As my patients aged along with me, I noticed both the expected increased numbers of people with some form of dementia and even more patients who were worried about this topic. Unless you have been away on a ten-year safari, you are very aware that dementia is a growing problem. Some 5.8 million Americans are living with Alzheimer’s disease, and similar numbers occur in most western countries. The incidence goes up with age, and we are living longer. As I responded to a questioner recently, the only way I know of to avoid getting the disease is to die young (which I don’t recommend as a preventive strategy).

The subject gets complicated because normal aging is often accompanied by some mild memory loss. A not-unfamiliar dialog between a couple in their 70’s might be like this:

“I was thinking we might watch a movie – the one with that actress we both like.”

” The one that starts with M?”

“Yes, Meryl.”

“Which movie?”

“Oh, the one we thought was out of her usual.”

“You mean that comedy?”

“Yes, about a wedding.”

“OK – the Abba musical.”

“That’s the one!”

Mild changes in memory or less ability to quickly learn new facts are both common as we age and do not usually interfere with functioning.

There is also a condition called mild cognitive impairment (MCI) in which the changes in thinking and memory are more than one would expect with normal aging but not severe enough to be called dementia. The latter usually includes both memory loss and some other symptoms such as trouble with word-finding, getting lost in familiar places, inability to cope with unexpected events or handling complex tasks. Some, but by no means all, people with MCI will go on to dementia and doctors really cannot predict which will.

If a person appears to have dementia, the task of the primary care physician, often with the help of a neurologist, is to decide what is causing the dementia. While Alzheimer’s disease is the most common, there are a variety of other brain diseases that can cause dementia. While there are some clues to be gotten from detailed brain imaging, particularly the PET scan, Alzheimer’s is, in essence, a clinical diagnosis, as there are no blood tests that can be used. It is important to not overlook the treatable causes of dementia. Depression can cause a “pseudo-dementia,” and a variety of medications can do this, including many that are used by the elderly. Both B12 deficiency and an underactive thyroid can cause dementia; while infrequent, testing for these is easy and reliable and should always be done once.

To complicate matters, a group of neurologists specializing in dementia have recently proposed that, particularly in the oldest group, over 80, a newly described condition they call LATE, for “limbic-predominant age-related TDP-43 encephalopathy,” may be even more common than Alzheimer’s and may co-exist with it. Their main reason for bringing this to doctors’ attention is that this condition does not respond to the medications used now to slow the progression of Alzheimer’s. The main reason, in general, to try to make a specific diagnosis is to guide treatment. There are no cures for Alzheimer’s or most of the other dementing illnesses. The medications we have are modestly useful in slowing the inevitable progression of the disease, but that is all they do.

Can you ward off Alzheimer’s without dying young? About all we know is that regular exercise does lower the incidence of dementia, and that a healthy plant-based diet also has modest protective effect. Keeping the brain busy by learning new things is also probably helpful.

So, if your only problem is occasionally forgetting where you left the keys but do find them, you can relax. You probably do not have Alzheimer’s. Get out there and exercise, eat healthily, and learn a new language.

Edward Hoffer is an internal medicine physician and author of Prescription for Bankruptcy: A doctor’s perspective on America’s failing health care system and how we can fix it. He blogs at What’s wrong with health care in America?

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