Why Cant' We All Agree on a Diagnosis?

David Roeltgen, MD Health Guide
  • I would like to revisit three topics that I covered previously: the issue of depressive “pseudo-dementia,” the diagnosis of mild cognitive impairment and the fact that health care professionals do not always agree on a diagnosis.


          Each week I take part in our memory disorders consensus meeting.  Usually there are 3 neurologists, 1 psychiatrist and 3 nurse practitioners, all of whom have special training in geriatrics (medical problems of the elderly), dementia or both.  We discuss a few patients whom we have seen during the week to come to a consensus regarding the diagnosis and treatment recommendations.  Recently, we had to deal with the following conflict.  A patient was referred to us by an internist for evaluation, because the internist diagnosed the patient with dementia and started the patient on an acetylcholinesterase inhibitor (treatment for Alzheimer’s disease).  However, the patient’s psychiatrist told the patient that he (the patient) was depressed and had pseudo-dementia and should increase his antidepressant medication rather than take the dementia medication.  For those of you who read (and remember) my blog on pseudo-dementia, you will remember that I indicated that there were a few things to consider when making this diagnosis.  First, it should be clear that the patient is depressed and second, there should be evidence that the depression is the cause of the cognitive impairments that are causing the patient to appear to have a dementia. The psychiatrist and the internist agreed that the patient was depressed.  It is the second consideration that was the problem. Did he have dementia?  Let’s review the Alzheimer’s criteria now: trouble with daily functioning due to a disorder of cognition (thinking and memory) that involves 2 or more areas of cognition).  Well, our patient was functioning at home without any difficulties, although he planned to move in with his brother because he feared that in the future he might have trouble living alone.  The patient complained excessively about his memory problems and complained about trouble coming up with words.  Based on the plans to move into his brother’s apartment and the two apparent areas of cognitive impairment (memory and language), the diagnosis of Alzheimer’s disease was made.

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          The patient came to us confused.  He asked first, “Do I have dementia?” and second, “Should I take the higher dose of antidepressant, the Alzheimer’s drug or both?”

    So what did we tell him?  First, we ordered neuropsychological testing.  I discussed this in a previous blog also.  To briefly review, it is detailed testing of the patient’s language, thinking, spatial, and memory abilities.  The results of this testing came back and we drew the following conclusions.  First, there was no evidence that the patient could not function on a day to day basis.  Given this conclusion, we could not make a diagnosis of dementia.  However, the neuropsychologist made a diagnosis of depression and mild cognitive impairment (MCI).  Remember, MCI is the diagnosis applied to someone who can function well, but who has one or more areas of cognitive impairment.  We all agreed that the patient did have depression and did not have dementia, but, some members of our group disagreed with the diagnosis of mild cognitive impairment.  Why?  Because the actual scores on most of the tests were, at worst, only mildly impaired and because of the fact that depression can cause impairment on neuropsychological testing.  Others in the group argued that the mild impairments were significant.  Why did these clinicians believe this?  Because, the pattern of impairments indicated that the patient was very smart and should have performed above average, not below average on the tests. Also, some error types were the kinds of errors made by people with dementia, not people with depression.  Lastly, it was noted that some of the tests that are typically impaired in people with depressive pseudo-dementia were performed well by this patient.  It was this pattern of results that led the neuropsychologist to conclude that the patient had mild cognitive impairment.


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          So what did our consensus committee agree to?  We agreed to disagree....So much for a consensus.  We all agreed that the patient had depression and should increase his antidepressant.  We all agreed that the patient could not be diagnosed with a dementia.  We did not agree about whether the patient had mild cognitive impairment or not.  We recommended that the patient be treated for depression and once the depression was doing better that he have repeat neuropsychological testing.  If the problem is pseudo-dementia (actually pseudo MCI), then he should do better on the repeat testing.  We also agreed to recommend that the patient stay on the anti-Alzheimer’s medication because if he stopped it before the repeat testing, the results would be confusing.


    Well, not only might those results be confusing, but the story about this very complicated patient may be confusing, especially if you have not had the opportunity to read the previous blogs that I referred to.  Let me summarize the major points.  First, depression may mimic dementia in the elderly.  Second, a diagnosis of dementia must include impairment in performance of daily functions.  Third, neuropsychological testing may provide important information.  Fourth, no matter how much information is available, it is still possible for knowledgeable clinicians to be uncertain or disagree about a diagnosis.  Medical care commonly requires decisions about patients be made when the situation is uncertain.  When that is the case, it is the job of the physician to first “do no harm” and to second present the best reasonable course of action to the patient.

Published On: October 08, 2008