Mild Cognitive Impairment: Improving Memory Understanding Age Related Memory Loss

Content provided by the Faculty of the Harvard Medical School

Mild cognitive impairment

The distinction between normal age-related cognitive decline and abnormal cognitive dysfunction has blurred as researchers have focused on a particular group of older people: those who have memory problems that are above and beyond those seen in normal aging, but who do not have dementia. These people have mild cognitive impairment — the loss of memory or some other single mental function that is more persistent and severe than is seen in normal aging. But these people function normally in every other area of mental activity. Memory-related mild cognitive impairment, called the amnestic type, is far and away the most common form.

Experts have yet to reach a consensus regarding the significance of mild cognitive impairment. Some believe that mild cognitive impairment is essentially very early Alzheimer's disease, whereas others see it as a separate condition. Most agree, however, that like other memory problems, this disorder becomes more common with age, although there are no reliable estimates of just how prevalent it is.

A key difference between normal memory loss and mild cognitive impairment is the kind of information you forget. With normal memory loss, you tend to forget things that aren't terribly important to you — the name of a casual acquaintance, for example, or an appointment to have your teeth cleaned. With mild cognitive impairment, you may forget important information, such as the names of close friends or the dates of family members' birthdays that you used to know.

When taking memory tests, people with the amnestic type of mild cognitive impairment have more trouble remembering the details of pictures they've seen or paragraphs they've read just a few minutes earlier. Their memory difficulty is comparable to that of someone with very mild Alzheimer's disease. But on tests that measure other mental functions, such as their ability to keep the details of routine activities straight, people with mild cognitive impairment perform as well as healthy people and much better than people with Alzheimer's.

Studies show that the risk of developing Alzheimer's is much higher for people with mild cognitive impairment than for people with normal age-related memory loss. According to an analysis of several studies, among people ages 65–69, 6% of those with mild cognitive impairment progressed to having Alzheimer's for each year of the study, compared with only 0.2% of people of this age in the general population. For people ages 85–89, 25% of those with mild cognitive impairment progressed to Alzheimer's each year compared with just 4% of people of this age in the general population.

But this isn't to say that everybody with mild cognitive impairment is destined to develop Alzheimer's disease. One study followed people with mild cognitive impairment for three years, and during that period 81% didn't develop Alzheimer's disease. Of that large majority, 29% experienced no further deterioration, and 15% actually improved.

Researchers continue to study the link between mild cognitive impairment and Alzheimer's disease. A crucial question is whether treating mild cognitive impairment with certain medications can prevent future progression to dementia. A study by the National Institute on Aging found that people with mild cognitive impairment who took donepezil (Aricept) progressed to dementia more slowly than similar people who took a placebo.

If you suspect that you have mild cognitive impairment, see your doctor (see "When to see a doctor").

Last updated:	January 23, 2007