Dementia Rate Drops Sharply, as Forecast | Hacker News Reader

Dementia Rate Drops Sharply, as Forecast

nytimes.com

117 pointsa5seo54 comments

This is great news. 60% of Dementia is due to Alzheimers whilst remaining 40% is roughly split between Vascular dementia (dementia due to mini-strokes) and Dementia with lewy bodies (a histopathological finding).

Unfortunately Alzheimers is largely a pathological diagnosis (ie. it requires a brain biopsy usually post mortem to diagnose) and I didn't dig up the british study this is largely taken from to see where they thought the decline was coming from but it is very good news and should be welcomed!

And possible good news about Alzheimers:

http://opinionator.blogs.nytimes.com/2012/09/25/bittman-is-a...

This theory that Al Zheimer is due to a form of Diabetes does not have much support from the key thought leaders currently. [Disclaimer: I worked on Al Zheimer]. For all we know, it may be a combination of several factors and not a single one.

Just for your information then, "Alzheimer" is a simple name, not a compound one and "Al" here is not a prefix (if anything, it should be broken down into "alz heimer").

Please recall what "key thought leaders" were thinking about cholesterol for previous 50 years.

I am not saying they are right. I was just adding comments on what the experts in the field are thinking about. Besides, there are some clinical trials ongoing to treat "Brain Diabetes" as a way to fight Al Zheimer but nobody expects much from them, including investors. It's probably not that simple.

From "investors" word, I assume they are trying to treat it by adding medications? What about removing carbs? Though, investors would be really disappointed..

"Removing carbs"... talk about pseudo-science...

Yeah because dietary modification is no way to treat a disease [1] coughPKUcough

[1]- http://en.m.wikipedia.org/wiki/Phenylketonuria#Treatment

Oh yeah, and diabetes also? No sales - no science? Looong way to go..

Why are you spelling it like that?

So that people ask questions :) No, simple mistake. But I can't edit my post anymore.

One of the most fascinating pieces I read about dementia care was also in the NY Times about life prisoners.

(http://www.nytimes.com/2012/02/26/health/dealing-with-dement...)

Wow, that was moving.

Hopefully this is true, I feel like the studies were not thorough enough to conclude conclusively that Dementia is declining, for example the study in Denmark had relatively moderate to small numbers and takes people at different ages (93 and 95, perhaps people with Dementia likely die before 95 for example). The British study seems better, but still 56% of people declining is kind of high.

In either case, logically this seems fairly strait forward and these studies do provide some insight, so good news! I hope there's a similar study done in the U.S.

I wonder how much attribution can be given to the thought that many people keep their minds more active now with various forms of entertainment like games, smartphones, books, puzzles, etc.

Is there any evidence that that affects things either way? (Genuinely curious)

There is absolutely evidence that mental acuity is protective against Alzheimer's.

From [1] Education > 15 years (cf. <12) has the lowest relative risk (0.48) of developing Alzheimer's of all investigated interventions

Patterson, C. et al. CMAJ 2008;178:548-556 (for those that can, DOI: 10.1503/cmaj.070796 )

That's good, thanks, but it doesn't really address the original question regarding games for example. Also what if dementia already has some effects early in life, just more subtle. So for example early stages could be more difficulty concentrating, variations in attention, or greater difficulty in internalizing ideas, memorization, or recall. Then those who would later show typical symptoms of dementia later in life would be more likely to end education early just because they had more difficulty with it than their peers.

Hi Mzs, thats a really good question and you're right I don't directly address it. Basically it's impossible to examine for that at the moment because 'games' etc would rely on a person's recall of, say, how much they did the cross-word, that sort of thing whereas education is verifiable and, in this case, statistically meaningful.

Regarding onset of dementia.

There are early-onset dementias that can start from the late 40's to 60s. These are usually of a genetic variant (For example, 2 copies of ApoE4 gene, Amyloid Precursor Protein or a presenilin mutation, or Down's syndrome). Diabetes is a big risk factor as well.

There are also a number of dementias that are of early onset that are not Alzheimer's such as Frontotemporal dementia and Semantic Dementia which are awful diseases and it's terrible to watch patients so young with such severe pathology.

>Also what if dementia already has some effects early in life, just more subtle.

Just to focus on the most common dementia, Alzheimer's - We know that it doesn't have more subtle effects early on. When you start to develop it, you start to develop it. The following things are the features of Alzheimer's, in order of progression:

- Memory

o Impaired anterograde episodic memory

o delayed recall of stories

o ‘Sparing’ of Working memory

- Attentional and executive deficits

o poor concentration

- Language and Knowledge

o Impaired semantics

- Visuospatial and perceptual disabilities

But It definitely is not apparent so early for example in people at 20 or 30 years of age.

We know this because brain biopsies from post mortems of young people don't show the neuronal loss, amyloid plaques and 'tombsones' of Tau protein tangles on histology which is pathognomonic of the disease.

In fact, Education seems to be so important at preventing the march of the disease not because higher levels of brain activity somehow decrease deposition of the characteristic histology findings, but because increased education increases so-called 'cognitive reserve', meaning that even when the damage starts to occur, the person is still able to function at such a high level because the decline in global cognitive capabilities has not yet been so great that the characteristic signs and symptoms have begun to manifest.

Could you argue cause vs effect with regard to education and cognitive reserve? Sure, and I haven't examined the data closely enough with regard to education to know how or if they controlled for it. However I have read extensively from the original literature with regard to the origins and pathogenesis of the disease and trust that something that is trumpeted at being a major factor in delaying the development of AD, by way of the quality of the reporting literature (Lancet, NEJM, Nature and Nature Medicine) to not have been missed after extensive peer review over the course of several decades (?the argument from authority? I feel it is well enough established to be fact)

Thanks, I did not know about the results from biopsies of young and that was a good point about the quality of data just asking about how much people remember doing something like puzzles and games. I really enjoy this site thanks to the thoughtful comments, have a good one.

I think that is http://www.cmaj.ca/cgi/content-nw/full/178/5/548

I'm not sure about scientific evidence, but it's almost the case you don't need scientific evidence to know that keeping an active mind severely mitigates dementia. I think there's a lot of research regarding Alzheimer's, but this kind of research has huge timeframes which make hard to draw good conclusions from because of experimental design limitations.

> but it's almost the case you don't need scientific evidence to know that keeping an active mind severely mitigates dementia

What makes you say that? There's plenty of medical phenomena that exist / don't exist despite being logically appealing.

I meant there's limited evidence (see robbiep's post), but it seems as intuitive as 'exercise makes you physically stronger', although I've never read scientific evidence on that.

There is almost unlimited empirical evidence for exercise making one stronger, so I don't see how that is intuitive, a better term is common knowledge. Is it intuitive that eye exercises improve age related visual decline? (It doesn't, just an example)

"you don't need scientific evidence to know"

"but it seems as intuitive"

Knowledge can come only from reasoning based upon observations. You cannot know anything by intuition. You can believe your intuitions and feel that they must be true, but you cannot know they are true.

"Exercise makes you physically stronger" isn't intuitive at all. Are you stronger after you exercise? No! You're weaker than when you started. Rest makes you stronger, short-term. The increase in strength from exercise happens over a very long period of time and is tough to correlate with the exercise unless you study it fairly deeply. Furthermore, non-living objects almost universally decrease in strength from exercise.

Without actually studying the question in some detail, I don't see how one could intuitively conclude that exercise increases physical strength.

If one phrase could sum up human (and probably all living creatures') physiology it would be, "Use it or lose it."

We are adapted to conserve resources so anything that requires resources to maintain will be reduced if we don't actively use it. Muscle tissue, brain cells, you name it if we don't use it it will atrophy.

Yes, but we know this from studying it, not because it's "intuitive".

Intuitive is just a synonym for "similar to previous experiences." Anyone who has regularly exercised or played a sport or even a musical instrument and then stopped knows about use it or lose it we even have a term for it, "being a little rusty."

And anyone who's exerted themselves physically for more than a few minutes at a time knows that the more you do it, the more tired and weak you become (short term). If "intuition" supports both, it says nothing.

I feel you are being disingenuous. We all have enough long-term memory to discern patterns beyond the short term and classify them as such.

Feel what you like, I don't care.

There are plenty of examples, both in nature and in the human body, of "use it or lose it" and "use it up and it's gone".

Because we are human bodies, with all the intuition and wisdom that entails.

It's less intuition and wisdom than many people think; gut feelings for example should be examined, though they're often telling you something important.

I think it's reasonable to infer that, as we are human bodies, we would know how to make ourselves stronger. The idea that mental exercise keeps the brain sharp comes from a similar intuition; it is not surprising to see it confirmed through study.

Why, exactly, would it be reasonable to infer that we would know how to make ourselves stronger, just because our bodies are where we live?

Sure, you could say that mental exercise keeping the brain shark comes from intuition. And I could say that it's intuitive that mental exercise depletes the brain and makes things worse. I don't see how you decide which one is right without going out and studying it.

One cannot, of course. It would be somewhat fatuous to be surprised that exercise makes one stronger, when it has been advocated for thousands of years as the (only) method for doing so. This is as true of mental exercise as it is of physical.

It is not typical of our community norms to downvote reasonable arguments you disagree with. Just FYI.

I'm not talking about "surprised" or anything. I merely object to "intuitive", both in that I don't see how intuition supports this, and I don't think intuition is worth anything here anyway.

Don't assume the person downvoting you is the person you're replying to.

Indeed, that is impossible ^_^ It was an aside for whomever did so. Intuition is not a particularly valuable or precise word, is it.

In the field, what you are referring to is described as "cognitive reserve". People with higher educations levels or who have a more active lifestyle suffer less from the earlier stages of dementia, because they are better able to develop coping strategies.

So, it is similar to exercise in the way that if you are fitter, then you can better weather adverse events. However, cognitive reserve doesn't delay the underlying progress of Alzheimer's disease.

I strongly distrust this study because of participant "self-selection bias". 80% of approached subjects declined to participate in the tests. There is too much probability, that those people who experience onset of dementia would decide to not participate in such study, especially now, when privacy is getting NSA-ed and all data about you is going to affect your google search, targeting, re-targeting and your insurance rate

While I certainly agree with your suggestion that there might be self-selection bias in play (as commented on in the article), to suggest that the subjects were concerned about the NSA or Google is ridiculous. The study was undertaken between 1984 and 1994. Google didn't exist and the vast majority of the population had no internet access. The idea of electronic data privacy had probably not even occurred to most approached. I would be surprised if more than a handful of those approached (all aged above 65 in 1994) even owned a computer.

Please don't hijack every comment thread with irrelevent complaints about the NSA.

Ok, I did not pay attention to the timespan, thought it is much more recent study. This however, doesn't alter anything, people today are no more willing to self-reveal fatal/terminal/disabling ilnesses, or even to accept having one - than 100 years ago

I suspect a statistical error.

Are you suspecting any particular analytic error, or are you just expressing an unwillingness to believe in the conclusion without regard for the strength of the evidence?

A drop of more than 25% would be sensational indeed. This is highly implausible. The article even hints at "methodological problems" in previous studies. BTW, medical studies in general are known to be prone to methodological errors.

I work in this area, and I would be inclined to agree with you. The most likely cause of this result is methodological variance. Even if that can be formally excluded (which is unlikely), the next most likely reason (alluded to in the article) is that dementia is one aspect of ageing, and that if people are healthier for longer then the effects of ageing are less pronounced in the younger elderly. Thus it would have no impact on the eventual likelihood of dementia for an individual, just that it might occur later than it otherwise would.

I suspect pure methodological one. Theoretical test for biological diagnosis seems very, very weak evidence to me. They are basically comparing two differently educated societies, not two sets of bodies.

It's important to note that none of this decline was attributed to medications which are meant to manage the symptoms. These medications are, IMO, largely useless.

Some studies show that the medications efficiency is variable, but in college I did a long term study with elder people with dementia, and guess what was the conclusion? The ones that did not take meds had bigger cognitive losses, and the ones that did take meds on early dementia stages had a smaller loss.

Unleaded gasoline.

Leaded gasoline potentially affected at most a few generations in the 20th century. Do we see a spike in dementia correlated with the years that leaded gasoline was used?

Just conjecture -- but the ww2 generation would have had the most lifetime exposure to leaded gasoline. They're dying off in increasing numbers.

Subsequent generations may have had less exposure due to suburbanization and the banning of leaded gas.

This was my thought too. From a cursory look at the ages in this study I'm thinking it's not the cause here at least? I may be wrong.

I'm still very curious is Alzheimer's is caused by something environmental? I've heard aluminum suggested but I haven't seen anything conclusive. (And I can't find antacids that don't include aluminum!)

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