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Tuesday, April 08, 2014

Depression and Alzheimer’s

Washington DC

A reader left a comment on a recent post pointing out that depression is also a relatively common cause of cognitive impairment.  Because of childhood trauma, he’d also experienced anxiety and PTSD, and I suspect they belong on the list of potential causes, too.  People sometimes ask me if depression makes a person more susceptible to Alzheimer’s.

The question is important.  There is certainly an association between the two, but the cause runs the other way: Alzheimer’s (or any other cognitive impairment) can cause people to be depressed, but there is no evidence that depression causes Alzheimer’s or even makes it more likely. 

So depression must be on the list of the causes of mild cognitive impairment.  If medical evaluation has ruled out the most obvious of the others, then depression moves higher in the list of possibilities.  If a person is seriously depressed, one can see how the depression might affect her ability to think well.  

Usually depression is obvious, but not always.  There is (or, at least, was) a stigma around the disease and people don’t want to acknowledge their inner pain.  They need to cover it up and mask it with a smile.  Even family members may not know how much the person suffers. 

In some cases the people themselves don’t even know they’re depressed.  I’m an example.  I now know that I was depressed for the first half of my adult life, but at the time I didn’t recognize it for what it was.  I didn’t have the usual symptoms: sleeping too much, being dysfunctional at work, thinking of suicide, and so on.  But I was almost always dissatisfied with my life, feeling I should be doing better, hyper-aware of my mistakes despite having what might have appeared to be a perfect life as a successful small-town doctor.  I was mostly miserable.  I thought my misery was caused by the difficulties of medical practice or my unreasonable expectations of life.  The possibility of depression never entered my mind.  It was more than a decade later, after I’d begun adequate anti-depressant medication and was beginning to experience how a non-depressed life felt, that I recognized I had depression. 

So, when faced with a person who has dementia of no discernible cause, a doctor must keep the possibility of depression in mind, even if the patient vigorously denies being depressed.  Having her doctor repeatedly return to the question of depression, however, can be frustrating for a patient who is convinced that she is not unusually depressed.  It can raise doubts about her own perceptions of her emotional state, especially if she does have minor bouts of mild depression.  It may also seem as if the doctor is trying to dismiss the seriousness of her complaints by pushing them off onto emotional causes. It’s a frustrating experience for both patient and doctor that can endanger mutual trust.

Mild cognitive impairment of no obvious cause is difficult enough an experience.  The confusion around depression can make it worse.


  1. I tend to blame my mental fog on depression. I am still denying there may be any other mental impairment there. At this point no ones knows which is causing my increasing inability. Reading specific instances of your problems, like playing Yahtzee with your grandkids, is helping me evaluate. Thanks again for being so open with us.

  2. Anonymous4/10/2014

    I wonder if it is not so much a question of whether depression causes cognitive impairment (or more serious dementia), or the cognitive issues potentially cause the depression. Rather, it could be that the same damage within the brain could be causing both. One manifestation might occur before the other, but the underlying damage could be the culprit. Just a thought.
    Thanks for your very helpful and informative blog.

    1. It's an interesting thought: Some third factor causing both. I haven't heard of anything like that, but I don't know why not.

  3. I think I was not as clear about the relationship between depression and Alzheimer's disease as I wanted to be. ANY kind of dementia can cause a person to be depressed; knowing what's facing them, almost anyone might suffer depression. And depression, especially when severe, can certainly impair one's ability to think well. What I wanted to be clear about is that depression does not have anything to do with the development of the specific form of cognitive impairment that is caused by Alzheimer's disease.

