Recommendations for Diagnosing Alzheimer Disease
NOVEMBER 20, 2019
Alireza Atri, MD, PhD: Brad, I want to turn to you. Is there a conceptual framework that you use to approach the diagnostic process that you would recommend?
Bradford C. Dickerson, MD: Yes. I think we’ve talked already about a complex array of terms that often are used to describe people’s diagnoses. For some years, I have had patients come back to my office after going through the diagnosis and say, “Well, last time you told me I have 2 diagnoses. I have a progressive aphasia and I also have Alzheimer disease.” And so, I think we and others in the field have been working for some recent years to try to organize that in a way that’s a little more understandable to ourselves and to our patients, and families, and constituents.
Currently, I think we advocate for a 3-step framework that starts by describing the person’s overall cognitive functional status. What we mean by that is, does the person have mild cognitive impairment? Does the person have dementia? Maybe they don’t even have mild cognitive impairment. Maybe they have some subjective cognitive decline that they feel they’re experiencing. And when Dr Shaughnessy tests them, they perform normally on neuropsychology tests. So in the beginning, we don’t always need neuropsychology. What we really need to do is interview the person and, ideally, an informant, and find out what they are lacking in terms of independent functioning. What have they lost? What do they need help with?
Getting back to what Marc and Mary were just talking about, this ultimately has major implications for the care plan. Establishing whether the person has mild cognitive impairment or dementia is very important, and I think that threshold varies from person to person and can be quite an arbitrary decision that really takes some clinical experience. Ultimately, what I like to ask people is, if you, as the care partner, can leave the person and go on a trip for a weekend or a week, would they function independently at the things that they need to try to get done to get by in daily life? If the care partner says, “No, I would never do that,” you can pretty comfortably say that the person probably has crossed the threshold into dementia. I think that’s the starting point, No. 1.
No. 2 is, what’s the particular cognitive behavioral syndrome that the person is experiencing? And this gets back to what Lynn was talking about before, in terms of, is the main problem memory loss? Is the main problem executive function? Is the main problem language? Are there multiple problems? A lot of times we see, I think, this common presentation of a person who has memory loss. They’re just not holding on to information, and they also have executive dysfunction. They’re not able to reason. They’re not able to perform tasks to the level that they used to be able to in order to get the job done to reach goals in a valid way.
I think that the syndrome is really meant to capture the major symptoms and signs that the person has of their illness. And that communicates important information to our colleagues and to the patient and family about where their problems are. I think it also allows you to highlight, as Marc said before, what their strengths still may be. If this person has a primary memory loss syndrome but their executive function is still good, maybe they can make use of strategies to compensate for some of the problems that they’re having with memory. If they have executive dysfunction, they’re probably not going to be able to do that. Ultimately, that cognitive behavioral syndrome, that second level of specificity in our diagnostic formulation, communicates, in shorthand, to us and to others what the person’s problems are and maybe what they can still do.
And then the third level is, what’s the brain disease that is the cause of the problem? Sometimes it’s multiple diseases. Often, it’s compounded by other medical problems or things like medication effects that affect brain function but are not necessarily a disease in and of itself. The most common, I think, is Alzheimer disease mixed with cerebrovascular pathology in an older adult population—people over the age of 70, 75. In the younger people, I think it can sometimes be a more pure condition, whether it’s Alzheimer disease, or frontotemporal degeneration, or Lewy body disease. Those can often be primary diseases, especially in younger people.
That’s really the 3-step formulation that we advocate that we try to follow. It’s not always possible to be 100% confident in any 1 of those levels, and I think that’s where we have to talk about likely due to Alzheimer disease or likely due to cerebrovascular disease, and rate our level of certainty so we can think about whether we need some additional specialty involvement. If so, what does that involve, and how important is that in thinking about the management? We don’t necessarily have to have the sophisticated biomarkers that we talk a lot about in every individual with dementia likely due to Alzheimer disease. I think there are plenty of people we can all diagnose with fairly straightforward assessments and tests and not do the multimillion-dollar work-up on, that we often end up spending time talking about in the more specialized cases.
Transcript edited for clarity.