For listeners who are now paranoid about Alzheimer’s Disease after this week’s WBUR series, one heartening response came from a colleague’s father, Dr. Jack N. Alpert, a Houston neurologist with 43 years of experience. He pointed out that though Alzheimer’s disease is indeed common, so is misdiagnosis. Of the many patients he has treated who were initially thought to have Alzheimer’s, he said, perhaps 5 to 10 percent of them turned out to have something else — often something far more treatable, like depression.
When Alzheimer’s is suspected, he noted, patients need a full work-up for other possible causes of their symptoms, checking everything from their sodium levels to their thyroid function, as well as an MRI scan of the brain. Other tests may also cast light on the patient’s condition, including a look at the spinal fluid, but in his experience, neuropsychological testing remains the gold standard for the diagnosis at this point.
So if a patient seems to have Alzheimer’s, with all the confusion and memory loss we’ve heard about so vividly this week, what else might it be?
Dr. Alpert listed the other possibilities in order of how common they are in his experience, with the most common first:
There is something called “pseudo-dementia of depression.” Patients are brought to me sometimes when their thinking has slowed, their movement has slowed down, and if you ask them, ‘Are you depressed?’ they might say ‘No,’ but their behavior suggests depression, and we call that ‘psychomotor retardation’: Slow thinking, slow responses.
You can often distinguish that from dementia because there’s a sleep disorder, insomnia, and lack of motivation, preference to stay in the house, loss of appetite, a facial expression which is sad. Those are things that raise the question of depression. So depression causes a type of dementia which is reversible with medical treatment.
People who are heavy drinkers can show the same symptoms as Alzheimer’s, the same short-term memory loss. This is called “Korsakoff’s psychosis,” and it looks the same.
Many times, especially in the older population, people say, ‘I have one or two glasses of wine at night,’ which doesn’t sound too bad. But if you talk to a spouse, it’s more like a bottle of wine a night, and a cocktail. it’s always essential to get support on how much the patient really drinks.
Aphasia (language impairment)
Some people may appear incoherent and confused when in fact it’s a language disorder. And if that’s the case, there’s a localized lesion in the brain, in the dominant hemisphere, which is usually the left hemisphere. I have occasionally had patients who’d been thought to be developing dementia and in fact had aphasia.
A patient with aphasia could have what’s called paraphasia, and that means misusing words. For example, saying “pour” instead of “floor” — that’s called a “phonemic paraphasia.”
Or instead of “door,” they might say “window;” they use the wrong word, and that’s known as a “literal paraphasia.”
One that’s frequently confusing is what’s called a neologism, when someone makes up a word. So instead of saying “shoe,” he might say “flubscum.” That particularly would suggest to someone who is not aware of aphasia that maybe he’s a got a progressive dementia, when in fact it’s a language disorder.
Aphasia may come from a tumor, which might be operable; it might come from a couple of strokes in that area, or it could be an infection affecting that part of the brain.
Among metabolic abnormalities that might produce Alzheimer’s-like effects are hypothyroidism — low thyroid function — especially in older people. I’ve had patients who were severely hypothyroid, with slowed thinking and movement, and in fact it was reversible.
Another possibility is vitamin B12 deficiency, also known as pernicious anemia. In older people there may be gastric atrophy which prevents absorption of B-12. So you can have even a reasonably good diet and still have a B12 deficiency. and you may even be taking multivitamins and still have a B12 deficiency.
Other metabolic abnormalities such as low sodium, diabetes with high blood sugars, and liver or kidney failure should be excluded. Syphilis, HIV-AIDS and a frontal lobe brain tumor should also be ruled out.
But those are all rare sources of misdiagnosis. Most often, when a tentative Alzheimer’s diagnosis turns out to be wrong, it’s depression.