Studies gain insight into elder's mild cognitive impairment (4/11/2008)

A recent study, finished by Prof. HAN Buxin and colleages in the CAS Institute of Psychology, showed that the executive functioning of working memory in people suffering from mild cognitive impairment (MCI) is similar with that of the normal elderly, throwing weight on the hypothesis that MCI is an accelerated form of normal aging.

MCI is a transition stage regarding the cognitive states from normal aging to Alzheimer disease. Although the MCI patients have a poorer memory (dysmnesia) than their healthy counterparts, their cognitive capability still functions flawlessly and they are able to take care of themselves, maintaining a normal living pattern both in quality and rhythm.

Studies indicate that the MCI incidence rises with the increasing of age. For the people in their sixties, seventies, eighties and nineties, the rate is 2.4%, 4.8%, 10.4% and 22% respectively. Within one year, the transition rate from MCI to the Alzheimer's disease (AD) is 10%-15% while that of normally aging groups is only 1%-2%.

The three-year and five-year transition rates are 21.9% and more than 50%, respectively. Its ten-year survival rates for those with normal cognitive function, mildly-impaired cognitive function and moderately-impaired cognitive function are 89%, 80% and 71%, respectively.

The cross-section and longitudinal MCI studies over the past years suggest that episodic memory and executive function are sensitive to the normal aging process, and could be used as an effective index for depicting the transition from MCI to AD. However, the two major components of the executive function (the planning and inhibitive functions of dominant responses) are found to have different insensitiveness to the advancement of the aging course.

As reported in Nov. 2007 issue of the Aging, Neuropsychology, and Cognition, Prof. Han and co-workers compared executive functioning in 32 MCI individuals with that of normally aging controls. They discovered that MCI has effects on planning but not on the inhibition.

Note: This story has been adapted from a news release issued by the Chinese Academy of Sciences

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