Being Overweight Reduces Dementia Risk

jones_supa writes Being overweight cuts the risk of dementia, according to the largest and most precise investigation into the relationship (abstract). The researchers were surprised by the findings, which run contrary to current health advice. The team at Oxon Epidemiology and the London School of Hygiene and Tropical Medicine analyzed medical records from 2 million people aged 55 on average, for up to two decades. Their most conservative analysis showed underweight people had a 39% greater risk of dementia compared with being a normal healthy weight. But those who were overweight had an 18% reduction in dementia, and the figure was 24% reduction for the obese. Any explanation for the protective effect is distinctly lacking. There are some ideas that vitamin D and E deficiencies contribute to dementia and they may be less common in those eating more. Be it any way, let's still not forget that heart disease, stroke, diabetes, some cancers and other diseases are all linked to a bigger waistline. Maybe being slightly overweight is the optimum to strike, if the recent study is to be followed.

Comments

Easy explanation

[jawtheshark]

Easy explanation: They die before they develop dementia...

Re:Easy explanation

[Mr D from 63]

This explains why we never see fat serial killers in movies.

Re:Easy explanation

[ShanghaiBill]

Easy explanation: They die before they develop dementia...

Another easy explanation is that the causation goes the other way: People with dementia are less likely to gain weight. There could be many reasons they eat less: less cravings, less ability to prepare food, less social interaction at meals, or just forgetting to eat. They are also more likely to smoke, which reduces appetite.

Re:Easy explanation

[CrimsonAvenger]

Another easy explanation is that the causation goes the other way: People with dementia are less likely to gain weight.

Well, that would work if they studied people with dementia to determine their weight, instead of studying people without dementia, then waiting nine years to see if they developed dementia...

Re:Easy explanation

[pepty]

Our cohort of 1958191 people from UK general practices had a median age at baseline of 55 years (IQR 45–66) and a median follow-up of 91 years (IQR 63–126). Dementia occurred in 45507 people, at a rate of 24 cases per 1000 person-years. Compared with people of a healthy weight, underweight people (BMI 40 kg/m2) having a 29% lower (95% CI 22–36) dementia risk than people of a healthy weight. These patterns persisted throughout two decades of follow-up, after adjustment for potential confounders and allowance for the J-shape association of BMI with mortality.

Re:Easy explanation

[pigiron]

Correlation may imply causation. This inspires scientists to develop testable hypotheses that might prove or disprove a connection between the correlated data.

Re:Easy explanation

[Anonymous Coward]

Right accept that people who are overweight or mildly obese actually live longer:

http://www.npr.org/blogs/healt...

I like how the article you linked to already has a refutation of this claim within it.

One of the experts who takes issue with Flegal's conclusions is epidemiologist Walter Willett of the Harvard School of Public Health. He has read her new paper and says he's not buying it.

"This study is really a pile of rubbish, and no one should waste their time reading it," he says.

Willett says it's not helpful to look simply at how body mass indexes, or BMIs, influence the risk of premature death, as this paper did, without knowing something about people's health or fitness. Some people are thin because they're ill, so of course they're at higher risk of dying. The study doesn't tease this apart.

Also, he says the analysis doesn't address the bigger, more important issues of quality of life. If an overweight person does live longer — is he or she living with chronic diseases?

"We have a huge amount of other literature showing that people who gain weight or are overweight have increased risk of diabetes, heart disease, stroke, many cancers and many other conditions," Willett says.

Re:Easy explanation

[ShanghaiBill]

Well, that would work if they studied people with dementia to determine their weight, instead of studying people without dementia, then waiting nine years to see if they developed dementia...

Dementia doesn't work that way. It is not like the flu, where you are just fine until you "catch" it. Dementia creeps up on you. So even nine years earlier, there were almost certainly already behavior differences that would be amplified as the disease progressed. School essays written decades earlier, by people that latter suffered from dementia, are less creative and more likely to be just a list of statements, with less emotion and self-reflection. So it is likely that eating habits could also be affected years before the symptoms become obvious.

Re:Easy explanation

[Impy the Impiuos Imp]

Too much blind guessing. Here's the correct answer.

The error everyone makes in assuming that because it's bad for heart disease, it's bad for everything.

Obesity is a problem primarily because of cardiovascular reasons, like heart attack and stroke. Otherwise it's loaded with nutrition and calories. This probably explains why "overweight" (though not obese) are the longest-lived segment of society. Thinner people are running more on empty, leading to under-performing immune systems and healing.

That's where I'd start to look anyway.

And on top of all this, high fat content is known to help neurons function in cases with epilepsy, so again it's not a surprise here.

Re:Easy explanation

[David_Hart]

Too much blind guessing. Here's the correct answer.

The error everyone makes in assuming that because it's bad for heart disease, it's bad for everything.

Obesity is a problem primarily because of cardiovascular reasons, like heart attack and stroke. Otherwise it's loaded with nutrition and calories. This probably explains why "overweight" (though not obese) are the longest-lived segment of society. Thinner people are running more on empty, leading to under-performing immune systems and healing.

That's where I'd start to look anyway.

And on top of all this, high fat content is known to help neurons function in cases with epilepsy, so again it's not a surprise here.

There was also a study of elderly done a while back, I think that it was on 60 minutes, that found that elderly people who were a bit overweight tended to live longer. One of the possible reasons was that when they got sick, injured, etc. they had body reserves that would help them heal and get better.

Re:Easy explanation

[ShanghaiBill]

Any more info on the "School essays written decades earlier ...? Like links?

Here you go.

From the reference: it was found that an essay's lack of linguistic density (e.g., complexity, vivacity, fluency) functioned as a significant predictor of its author's risk for developing Alzheimer's disease in old age. ... Roughly 80% of nuns whose writing was measured as lacking in linguistic density went on to develop Alzheimer's disease in old age; meanwhile, of those whose writing was not lacking, only 10% later developed the disease. Overall, findings of the Nun Study suggest "that traits in early, mid, and late life have strong relationships with the risk of Alzheimer's disease, as well as the mental and cognitive disabilities of old age."

mode of death

[Anonymous Coward]

diabetes, heart failure, stroke & cancer are all better deaths than alzheimer's(or any of the neurodegenerative illnesses)

Re: mode of death

[pepty]

but I bet it isn't that bad on the inside.

Except that for many people they are very aware of what's happening and what they are losing. They are intensely angry and frustrated when they lose the ability to verbalize all (or part) of what they are thinking and then it gets worse when they can no longer hold onto the complete thought. Plus as they lose executive function it is harder to control that anger and frustration. Sure, some folks have a stroke and seem to enter a second childhood, but for many it's a living hell of isolation from everyone you know - including yourself.

Re: mode of death

[Ol Olsoc]

I've got to disagree with you there chief. Dementia and Alzheimer's might seem terrible from the outside, but I bet it isn't that bad on the inside.

You need to visit a nursing home some time. Where my mother in law was housed had lots of dementia patients. A lot of them cried all the time, some were angry - in at least one case, the fellow was violent, and they eventually had to send him to a more restrictive facility. Anyhow my mother in law was a crier, I can't imagine anyone spending time around her and thinking dementia isn't that bad. I knew one "happy" dementia patient.

Plus, it isn't just wandering around being a little confused. As your brain shuts down your cognitive ability, it is also bitching up your internal organs, everything gets messed up, and you die slowly, usually over around ten years.

Cancer on the other hand is pretty terrible. Diabetes isn't a cake walk either. And all four of those conditions can kill you decades before a neurodegenerative disease is likely to strike.

My father died of cancer. He had the benefit of pain killers, and it was fairly quick. And he had his mind. We had intelligent conversations up to the evening he died.

I'd much rather die at 90 from Alzheimer's than at 40 from a heart attack.

Perhaps if you see a few family members take ten years or so to die, spending every waking moment crying, or some times having to be restrained because they are violent toward other patients, or all calm on haldol because otherwise they spend their days screaming at the bats flying around in the room, you might willingly trade ten years of life for a happier ending.

The worst thing is that we even try to extend their lives as their internal organs are going haywire, they are on drugs to keep themselves and other patients safe.

I long ago decided that if there is a hell, it resembles nothing as much as a dementia ward.

Re: mode of death

[hairyfeet]

Insightful? Really mods? As someone whose father in law has it let me clue you in on something pal, they can literally feel their minds going and can't put their fingers on WHAT is going wrong, just that something IS going wrong. Result? Either they cry as another guy said or even more likely they get ANGRY and stay that way for the rest of their days.

Picture a wounded animal, snapping at those around it because it is in pain and cannot help itself...THAT sounds like fun to you? I know you are probably basing it on vids of Douglas Adams.....DON'T DO THAT, Adams had a VERY rare form that attacks the back of the brain instead of the front and center, that is extremely rare, for the other 99.9995% it attacks the front and center and while you may end up as nothing but a quietly laying lump that takes a very loooong time to get there and for the rest? You are dangerous (because you refuse to accept you can't do the things you always did), mad (because you know you aren't right but cannot create the words to express it which is frustrating as hell), and you often refuse to have a damned thing to do and will outright attack those that try to help you like your family because you cannot recognize them no more except for a vague feeling that leaves you uneasy...and THAT sounds like its "not bad" on the inside?

Personally I'd rather eat a damned bullet than end up like that, at least it would be over quickly.

Re:Only correlation has been established.

[beelsebob]

Actually, studies tend to show that being slightly over weight reduces all-cause mortality compared to "normal".

http://www.ncbi.nlm.nih.gov/pu...

Your all-cause mortality rate for overweight, and grade-1 obese are roughly 0.95 times that for "normal" weight. However, being grade-2 obese or more is associated with a sudden, very rapid increase in mortality rate.

Basically, being slightly overweight isn't bad, and may even be pretty good. Being more-than-slightly overweight is really really really bad though.

My wife says ...

[PPH]

... women who put on some extra weight tend to live longer than the men who point it out.

High BMI does NOT mean overweight!

[TimSSG]

BMI is NOT a good way to judge over and underweight. Tim S.

Re:Easy explanation: not for competent researchers

[seawall]

  A competent epidemiologist would control for the "They die before they develop dementia" effect.

  Given this is a peer reviewed study I think it hugely likely they controlled for that.