
Patterns of Regional Cerebral Blood Flow as a Function of Obesity in Adults - InInteraction
https://www.iospress.nl/ios_news/body-weight-has-surprising-alarming-impact-on-brain-function/
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wrkronmiller
Worth noting that the first author is CEO of this clinic [0]:
[https://www.amenclinics.com](https://www.amenclinics.com)

> At Amen Clinics, it all starts with you. We look at your biological,
> psychological, social and spiritual influences to get a complete picture of
> who you are as a person. With life coaching, nutritional guidance and
> personalized therapy, we provide the tools you need to feel confident,
> complete and hopeful for the future. We are dedicated to helping you find
> the answer to you.

0: [https://www.j-alz.com/manuscript-
disclosures/20-0655r2](https://www.j-alz.com/manuscript-disclosures/20-0655r2)

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alextheparrot
From reading the proof, it seems the authors are mainly focused on “linking”
or showing correlation, not causation.

Part of me wonders about the directionality of causation here (If we assumed
one existed). One could argue the hippocampus, which from my recollection is
involved in inhibiting impulsive behavior, has a clear path to being a
causative agent for obesity. Distinguishing between the two narratives of
“Being overweight inhibits brain function” versus “Differences in part of
brain controlling impulses leads to weight differences” is important to
resolving it, as it is easier to imagine treatment regimens to combat weight
more than brain blood flow.

It is also completely possible these two variables do not affect each other,
but are correlated. That’s useful still, because it means we may be able to
use body weight increases as an inferred marker for the brain changes.

It would be incredibly interesting if the story of Alzheimer’s transformed
more into “Same factor may be causing both America’s obesity increases as well
as Alzheimer’s cases”

Edit: Updated this a few times while reading the original paper

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CyberDildonics
Or maybe fructose intake and absorption correlates to both obesity and
cognitive function.

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alextheparrot
I fell into the same over-reaching trap I was critiquing, which is a bit
funny, but I agree they could be caused by the same thing and correlated
because of that as well.

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sjmj3us
I'm suspecious of this because the author is Dr Daniel Amen. Who makes a lot
of money from brain scans that are considered suspect by many medical
professionals. I would be inclined to withhold judgement until some more
objective group corroborates this.

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kevin_thibedeau
Anybody with infomercials on PBS should be regarded with suspicion.

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gpm
Worth noting that the vast majority of the participants in this study had
existing mental disorders, 57% "generalized anxiety", 51% ADHD, 17% Major
Depression, 7.4% Bipolar Disorder, and so on.

The authors claim (but don't show their work) that adjusting for these factors
did not change the statistical significance of the relationship, but it does
still mean this isn't exactly a representative sample of the population.

Very interesting that underweight people generally have more blood flow than
"normal" weight people, though if you dive into the supplementary data that
doesn't hold for every region of the brain studied (and the general trend
seems to hold in all regions studied).

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jeffreyrogers
Presumably this has more to do with body composition/diet than weight, right?
I.e. a muscular person with a healthy diet and normal amount of body fat but
with high BMI is not at higher risk. (I'm not debating the merits of using
BMI, I realize it is a useful proxy).

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acvny
Correct, but this is so rare that can be ignored.

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Grimm1
Huh what? Any high muscle athletic person would hit this.

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bjo590
What percentage of males in the US with a BMI over 30 (obese) have a body fat
percentage less than 25? My guess is less than 3%, but I don't have data to
back it up. When studying populations you can ignore these outliers. It's well
known that BMI works well for populations but can fail when looking at
individual health.

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codyswann
Checking in - MBI over 30. Body Fat Percentage less than 10. It's not rare in
my circles

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nradov
The point is that individuals with high BMI and low body fat are rare in the
general population, and can be ignored as statistical noise in most broad
scientific studies. Your circles would only be relevant for studies
specifically targeting body builders.

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Grimm1
They're not though, what? I want to see you back up this claim with evidence
before passing it off as fact.

Edit: It is fairly easy to be < 25% body fat with normal musculature that
accompanies normal weight lifting and cardio routines 4 times a week. That
will get you to a BMI +30 at 5"10 +

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dade_
8% difference from normal to obese seems expected, not alarming. I don’t see
anything in the study that factors for exercise though it is the health advice
provided in the article.

‘Regular exercise linked to higher blood flow in brain’ seems a more
appropriate, not dramatized headline. Thank you Captain Obvious.

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bryanrasmussen
As Alzheimer's and most other neural degenerative diseases progress body
weight decreases rapidly.

I would also think, based on some people with eating disorders I've observed
where the weight decreased, that a very low body weight also might have an
alarming impact on brain function - not sure how surprising it would be and if
really a cause and not a correlation. Probably just a correlation.

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asutekku
Clickbaity title aside (seriously, that’s the original press release title),
pretty damning results. Basically a higher BMI means a higher probability to
get an alzheimer’s disease.

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waihtis
Wonder if this applies the same for both ”muscular” and ”fat”?

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antidaily
Probably don’t have same blood flow issues being muscular as being fat.

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xdavidliu
can you provide a citation?

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sparrish
I have a hard time believing this study. Anecdotally - I have about 10 years
experience in assisted living homes (read early stages for dementia and
Alzheimer's) and I can't think of a single dementia resident that wasn't thin
as a rail. I also can't recall a single overweight resident that had dementia.
Grain of salt and all that.

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exabrial
> FunctionHigher BMI is linked to decreased cerebral blood flow

Most people equate weight=high BMI, so the title is probably accurate for a
casual audience but it's important to note the study is actually looking at
BMI.

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bostonpete
BMI is linearly related to weight, so for a given person, whose height is
fixed, it's appropriate to think of this as the impact of weight....

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seibelj
The media has almost entirely ignored how the majority of young people who
died of Covid were obese. Two days ago the NYT finally acknowledged this as a
risk factor despite it being obvious to anyone paying attention
[https://www.nytimes.com/2020/08/14/health/covid-19-obesity.h...](https://www.nytimes.com/2020/08/14/health/covid-19-obesity.html)

Being fat is an enormous risk factor for dying of Covid, but instead of a
giant “Get Out and Jog” campaign we are just supposed to hunker down inside
and pray for a vaccine.

Being fat is a sign of generally poor health. It hurts your immune system. It
reduces your quality of life. It has ripple effects to the rest of your body.

The fat positivity movement is one of the worst movements ever to exist. There
is nothing positive about being fat. It is only negative.

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mrfusion
If I was in charge during this I would have done a huge get healthy campaign.
Vitamin d for all, free gym memberships and park fees, healthy food campaign.
(Plus protecting nursing homes)

It would let people feel like they’re doing something to fight the disease. It
would bring us positivity instead of negativity, and the health improvements
would pay dividends for years.

Oh also a massive volunteer effort for healthy people to deliver food and
medicine to the elderly and vulnerable.

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Someone1234
Sounds like if you were in charge you would have done the opposite of social
distancing (e.g. free gym/parks, volunteers visiting tons of people's homes,
etc). This seems like a strategy that could increase the spread significantly.

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mrfusion
Interesting point. The volunteers would have to be super careful. I’d envision
leaving the food outside the door.

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narag
That's exactly what has been done in Madrid. Council organized free meals for
vulnerable people, but there were many individuals that just volunteered for
their neighbours.

My mother and his husband received several offers from young couples in the
block to go buying groceries or make any other errands and leave them outside
the door.

The vitamin D and C were sent by me through Amazon :)

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mrfusion
It’s interesting that high blood pressure is linked to poor brain health
outcomes (AFAIK).

Maybe high blood pressure is the body trying to compensate for reduced blood
flow?

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treeman79
IHH. High inter cranial pressure is horrible on cognitive abilities.

If I get a spike, it can take a week to be back to normal brain function.

It puts a lot of pressure on the veins, taking them close to bursting. Body
needs time to heal.

One insidious part is that exercise makes it worse. So if you exercise,
pressure spikes, you need a week or two to recover.

I spent years trying to push through exhaustion, but everytime I worked out I
would need weeks to recover. So I made little progress.

Proper diagnosis and medication suddenly enabled me to exercise daily. Massive
life changer.

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nradov
For most people, exercise _reduces_ blood pressure (post exercise
hypotension).

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fortran77
There are many published, referenced papers on this:

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651104/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651104/)

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737453/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4737453/)

etc.

However, this is a topic that we are not allowed to discuss here.

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mrfusion
I wish studies like these would look at apoe4 status.

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ta17711771
Oxygenation is important.

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xwdv
In layman's terms, the fatter you get the dumber you get.

A layman would also look at a country like say, America, where obesity has
been on the rise for decades, and the population seems to get increasingly
uneducated and insular, and deduce this to be true.

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alextheparrot
The study observed a correlation, please don’t put forward a causative
narrative when these could just be correlated or causative in a way different
from the way you propose.

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xwdv
Given that obesity is the cause of a whole host of ailments, I’d say it’s fine
to play it fast and loose and put forward this narrative.

Is it scientifically rigorous? No, but sometimes there isn’t enough time for
rigor and you’re better of making an educated guess than having no conclusion
at all.

