Study Examines Memory, Cognition of Aging Americans

Using detailed evaluations of a nationally representative sample of 856 people ages 71 and older, the federally sponsored study concluded that 22.2 percent have begun to see their mental faculties decline, which translates to 5.4 million people. "It's a huge number," said Brenda L. Plassman, a psychiatrist at Duke University Medical Center who led the study being published tomorrow in the Annals of Internal Medicine. "This is the first time we have an estimate of the number of Americans who have this condition," she said, noting that the findings show that mild cognitive problems are as common as diabetes in this age group.

Combined with a previous estimate that 3.4 million Americans have full dementia, such as Alzheimer's disease, the new findings mean that more than one-third of people age 71 and older have some diminished mental function, the researchers said. About 25 million people in this age group live in the United States.

"This is important because the number of people with cognitive impairment is likely to increase significantly as the baby boomers age," Plassman said, noting that the new research found that 12 percent of those with mild problems go on to develop dementia, and about 8 percent die each year.

The magnitude of the situation surprised some experts.

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

For the study, researchers conducted a series of interviews with close family members of the subjects, who are participating in a larger study of health issues affecting seniors. They also conducted a battery of psychological and neurological tests, measuring the subjects' ability to remember things, make decisions, know where they are in time and space, exercise judgment, and communicate.

"The key here is we both examined them and tested the person directly, but we also spoke to a close family member who knows the person well to see how they think the person has been doing," Plassman said.

Of the 856 subjects, 241 had cognitive impairment but did not meet the criteria for full dementia. When adjusted for demographic factors such as race, age and socioeconomic status, that means one out of every five people in that age group.

"These problems may be noticeable to the individuals themselves and maybe close family members. These problems are not severe enough to stop a person from doing their daily activities. However, the problems may cause them to have mild difficulty in completing their daily activities," Plassman said.

Nearly a quarter of those with declining mental function had a chronic medical condition, such as diabetes or heart disease, which appeared to be the underlying cause of their cognitive problems, she said.

The findings underscore the need for families to be on the lookout for signs that their loved ones are starting to lose their sharpness, she said.