Rates of Mild Cognitive Impairment Higher Than Expected

July 29 -- MONDAY, July 28 (HealthDay News) -- The growth in the number of cases of mild cognitive impairment in the elderly population is outstripping earlier predictions, Mayo Clinic researchers report.

"The rate of new mild cognitive impairment cases, in this group, was considerably higher than anticipated," lead researcher Dr. Ronald C. Petersen said in a news release. "If we extrapolate Alzheimer's incidence rates to MCI, we would expect perhaps 1 to 2 percent per year, but our findings were substantially higher than that."

Petersen's findings showed new cases are now account for a rate of about 5 percent annually amongst the elderly.

He was scheduled to present the findings Monday at the International Alzheimer's Disease Conference, in Chicago.

For the study, Petersen's team collected data on 1,786 people aged 70 to 89 who participated in the Mayo Clinic Study of Aging. In 2004, all these people were cognitively normal.

The researchers found that after a year, 5.3 percent had developed mild cognitive impairment, which is the intermediate stage between normal aging and earliest Alzheimer's.

That rate of cognitive impairment increased with age, with about 3.5 percent of those aged 70 to 79 developing cognitive impairment and 7.2 percent of those aged 80 to 89 developing it.

Men were almost twice as likely to develop mild cognitive impairment compared with women, Petersen's team notes.

"These results underscore the urgency of developing new and better strategies to create disease-modifying therapies for Alzheimer's," Petersen said. "In addition, for public health purposes, we need to know how many people are cognitively impaired and potentially on the road to Alzheimer's."

Greg M. Cole, associate director of the Alzheimer's Disease Research Center at UCLA David Geffen School of Medicine, thinks these findings do not bode well for the future.

"The risk for Alzheimer's disease and dementia rises exponentially with age, so women have a higher risk of developing dementia and a higher prevalence of Alzheimer's in most studies simply because they tend to live longer," Cole said.