Is it Forgetfulness or Dementia? How to Distinguish Mild Congnitive Impairment from Dementia, and from the Normal Process of Aging
by Alan Kronhaus, M.D., Health and Welllness Editor

There are few things that strike fear more deeply into the hearts of older Americans than Alzheimer’s disease. When I say “older” I’m not just talking about people who are old enough to be seriously “at risk” for dementia; I’m also talking about the so-called “sandwich generation” of baby boomers who are shouldering the responsibility of caring both for younger children and aging parents.

It’s one thing to care for aging parents who are reasonably in tact physically and mentally. It’s another thing altogether to care for aging parents with dementia, especially when the dementia is complicated by mental or behavioral disturbances such as depression, delusions, agitation, or aggression.

But I get ahead of myself. The main focus of my article this month is not managing dementia, which is an issue we recently reported on and will revisit in future issues. We’re focusing this month on diagnosing dementia and distinguishing it from mild cognitive impairment and the changes that are part and parcel of normal aging. One reason this is so important is that 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. To achieve the maximum benefit these drugs can offer, treatment should be started as early as possible in the disease process.

As we get older, most of us become forgetful or absent-minded. We speak jokingly of “senior moments” but we worry that such lapses portend worse things to come. Some memory loss is a normal part of aging; dementia is not. The question is how do we distinguish one from the other?

The first step in distinguishing “dementia” from the normal decline in memory that comes with age is to realize that dementia involves brain impairment that goes well beyond simple lapses in memory. More specifically, the diagnosis of dementia requires impairment in at least two areas or “domains” of cognition. The term “cognition” or “cognitive” refers to any “intellectual process” or “brain function” that involves the acquisition of knowledge through perception or thinking, as distinguished from instinct or emotions.

The so-called cognitive “domains” or 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 are useful because they assess several distinct cognitive functions, not just memory, and yield a score that helps physicians make a positive diagnosis of dementia. When administered serially 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 lower 20s suggest dementia. It is important to keep in mind that age and education affect a person’s MMSE score and, therefore, the interpretation of a given result.

The MMSE is also not a particularly “sensitive” instrument, which means that some people – especially those who are very well educated – can have significant decline in their intellectual function without demonstrating impairment of the MMSE exam. That’s why it’s imperative when considering a diagnosis of dementia for a physician to take a very careful history from both 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” and putting an MMSE into context is to understand the extent to which a person’s cognitive impairment causes social or occupational disability. In fact, the answer to that question provides the second key to answering the question of whether memory loss is or is not true dementia. The first key is impairment in two or more cognitive domains, not just memory. The second key 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, orientation and judgment who functions reasonably well at home or at work 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 new to many of us! Although mild cognitive impairment (MCI) is considered a risk factor for dementia, it can also be a relatively stable condition which does not deteriorate to dementia.

These distinctions are very important. To make them accurately, you have to be able to measure or “quantitate” the extent of cognitive impairment. The MMSE is one good way of doing that; however, it is not the most sensitive measure of cognitive impairment, and it must be administered by a qualified professional. There is another test that is much easier to administer than the MMSE, and is actually better at separating normal people from those with early dementia. In other words, it is a very good screening test for mild cognitive impairment.
The test is called “animal fluency.” It consists of asking a person 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. It’s just that simple. A score less than 15 indicates a very high probability of dementia: people with a score under 15 are 20 times for likely to have dementia than normal people. 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 or MCI. The next step in making that determination would be the extremely detailed testing of memory and cognition that is typically done by a neuropsychologist. You may want to consider such testing if you screen “borderline” on animal fluency, MMSE or both, and you really need to know your cognitive status, perhaps because you would initiate medical treatment if you and your physician deem that appropriate at the earliest signs of impairment. The side effects of the medication used to treat Alzheimer’s are generally not problematic, but the cost of the medication is around $1,500 a year, making it a significant consideration for most of us.

So far we’ve been talking about dementia in general. 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 specific diagnosis of Alzheimer’s disease is made on the basis of the history: what symptoms the person is experiencing, how those symptoms first appeared, how they progressed, and how they’re affecting the person’s life. There are no neurological tests or imaging studies for the disease although PET scanning has shown promise in that regard.

The criteria for Alzheimer’s are cognitive loss in two or more domains, as discussed above, which must have 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 possibility of 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 diagnosis 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, necessary, or widely available. It is also extremely expensive. The last time I looked, it is not covered by insurance when used to diagnose Alzheimer’s.

The mainstay of medical therapy for dementia is a class of drugs called the cholinesterase inhibitors, the most popular of which are Aricept, Reminyl, and Exelon. They get their names from the fact that they inhibit an enzyme that breaks down certain neurotransmitters, or “messenger molecules,” in the brain which, in turn, presumably improves communication among brain cells.

The key point about those drugs is that they do not “cure” the disease – they only affect symptoms. They may not even improve symptoms, although sometimes they do. They do slow the rate of progression of the symptoms associated with the disease – mainly the cognitive symptoms as opposed to the behavioral.

While that may not seem like much at first blush, believe me it’s a very big deal! Slowing the rate of functional 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 in that it works in the brain in a completely different way. It is also supposed to affect the underlying disease process, not just the symptoms. Currently it’s approved by the FDA only for use in moderate to severe dementia, but many physicians who specialize in treating dementia believe there is good evidence for starting it sooner rather than later. There are also physicians who 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.

Dr. Kronhaus is a recognized expert in the medical field and the owner of Doctors Making Housecalls, 919.932.5700, www.doctorsmakinghousecalls.com

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