In a previous post, I shared the good news that my cognitive decline has not been progressive, is not Alzheimer's, and (despite the occasional frustrations) is something I can live with.

It's wonderful news although I've been able only gradually to embrace it.

The good news may raise the question in the minds of some: If Alzheimer's is incurable, how could have you been cured?

The short answer to that is that I haven't been cured; I never had Alzheimer's in the first place.

The diagnosis I've been living with for over a year is wrong. And that may raise the question: If you had good doctors, how did they miss it? Why did they tell you that you had Alzheimer's when you didn't?

The short answer to this question is similar: They never did tell me that I definitely had Alzheimer's; they said it was almost certain, which I've always mentioned in my writing, but usually not emphasized, in articles, speeches, and this blog.

The longer answer to both those questions lies in the current diagnostic criteria for Alzheimer's, which are imprecise. I emphasize current because, as I'll explain later, those criteria are in flux.

Alzheimer's can only be definitively diagnosed by an autopsy that finds the telltale amyloid plaques and neuro-fibrillary tangles. Since it's not possible to make a certain diagnosis on a live patient, doctors assemble as much evidence as possible, then make the presumptive diagnosis from there.

The main problem is that the diagnostic criteria for Alzheimer's are subjective and uncertain. Here they are:

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  • The cognitive impairment has to be progressive. The trouble with this criterion is that early in the disease it can difficult to be sure that symptoms have gotten worse. In my case, the second set of cognitive tests—conducted a year after my first—did seem to show increasing impairment. But the progression was mild and maybe just random; maybe I had a bad day with the second set of tests.
  • Symptoms have to be bad enough to disable you in your daily life or work. This definition is a little vague. My neurologist did tell me at the time that I hadn't yet quite progressed this far, but it looked to him that I was heading there. On the one hand, I was working both as a writer of complicated material requiring specialized thinking and as a bookkeeper, and I became disabled enough to force me out of those jobs. On the other hand, I could still do other kinds of professional work: teaching college-educated people, participating in organizational leadership positions, and so on. Was I disabled because I couldn't do my usual work? It's not clear cut.
  • Memory must be more affected than other elements of cognition. I certainly met that criterion, but other kinds of dementia can have the same pattern.

Other causes of dementia have to be tested for and ruled out. But no tests exist for some causes of cognitive impairment (for instance, Lewy Body dementia) and other tests (such as an MRI for vascular dementia) are not always conclusive. So it's not really possible to rule out all other causes of dementia.

The point is that, especially early on in Alzheimer's disease, a doctor cannot make a definitive diagnosis. As a doctor, you do the best you can, but you're often wrong.

I fit three of these criteria and was close to the fourth. So, using these old criteria, a diagnosis of "mild cognitive impairment, almost certainly Alzheimer's" was justified.

So, the answer to the question about how I can now be cured of Alzheimer's is that I never had it in the first place. The early clinical diagnosis was wrong, as it sometimes is. And the answer to the question about my doctor's competence is that he did exactly what he was, at that time, supposed to do.

But medicine marches on; the symptoms previously diagnostic of Alzheimer's are no longer enough. By the old criteria I had it; by the new, not-yet-quite-in-place criteria, I don't.

Editor's note: David's journey with Mild Cognitive Impairment was chronicled in "Fade to Blank: Life Inside Alzheimer's," an in-depth look at the real lives of families impacted by the Alzheimer's epidemic. His story continues on his personal blog on