Dementia Syndrome of Depression, AKA “Pseudodementia”

Let’s talk about older adults and depression. According to the NIMH, the overall prevalence rate of depression in older adults overall (age 65+) is around one percent, which is considerably lower than estimates for their younger counterparts. That’s the good news. The bad news is that once you add the presence of physical ailments that might lead one to require hospitalization or home healthcare, prevalence rates rise to approximately 11 and 13 percent, respectively.

Depression is not a normal part of aging, and actually, is even more abnormal in older adults than in their younger adult counterparts! Also, memory loss is not a normal part of aging, either. There’s a connection between these two issues.

An interesting thing about major depression is that it expresses itself a bit differently in older adults than their younger counterparts. Before we get into that, let’s review the diagnostic criteria for clinical depression according to the DSM-IV (soon to be outmoded by the DSM-V, coming to academic bookstores near you).

As is the case with psychiatric disorders, you need to be diagnosed by having the requisite number of symptoms from all of the appropriate categories – a little from column A, a little from column B, etc. To be considered a major depressive episode, you need to be suffering from five or more of the following symptoms over a previous two-week period, AND two of the symptoms have to be either 1) depressed mood or 2) lack of pleasure:

1)    depressed mood (“most of the day, nearly every day”)

2)    lack of pleasure (AKA anhedonia)

3)    weight loss or weight gain

4)    insomnia or hypersomnia (sleeping too much or sleeping too little)

5)    psychomotor agitation or retardation (speeding up or slowing down)

6)    fatigue / lack of energy

7)    feelings of worthlessness or guilt, low self-esteem

8)    cognitive symptoms (memory problems, concentration problems)

9)    Suicidal thoughts

Note a couple of things about the above. We can kind of group the symptoms into two groups – there’s so-called “neurovegetative symptoms,” or basically symptoms that relate to basic systems of the body, chiefly relating to the autonomic nervous system. These include changes in weight, changes in sleep, energy levels, and cognitive symptoms. Then there are the more “existential” symptoms of depression remaining.

Older adults suffering from depression tend to express it more readily with neurovegetative symptoms, as opposed to the more dramatic, existential symptoms of depression like suicidal thoughts, depression, or guilt feelings, which may not even be present at all in older adults. Oddly enough, one can actually suffer from depression and not even know one is depressed – a not-unimagineable scenario where one suffers from so-called “depression without sadness,” – not an uncommon picture of depression in older adults.

Let’s talk about what’s commonly referred to as so-called pseudodementia (what I prefer to call dementia syndrome of depression – more on that later). The idea behind this is that a sufferer, typically an older adult, has a major depressive episode and due to how depression tends to manifest itself in older adults, they get diagnosed with dementia. An unsophisticated primary care physician seeing an older adult complaining of withdrawal from activities, poor sleep, weight loss, and increasing forgetfulness (all the while denying depressed mood) might miss what’s actually going on here.

The interesting thing about so-called pseudodementia is that it’s not actually “pseudo” at all – I suppose the thinking here is that since the cause of the memory problems in the case of pseudodementia is not “organic” in nature (although the NIMH confidently disagrees with this, stating “Depressive illnesses are disorders of the brain”), it’s really “depression masquerading as dementia.”

But of course this isn’t really accurate, depending on how you think about it –  the term “dementia” simply refers to the phenomenon of a sufferer who has significant deficits in cognitive functioning (e.g., such as memory plus one other important domain of functioning, such as language or attention), leading to significant deficits in social or occupational functioning. It’s a term that’s agnostic about causes – dementia can be caused by Alzheimer’s disease, strokes, medications, metabolic illnesses, and a whole host of other causes. It’s an umbrella term. Dementia can be stable, progressively declining, irreversible, and sometimes (as is the case with depression) – reversible. Therefore the term I believe is more accurate than pseudodementia, again, is dementia syndrome of depression, or DSD.

Of course, things become more complicated when you drill down into the phenomenon of late-life depression. Not only does it express itself differently, the presence of a depressive episode in an older adult also tends to be associated with an elevated risk of being later diagnosed with dementia. And, dementia tends to be associated with depression (particularly in the early stages). Still, this entire phenomenon is why it’s critical for any practitioner – if you’re working with an older adult and you suspect DSD, you need to aggressively treat this person for depression before you can definitively diagnose other causes of dementia (e.g., such as dementia secondary to Alzheimers Disease). In many cases, if the depression is successfully treated in a person suffering from dementia secondary to depression – the DSD lifts and the older adult is restored to baseline functioning.

15 thoughts on “Dementia Syndrome of Depression, AKA “Pseudodementia”

  1. Pingback: Dementia Syndrome of Depression, AKA “Pseudodementia” | Alzheimer's Speaks Blog

  2. This is really important information. I’m afraid far too many older adults are diagnosed with dementia (or Alzheimer’s Disease specifically) before being treated for depression. I’ve also seen some of my music therapy clients with dementia improve significantly when we caregiving professionals targeted the depression as well as the dementia symptoms.

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  5. Very interesting blog. You say, “the presence of a depressive episode in an older adult also tends to be associated with an elevated risk of being later diagnosed with dementia.” I’ve often wondered, is there any evidence that the antidepressants actually cause memory loss? Has there been any research in this area?

    • Neela, sorry it took so long to respond. No, I’m not aware of antidepressants being associated with memory loss, and I’m actually aware of a line of research that tends to support the idea of the use of some SSRIs (I’m remembering fluoxetine in particular – AKA Prozac) as being associated with rebounds in key markers for cognitive functioning, such as hippocampal volume.

      That being said, I know that antidepressants are no panacea and I think that the troublesome side effects of these drugs have been significantly understated.

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