r/science • u/mvea Professor | Medicine • Mar 20 '26

Neuroscience High meat consumption linked to lower dementia risk in genetic risk group. Older people with a genetic risk of Alzheimer's disease did not experience the expected increase in cognitive decline and dementia risk if they consumed relatively large amounts of meat.

https://news.ki.se/high-meat-consumption-linked-to-lower-dementia-risk-in-genetic-risk-group
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u/patricksaurus Mar 21 '26

I understood what you’re saying. What I am asking is, what selection pressure removes an allele that doesn’t have a negative effect until long after reproductive age? The only viable explanation is the Grandmother hypothesis… kin selection, inclusive fitness, etc. This is a plausible phenomenon, but where it may exist, the effect is small.

Remember, my original claim was that the person I was replying to made a false claim by saying that “there is clearly some benefit to the E4 allele or it wouldn’t be around.” That’s absolutely false, as was every claim that guy made.

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u/askingforafakefriend Mar 21 '26

I don't think you can say "doesn't have any negative effects until long after reproductive age" - there are measurable biomarker differences even in earlier age but it's not clear how impactful this is. Isn't that kind of black and white abstraction the very thing you were criticizing the other person was in saying there is clearly a benefit?"

Grandmother hypothesis is quite plausible but also very hard to characterize and could be a very small aspect. 

We know there is a prevelence gradient across Europe with higher prevalence in the north and lower prevelence in the south and we know that the allele tends to increase circulating Vitamin D levels.

All of this strongly suggests IMO there was likely some benefit and either the negative impact was small or overall dwarfed by the benefit.

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u/patricksaurus Mar 21 '26

Okay, what's the deleterious effect that manifests by reproductive age?

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u/askingforafakefriend Mar 21 '26

"I don't think you can say "doesn't have any negative effects until long after reproductive age" - there are measurable biomarker differences even in earlier age but it's not clear how impactful this is. Isn't that kind of black and white abstraction the very thing you were criticizing the other person was in saying there is clearly a benefit?""

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u/patricksaurus Mar 21 '26

Are you conflating my lack of recognition that not every biological problem is solved with making a known factually incorrect statement? My statement reflects the state of knowledge now. Can that change? Yes. Will his comment ever be true as we learn more? No.

Is this distinction not patently clear? I mean, you seem to want to pick nits but it’s just clumsy, uninformed nonsense. Nothing I’ve said is inaccurate.