(Reuters)
Updated: 2008-03-18 09:04

NEW YORK - In 2002, more than 5 million older Americans had cognitive impairments that did not reach the threshold for dementia, according to research findings published in the Annals of Internal Medicine this week. These impairments include some loss of memory and thinking ability.

The findings also indicate that about 12 percent of individuals progress from cognitive impairment to dementia each year.

"Cognitive impairment both with and without dementia can be a problem in late life, but the number of individuals affected by these conditions in the U.S. is unknown," Dr. Brenda Plassman, from Duke University Medical Center in Durham, North Carolina, told Reuters Health.

In a study of 856 people age 71 years and older evaluated between 2001 and 2003, Plassman's team found that 22 percent had some cognitive impairment that did not reach the level of dementia.

Among 180 subjects with cognitive impairment without dementia who were re-assessed 16-to-18 months later, 39 had progressed to dementia.

Plassman's group estimates that in 2002, about 22.2 percent (5.4 million) of individuals in the US age 71 years or older had cognitive impairment without dementia and that the annual rate of progression to dementia was 12 percent, as mentioned.

Plassman said her team is involved in many different types of studies looking, for example, on "how cognitive impairment with and without dementia affects families and the US health care system -- so we will be able to see the true human and economic costs of these conditions."

"Hopefully this research will also lead toward developing interventions and treatments, so that cognitive impairment is not one of the leading concerns in late life when our children are in their 70's and 80's."