How to distinguish mild cognitive impairment from dementia from the normal process of aging

by Alan Kronhaus, M.D., Co-Founder & CEO, Doctors Making Housecalls

Few things strike fear into the hearts of older Americans than Alzheimer’s disease. Not just those old enough to be seriously “at risk” for dementia; but also the “sandwich generation” who are caring for both their children and aging parents. Aging parents with dementia that is complicated by depression, delusions, agitation or aggression is a whole different story.

As we get older, most of us become forgetful or absentminded. Some memory loss is a normal part of aging; dementia is not. The question is how do we distinguish one from the other?

Dementia involves brain impairment far beyond simple lapses in memory. The diagnosis of dementia requires impairment in at least two areas of cognition. Cognitive functions include memory, abstract thinking, calculations, concentration, decision-making capacity, visual-spatial perception, and judgment. In other words, “memory” is but one cognitive function. Tests for dementia assess several distinct cognitive functions, not just memory, and yield a score that helps physicians make a positive diagnosis of dementia. When administered over time, they also help to quantify changes in cognitive function, which helps physicians gauge a patient’s response to treatment.

The most widely used test for cognitive function is the Mini-Mental Status Exam or MMSE. A perfect score on the MMSE is 30 points. A score in the low 20s suggests dementia, but age and education affect a person’s MMSE score and, therefore, the interpretation of a given result.

The MMSE is not a “sensitive” instrument, which means that some people – especially those who are very well educated – can have significant decline in their intellectual function and score well on the MMSE exam. That’s why it’s imperative for a physician to take a very careful history from the patient and the patient’s family, and to put the MMSE test score into context of the whole person.

Part of assessing the “whole person” is understanding the extent to which a person’s cognitive impairment causes disability. There are two keys to use when deciding if it is true dementia. The first is impairment in two or more cognitive domains, not just memory. The second is functional decline significant enough to cause social or occupational disability.

Since the diagnosis of dementia is based on those key findings, a person with significant memory loss but without other cognitive impairments does not meet the criteria for dementia. Similarly, a person with minor impairment in memory and judgment who functions reasonably well, does not “qualify” for a diagnosis of dementia if the impairment is not disabling.

Mere subjective memory loss is not considered a risk factor for dementia, which probably comes as good news to many of us! Although mild cognitive impairment (MCI) is considered a risk factor for dementia, it can also be relatively stable condition which does not deteriorate to dementia.

To make these distinctions accurately, you have to be able to measure the extent of cognitive impairment. The MMSE is one good way of doing that, but it must be administered by a qualified professional. There is another test that is much easier to administer than the MMSE, and is better at finding those with early dementia

The simple test is call “animal fluency.” A person is asked to name as many different animals as they can within 60 seconds. Responses are recorded verbatim. The score is the number of novel animal names generated. A score less than 15 indicates a very high probability of dementia. Scores between 12 and 15 might be considered mild cognitive impairment (MCI).

Other than the test for animal fluency and the MMSE, there is no easy way to distinguish early dementia from normal aging. The next step would be the extremely detailed testing of memory and cognition by a neuropsychologist. You may consider such testing if you screen “borderline” on animal fluency, MMSE or both, and you need to know your cognitive status to initiate medical treatment if you and your physician deem that appropriate. This is important because there are drugs available to treat dementia – drugs that can slow the rate of decline in cognitive function as well as the progression of other symptoms. Treatment should be started as early as possible in the disease process for maximum benefit. Side effects of the medication used to treat Alzheimer’s are generally not problematic, but medication can be expensive, making it a significant consideration.

There are many forms of dementia, the most common being Alzheimer’s disease. Dementia can also be caused by vascular problems, drugs or infection. The diagnosis of Alzheimer’s is made on the basis of the history: symptoms the person is experiencing, how they first appeared, how they progressed, and how they’re affecting the person.

The criteria for Alzheimer’s are cognitive loss in two or more domains, with insidious onset and gradual progression. The abrupt onset of cognitive impairment suggests vascular dementia, and prominent fluctuations in cognitive abilities points to a form of dementia called Lewy body, which is rare, or the dementia caused by medications, which is fairly common. Dementia accompanied by a progressive difficulty walking might be caused by hydrocephalus, or fluid on the brain, which is important to diagnose because it can be treated and cured. Hallucinations or delusions occur in the later stages of any type of dementia, but may be a prominent feature of Lewy body dementia or dementia caused by drugs.

In patients whose condition is atypical for Alzheimer’s, it is important to rule out other causes of dementia by examination, laboratory tests, and in rare instances neuroimaging. Although Pet scanning can now establish the diagnosis of Alzheimer’s disease, it is not recommended. It is also expensive, and is not covered by insurance when used to diagnose Alzheimer’s.

The main medical therapy for dementia is a class of drugs called the cholinesterase inhibitors, (Aricept, Reminyl, and Exelon). They inhibit an enzyme that breaks down certain “messenger molecules,” in the brain which, in turn, improves communication among brain cells.

These drugs do not “cure” the disease, they only affect symptoms. They may not even improve symptoms, but slow the rate of progression of the cognitive symptoms associated with the disease.

Slowing the rate of decline in patients with dementia can make a critical difference for them and their caregivers. It may well extend the time a patient can live independently, and postpone the need for supportive services or transfer to a long-term care facility.

There’s a relatively new drug on the market for treating dementia called Namenda. It’s different from the cholinesterase inhibitors. It works in the brain in a completely different way. It also affects the underlying disease process, not just the symptoms. Currently it’s approved by the FDA for use in moderate to severe dementia, but many physicians believe there is good evidence for starting it sooner rather than later. Some physicians believe that “if a patient deserves one drug, they deserve both,” meaning that they start treating dementia patients with a combination of a cholinesterase inhibitors and Namenda – two drugs instead of one.

If you are concerned about memory loss in yourself or someone close to you, see your primary care physician. He or she should be able to evaluate your cognitive status, or refer you to someone who is knowledgeable in this specialized area.