Pseudodementia / Dementia Syndrome of Depression Revisited

A little over a year ago I authored this blog post, which quietly became, far and away, the most popular blog post I’ve ever written. To date, it currently gets at least a half-dozen or more page views per day. In part, this is due to some propitious circumstances as far as Google search results go – if you do a search for “pseudodementia,” my article has the distinction of being the seventh hit for this search term (valuable real estate indeed!).

While convenient search result placement likely has much to do with the popularity of the article, I can’t help but somewhat buy into a theory I’ve heard my ex-wife voice on this subject. I don’t recall exactly what she said, but it was something to the effect of, “people want to have a reason not to fear for the worst.” In other words, there is certainly some attractiveness to the pseudodementia / dementia syndrome of depression (DSD) concept, and something that goes beyond just its parsimoniousness from a clinical science perspective. Caregivers, family members, and dementia sufferers all would like to believe that the memory problems they are seeing are not a harbinger of an irreversible dementia such as Alzheimers.

So let’s revisit the issue. Psychiatrist Walter Brown notes:

“…The long-term prognosis for this condition is not as benign as we originally thought or as the term suggests. Elderly patients with depression and cognitive impairment, even when the impairment improves somewhat as the depression lifts, are at a substantially greater risk for dementia than their nondepressed counterparts.14 Pseudodementia may be an early sign of “true” dementia…” – See more at: http://www.psychiatrictimes.com/dementia/pseudodementia-issues-diagnosis/page/0/2#sthash.RsrwpXY1.dpuf (may require an email to read the entire article).

Basically, there is apparently some considerable support for the position that so-called “pseudodementia” (which, regardless of how you look at it, is not “pseudo” at all – regardless of the cause, it’s a dementia) may not be so apparently benign, and may simply be heralding the onset of chronic, progressive dementia frequently of the Alzheimers type or secondary to cerebrovascular accident, etc. One of the things I should point out (and I didn’t do so in my original blog article) was that in my approximately decade of experience in geriatrics, I cannot recall a single instance where I or my colleagues had erroneously identified a dementia as being secondary to, say, Alzheimers Disease, and later found out that depression was in fact the cause! This appears to agree with a meta-analysis on this subject – amongst community-dwelling older adults averaging in their mid-70s (74.4), the number of older adults who are found to have reversible dementia (presumably due to depression) was 11% – with only 3% completely reversing. That means that according to this meta-analysis – out of 100 older adults with dementia, you can expect perhaps three of them to completely reverse if their depression is aggressively treated. This doesn’t sound like DSD is a particularly widespread phenomenon…

I do recall one case where I was an intern performing neuropsychological testing in my role at the Dementia Diagnostic Clinic at the University of Medicine and Dentistry of New Jersey. There was a patient who showed evidence of confusion / disorientation, some short-term memory difficulties, and problems with her alertness. I recall a couple of issues that made her stand out from the typical patients at our clinic: one, she was young… if I recall correctly, she was somewhere in her mid-50s. Two, she had a notable, almost twitchy kind of tremor in her extremities, which was not the classic “pill-rolling” or primarily resting tremor you associate with Parkinson’s disease, nor the constant action tremor associated with essential tremor. This woman also suffered from Bipolar Disease and as we found out, had been chronically overdosing on her lithium medication – her cognitive symptoms, confusion, and tremulousness were all symptoms of lithium toxicity… which apparently is actually not hard to do if one, for example, does not stay properly hydrated!

Aside from that, in every other case I’ve seen where dementia was suspected due to a patient’s significant cognitive impairment, aside from where it was found later to be a delirium (e.g., cognitive impairment due to illness or infection) which later resolves, it always ended up being just that – irreversible dementia. Still, I do from time to time recommend that my patients be treated with an antidepressant, or receive therapy when I suspect DSD. Just in case.

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