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Normal Forgetfulness vs. Pre-Dementia: How to Distinguish Them

Normal Forgetfulness vs. Pre-Dementia: How to Distinguish ThemA 70-year old man comes into your office and asks: “Doctor, I keep misplacing my keys-am I getting Alzheimer’s?” You detect the note of anxiety in his voice, and you want to give an answer, and soon.

Here is a reasonable approach, based on the latest research data.

First, rule out dementia.

If you haven’t reviewed them lately, the DSM-4 criteria for dementia are actually more stringent than you might recall.

Your patient must meet the following three criteria:

1. Significant memory impairment.
This is most easily tested by asking them to recall the date, and to perform a simple delayed recall task, such as repeating and then remembering three unrelated words after two minutes of delay. If family is present, ask them whether they’ve noticed a significant decline in the patient’s memory over the last few years; it’s probably as reliable as any office-based testing you can do, according to at least one study (Harwood et al., Age and Ageing 1997;26:31-35). Ask specifically if they have noticed the patient asking the same question or telling the same story repeatedly.

2. At least one of the following:
• Apraxia. Ask: “Have you had problems doing simple everyday tasks, like getting dressed, balancing a checkbook, driving, and preparing meals?” Asking whether there have been problems using the TV or DVD remotes is even more sensitive but may well lead to false positives!
• Agnosia. Ask: “Have you had problems recognizing people whom you really know?”
• Executive functioning impairment. Ask: “Have you had problems planning things and getting them done, like cooking a meal or a gardening project?” You can also have patients do the clock-drawing task: “Draw a clock on this page and draw in the hands to show ‘ten after eleven.’”
• Aphasia. Ask: “Have you been having real problems remembering the right word for things?” “Have you had trouble understanding what people are saying to you?”

3. The symptoms must significantly impair everyday functioning. The best way to ascertain this is by asking if the patient has been requiring someone else’s help in performing a basic activity of daily living. Ask: “Have your memory problems made it necessary for you to get help with anything, like shopping, balancing your checkbook, cooking, or driving?”

Second, rule out mild cognitive impairment.

Let’s assume that your quick dementia screen was negative. Most elderly patients with subjective memory complaints who do not have dementia generally fit into one of the following two diagnostic categories: Age Associated Memory Impairment (AAMI) or Mild Cognitive Impairment (MCI). (I am assuming, of course, that you have already considered other common causes of memory impairment, such as depression, anxiety, medication side effects, substance abuse, and medical illness.)

You and your patient both hope that the problem is AAMI, otherwise known as “benign senescent forgetfulness,” and defined as the normal memory decline of aging. The key citerion is memory decline that is quite mild, not even close to causing functional impairment. Formal memory tests would show a memory below normal for a 25 year old, rather than below normal for your patient’s age. Clinically, AAMI presents with minor memory lapses, such as briefly forgetting someone’s name, or misplacing the car keys more often than in the past. Patients with AAMI probably do not progress to dementia any faster than the baseline rate (see the following good recent review of memory impairment for a discussion of AAMI: Feldman HH et al, Am J Geriatr Psychiatry 2005;13:645-655).

Normal Forgetfulness vs. Pre-Dementia: How to Distinguish Them

Mild Cognitive Impairment (MCI), on the other hand, is not so benign. Patients with MCI progress to dementia at a rate of 10-15% per year, vs. a 1-2% per year rate among normal elderly. How do you diagnose it? While there are different subcategories of MCI, the most common subtype is amnestic MCI, for which the Mayo Clinic recommends the following diagnostic criteria: (1) a subjective memory complaint, (2) normal activities of daily living, (3) normal general cognitive function, (4) abnormal memory for age, and (5) not demented (see Petersen RC, Arch Neurol 1999;56:303-308). As you can see, the key criterion differentiating MCI from AAMI is #4: abnormal memory for age, usually defined as 1.5 standard deviations below average for age on elaborate research-based memory tests.

Practically speaking, a patient with MCI will describe memory problems that are “pretty” severe (a judgment call for you), but that don’t quite lead to the impaired functional status of a patient with dementia. In contrast, the patient with AAMI has a degree of absent-mindedness that is annoying but not even close to causing functional decline (see a recent article in Rosenberg PB et al., Am J Psychiatry 163(11):1884-1890 for more diagnostic tips).

Can MCI be treated?

Unfortunately, trials of various strategies to slow the progression of MCI to dementia have been disappointing. For example, the Alzheimer’s Disease Cooperative (ADCS) randomized MCI patients to Ariccept(10 mg QD), vitamin E (2000 Study IU/day) or placebo. Aricept slowed progression only during the first 12 months of the three year study–by the end of the study, all three groups had the same rate of progression to AD. Vitamin E showed no beneficial effect at any point in the study (Petersen RC et al., NEJM 2005; 352:2379- 2388). Other cholinesterase inhibitors have shown similarly lackluster results, and as mentioned elsewhere in this issue, galantamine led to a higher mortality rate than placebo in industry trials.

In the absence of good medication treatments, many geriatric psychiatrists will focus on lifestyle changes. Recent studies have suggested that physical exercise (Podewils LJ et al., Am J Epidemiol 2005;161:639-651) and mental stimulation (Ball K et al., JAMA 2002;288:2271-2281) can both enhance memory. And don’t forget to encourage your patients to pay frequent visits to their primary care physicians for management of hypertension and high cholesterol, both of which can lead to vascular dementia.

TCPR VERDICT: AAMI: benign memory lapses; MCI: pre-dementia

Normal Forgetfulness vs. Pre-Dementia: How to Distinguish Them

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This article was published in print 5/2007 in Volume:Issue 5:5.


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APA Reference
Psychiatry Report, T. (2013). Normal Forgetfulness vs. Pre-Dementia: How to Distinguish Them. Psych Central. Retrieved on December 10, 2018, from https://pro.psychcentral.com/normal-forgetfulness-vs-pre-dementia-how-to-distinguish-them/

 

Scientifically Reviewed
Last updated: 24 Aug 2013
Last reviewed: By John M. Grohol, Psy.D. on 24 Aug 2013
Published on PsychCentral.com. All rights reserved.