Everyone has experienced an Alzheimer's-like state at some point. Alzheimer's strongly resembles the effects of the sort of "brain fog" people get when they're overtired (or experiencing caffeine withdrawal), just without the simple remedy of rest.

The onset of Alzheimer's itself is recognizable more by 1. your begining to experience such "brain fog" states more and more often (when otherwise well-rested), and 2. your beginning to experience a bit of "brain fog" all the time, such that you at your "best" is no longer as awake/alert/aware as it was previously.

There's a bit more to it than that. I had a relative die of cancer recently, and it was a relief in a way because if they cancer hadn't got them, Alzheimer's would - and it would have taken much longer and been even worse for everyone.

The loss of memory in Alzheimer's simply means you stop remembering stuff. There's no brain fog so far as I can tell. You just - stop remembering.

It has a lot of unexpected practical effects. You can't give someone new stuff, because they won't recognise it as their's, or remember you gave it to them, and they'll think they've lost the old stuff (or someone has stolen it - which is a common delusion.)

You have to be careful about medication and feeding because they won't remember either. It becomes incredibly easy to overdose on meds by accident, or to forget to eat, or to eat too much.

Likewise shopping. When someone's memory is so poor they can't walk around a store and check things off a list, they need professional help.

After a while conversations become incredibly repetitive. In middle stage AS sufferers literally forget what you said at the start of a sentence before you've finished it. They forget they've already asked the same question six times in the last ten minutes - literally.

You can't teach them anything new at all. So if you try to buy various memory aids or anything that needs a bit of thought or learning, they won't find them useful.

Worst of all is the prospect of personality change. Some people become very agitated, abusive, and even violent - which can be a devastating surprise if they showed no signs of that before.

Eventually they stop recognising people or showing much awareness of their surroundings.

My relative actually became more settled and friendlier, which was a very good thing. But there were a couple of support meetings where we are all wondering which way things were going to go.

If they'd gone the other way, it would have been horrible - well, even more horrible - for everyone.

Oh geez. Don't worry about it. Classic "webmd hypochondria."

Shouldn't really assume that. I mean, yes, it's unlikely, but given that most of the research is around prevention of damage, surely it's better to get tested early if you even remotely suspect there is a chance of it being Alzheimer's.

Yes, actually one should assume that; not doing so is irrational. There are many other diseases that one might have without even knowing they exist. It would be extremely foolhardy to get tested for them if/when you become aware of them.

"given that most of the research is around prevention of damage"

Given that aren't any preventative treatments, you're barking up the wrong tree.

"surely it's better to get tested early if you even remotely suspect there is a chance of it being Alzheimer's."

No, it's surely not.

The incidence of dementia for those aged 30-64 is about 54 per 100000. If you have a test that is 90% accurate and someone tests positive, according to Bayes you have 0.5% chance of actually having it.

Testing like that seems pointless to me.

Working: (0.9 * 0.00054) / (0.9 * 0.00054 + 0.1 * 0.99946)

Except that you are not picked from the whole population at large, but from a subset of it. Namely the subset that (weakly) believes they have dementia. This changes the incidence rate (or likelihood function) probably by at least an order of magnitude.

You're right. You have to update the probability with all the knowledge you have. Although I would say self diagnosis has a very, very high false positive rate, and if you know you're a hypochondriac that would make the probability drop, plus we don't even have a test for this that is 90% accurate. I'm not sure the difference is an order of magnitude :)

I think my point stands that it doesn't make sense to test for extremely rare diseases because of a self diagnosis.

Depends on the cost/benefit of being tested. Often non clinical early screening is a much better option.

For Alzheimer's that could be as simple as getting enough sleep for a solid 2-4 weeks. As the disease progresses really slowly waiting that time period has minimal impact, but A the pre-test is cheap and good for you, and B you rule out a lot of false positives.

> even remotely suspect there is a chance

Generally speaking, this is not a cost-effective approach to medicine.

Not even just the cost factor. You can do damage to your health from getting treatments for false positives.

There is no real test for alzheimer yet. It takes a while to establish a diagnosis. The closest thing that comes to qn actual test is the recently approved Amyvid, but then it simply shows the accumulation of Tau proteins and is not 100 percent predictive of Alzheimer.

The peanut butter test is interesting. For sufferers of early onset Alzheimer's, the range at which you can detect a smell is different between your left and right nostrils. They used Peanut Butter in this test done by the University of Florida.

https://en.wikipedia.org/wiki/Peanut_butter_test

Before someone freaks out over peanut butter, note that according to Wikipedia an attempt to duplicate these results has failed.

Now you have me worried.

At long last, the fabled credible Google symptom search result revealing that your stuffy nose is a smoking gun indicator of a fatal illness!

I feel like everyone has those symptoms from time to time

List helpfully also has "What's a typical age-related change?" under each - those are normal manifestations of each point.

Early onset Alzheimer's is extremely rare. Even if you perfectly showed all the symptoms on that list it's still unlikely you have Alzheimer's. Read up on Bayes' theorem ;)