Sunday, December 04, 2011

The Reversible Causes of Dementia

I'm writing this post because the New York Times has been writing about how thyroid disorders and Vitamin B12 deficiency can be responsible for neuropsychiatric symptoms. 
Read the article about Vitamin B12 here.
Read the article about Thyroid function here.  

This is news?  When I was in medical school, the knee jerk response to memory complaints was to order labs to rule out the reversible causes of dementia: CBC, Chemistry panel, VDRL (syphilis), thyroid function tests, folate and B12 levels, urinalysis, and then perhaps a brain CT.

So let me tell you how a physician thinks about dementia.  First let me tell you what dementia is: the decline in cognitive function from a prior baseline, often seen by the patient as memory problems, beyond what would be expected with normal aging. 


A patient presents with complaints of memory problems.  The physician (usually an internist or primary care doc) takes a history: when did this start, did anything precede it, are things stable or getting worse?  What exactly is happening and is the patient actually having memory problems?  Sometimes people think they are having memory problems, but really what is happening is that they are anxious or distracted, so the information never makes it into their brain to be retrieved or remembered later.  "I told my husband to take out the trash during the Super Bowl and he didn't remember to do it."  A quick measurement of memory may be done, such as the Mini-Mental Status Exam, which tests a variety of components of cognition such as orientation, the ability to immediately recall, memory, concentration, the ability to follow directions, and the ability to copy a diagram, write a sentence, and follow a written command.  It's a simple test, and most people get perfect scores, and it's a quick way to follow progress over time.   A physical exam is done, including a neuro exam, and if there are focal findings --like the absence of reflexes or weakness, or loss of sensation, or a history of loss of consciousness, seizures, or a head injury-- these are noted. 


The only way to be 100% certain of the type of dementia is to biopsy the brain.  We don't generally do that.  Instead, we rule out the "reversible" causes of cognitive decline-- infections, thyroid disorders, neurosyphilis, folate orVitamin B12 deficiency, or metabolic problems such as confusion with markedly elevated blood glucose or neuropsychiatric symptoms with hyperparathyroidism.  Some of these illnesses are discovered with blood tests, others require a scan to look for anatomical lesions, like hydrocephalus, stroke, subdural hematoma.  If a reversible cause of dementia is found, it can be treated and it will often get better. Oh, and I should add that Major Depression can mimic mild dementia, and this too can be treated, it's called pseudo-dementia and when the depression gets better, the dementia gets better.


If a patient has dementia, and the reversible causes are ruled out, then the diagnosis of depression is based on the features of the disorder and the course it takes.  Alzheimers' disease is the most common type of dementia, and it has a progressive course with some predictability.  Patients with Alzheimer's disease will have a good recall for past events, but they may forget more recent events.  Personality and social appropriateness are preserved until well into the illness, and the early stages are often rather subtle.  Decline can take place over a few years or many years, but the course is always progressive. Medicines, such as Namenda or Aricept may be prescribed in the hopes of slowing the course, and patients with vascular dementia may be told to take aspirin to prevent future episodes.  While patients have good days and bad days, these illnesses do not remit.

Vascular dementias progress in a more step-wise course.  Patients will have a sudden onset of impairment, but things stay at that level for a while, until another event happens and there is another sudden decline. The course is less predictable with regard to what faculties are compromised when.  Some patients have both forms of dementia, or a mixed etiology. 

Other forms of dementia include Pick's disease (fronto-temporal dementia), Lewy Body dementia, and dementias associated with Huntington's Disease, Parkinson's Disease, and HIV, and dementia due to repeated brain trauma.

Okay, this is my quicky discussion of  dementia.  Please don't use this as a comprehensive resource, it's mostly off the top of my head.  Roy can pipe in with all the things I missed, I'm sure there are plenty.




12 comments:

ashwaria said...

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Dinah said...

Which reminds me, I forgot to mention medication/drug induced causes of cognitive impairment, including benzodiazepines, as a cause of reversible decline.

This is the first useful piece of spam we've gotten.

Carrie said...

You could interview my psychiatrist for this one, as treating dementia is what he does for a living. I'm just a holdover from residency as usually 30 year olds don't get dementia. :) So... the interesting part about that is CADASIL - one way dementia can strike the young. And in those with brain changes due to migraine (white matter lesions) plus other vascular disorders (essential hypertension in a young, fit person; avascular necrosis; other types of bleeding, clotting or vascular issues), it's not outside the realm of possibility that CADASIL could be an endpoint. It's a cross between a stroke disorder (more characterized by TIAs) and a leukodystrophy (bad...). You can test for the gene, but the question is, would you want to know?

Anyway - I think the normal pressure hydrocephalus cause of dementia symptoms is another one not to forget about. This one can take a quick witted 65 year old and turn them into someone looking rather depressed and/or suffering from dementia in a pretty rapid fashion, and a VP shunt or other type of shunt can restore them to prior functioning in many cases.

That was the case for a family friend. And this brought up a lot of conversation about Alzheimers, or as my grandmother relentlessly said over the years "Old Timers" (I think it's programmed into older people to call it this). I can remember many conversations where she would say things like, "There is no Old Timers in our family. We just don't have these things." It's amusing now that I think back on it, that she is the one to have severe dementia. :-/ She's 89 but hers was sudden onset - nothing slow or gradual and nothing caused by strokes. I've tried to find information and to figure it out, but dementia patients read the textbooks about as well as premature neonates. SO...I've got nothing. One day she was fine, then a month or so later I heard she was a mess and leaving the apartment at night with no oxygen on and half-dressed. (Note: lack of oxygen = another cause of memory and confusion issues.) Then - on the day of my bridal shower, which she was unable to attend, we got a call that she had unwittingly barricaded herself in the activities lounge and was chucking seashells off the table at the staff. (You go, Nana!) She has since definitely become better than at that time. No thanks to Namenda or Aricept, both of which really messed her up. (Namenda, incidentally, worked wonders for my migraines for awhile... *grin* )

So I guess the only thing I have left to do in this comment is to quote Forrest Gump - Life really IS like that box of chocolates - you definitely never know what you're gonna get. I'm glad for the good days. I'm so glad she was able to come to my wedding ceremony. I'm glad the other night, when we took my new car over to see her, she was able to look out the window at 9pm, wave and smile, and then talk to me when I went in. I don't understand it, but I'm glad for it.

Dementia is a kidnapper of a human being, where you are left with the shell of a person but without their essence. It's heartbreaking.

wv sionfule = Not sure, but sounds like it should be some category of a work of music. :)

Anon5 said...

where's the line between severe cognitive impairment - caused by, say, a severe neurochemical depression, and dementia? Not a flippant question, a real one. I'm talking about severe cognitive impairment including almost complete inability to focus or remember or attend to conversation, forget about ability to read, watch a movie, etc.

Dinah said...

Carrie, Thank you that was great.

Anon5, I'm not sure what the question is. There's not a "line" that I can think of. Dementia is a permanent decline. If it's caused by severe depression, it remits when the depression remits (with or without treatment) and it never was a true dementia, but we call this a "pseudo-dementia" because it mimics dementia. It can be difficult to tell one from the other, but if someone has classic symptoms of depression (sadness, loss of interest and energy, sleep and appetite changes, suicidal thoughts, inappropriate guilt, etc) then the patient would be treated for depression with the hope that the cognitive state would improve.

CatLover said...

I have zero faith in doctors to figure this stuff out. My grandmother was psychotic from drug side effects due to new drugs she got in the hospital, and they were going to stick her in the mental hospital. My mom had to yell at the doctors to get them to listen - that is was a drug side effect. That my grandma did not normally behave in that way. The doctors refused to listen until my mom got harsh with them. The meds were changed, and my grandma was just fine again. Doctors often just ASSUME what the problem is. Do you think that doctors routinely run these blood panels (which would not have detected my grandma's problem, I realize)? I really doubt it.

Carrie said...

CatLover,

I actually understand that quite well. I've had anticholinergic toxicity a few times from medication interactions, and thank GOD I used to work in the one ER I went to in the middle of it, and my best friend came back in from home because he felt like something was off when I had spoken to him. If it hadn't been for him, I'm pretty sure I wouldn't have seen the light of day for awhile. They would have definitely thought I was on some sort of drug high or just crazy. The thought of that, once the effects wore off and I did return from the land of delirium, was pretty upsetting.

And my grandmother - one of the times she was inpatient (I think the time before the seashell chucking contest), an internal med doc prescribed haldol 4 times a day plus something else. My mom would call me with updates of what was going on, and then I'd flip out, and she'd say, "Hmmm maybe we didn't hear the doctors right." NO you heard them right - they're just being ridiculous - call them back with the following: "No FRIGGING way. Are YOU insane?! Fix this. Yesterday."

It's scary what happens to people with advocates, let alone without...

wv = caloid... a colloidal calorie, perhaps?

Liz said...

great information, especially for those of us, uh, shall we say, mature adults who worry about the memory thing.

http://pocketshrink.blogspot.com

Anonymous said...

So what about neurofibromatosis that's invaded the cervical spine and brain? Couldn't that just look like memory fog if the patient was high-functioning and had good days and bad days?

I'm aware of someone who told her doctors she had "bumps" along her inner arms but none of the physicians bothered to do a full workup because she was also transiently psychotic at the time. Everyone attributed her fogginess to psychiatric problems.

PDFdoc said...

I think that the bottom line that we should take from many of the comments, is that it seems that physicians were forgetting the basics of diagnosis: history and physical. I remember learning these principles in second year medical school, and we undertook weekly sessions in hospital (our first experience). In the first, we were taught how to take a proper history, and were sent off to see a real patient, take a history, and write it up. In fact, later, we were even taught ways to cut off a patient to try to shorten this process. After that, our weekly sessions were on physical examination.

The emphasis was on physical examination (including the psych exam). Yet, we know that at least 80% of a diagnosis is based on information gleaned during the history. But, taking a good history, and not cutting off the patient or family, is time consuming. I fear that physicians sometimes minimize the history, and rely on physical exam findings, in the interests of saving time. This can lead to errors...

I book more time for patients than many of my colleagues, just to have a chance to listen to the patient, and hopefully benefit from this information. This is why psychiatrists book way more time for their patients than internists or surgeons...I think that many of the physicians related in the comments were internists, and rushed internists falling into the trap of minimizing the importance of a good history. Please remember that there are many good physicians out there that don't fall into that trap!

Carrie said...

In my earlier days of lots more hospital admissions, my doc would send the 1st year med students in to do the interview - in hindsight I probably tortured them - I'd give them books to read on relevant topics - I'm sure by the time they were done they never had such a long winded patient again. It's boring and lonely spending so much time in hospitals (so boring and lonely, I'm not sure I knew what to do with myself other than go into nursing since thats all I spent time around for quite awhile.). I spend so much time chatting with families now - I don't like to think I wouldn't have been that way without my experiences, but I'm sure they didn't hurt. I don't say a word about my experiences to patients except on extremely rare occasions, but you can tell when someone else gets it. Everyone has different reasons for being there and different stories, but going thru the health care system royally sucks. It's nice to have professionals who make it suck less. :)

Pam said...

A really important thing you left off your list is Lyme disease, and other associated tick-borne microorganisms. These can and often do cause neurosychiatric issues, and severe "brain fog" is a very typical symptom.

This is especially true in a state like Maryland, a real hotspot for Lyme