

Dr. Brenda Plassman, a psychiatrist at Duke University Medical Center and her team examined 856 participants from the National Health and Retirement Study over a period of nearly five years. The findings show that 22 percent of the elderly participants had cognitive impairment that did not meet the criteria for dementia.

The study also reveals that 12 percent of those with mild cognitive impairment progressed to dementia and 8 percent died annually.

The study, which was done from July 2001 through March 2005, estimated that 5.4 million people older than 70 had some form of mild memory loss. This may include problems with attention, language, judgment or communication. Dr. Plassman said the data were worrisome as “the number of people with cognitive impairment is likely to increase significantly as the baby boomers age.”

“It’s a huge number. This is the first time we have an estimate of the number of Americans who have this condition,” Dr. Plassman said, according to the Washington Post, noting that the findings show that mild cognitive problems are as common as diabetes in this age group.

“Five million people is a lot. This is confirmation that this is a very big problem,” Richard Suzman of the National Institute on Aging, which funded the research.

The numbers raise more concern as mild difficulties with memory, in some cases, can be the first symptoms of Alzheimer’s or some other form of dementia, such as vascular dementia, which is often triggered by a series of small strokes.

Dr. Plassman underlined the fact that these mild memory problems are not severe enough to stop elderly from doing their daily activities, but they may cause them to have mild difficulty in completing their daily activities.

The study also draws attention on the need for families to look out for signs that their relatives are starting to lose their sharpness.

“From a personal perspective, we need to be more aware that our parents, our grandparents, our aunts and uncles may experience mild changes that may make them more vulnerable to being taken advantage of by scams. They may need more support and assistance in making more complicated decisions,” Dr. Plassman said.

She added that her team is also working on other studies looking on “how cognitive impairment with and without dementia affects families and the US health care system – so we wil be able to see the true human and economic costs of these conditions.”

The study appeared in the March 18 issue of the Annals of Internal Medicine.