Could an Eye Doctor Diagnose Alzheimer’s Before You Have Symptoms? | Hacker News Reader

Could an Eye Doctor Diagnose Alzheimer’s Before You Have Symptoms?

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76 pointsGys32 comments

Not mentioned is the problem with prions and eye examinations as a possible infection route:

https://www.nih.gov/news-events/news-releases/eyes-cjd-patie...

Definitely interested in this. I had my genome sequenced at 23andme and they say I am at a higher risk for early onset Alzheimer's (My parents and grandparents were/are fine) because I have the two mutations they test for.

Just last year I was diagnosed with glaucoma, at the ripe age of 32. So I go to the eye doctor somewhat regularly now. Wonder if this is something I can start keeping track of, for science, or something.

> sequenced at 23andme

Be careful. My wife, a geneticist, calls 23andme "for entertainment purposes only."

In this specific case, they do test for the ApoE gene which can you a 20x higher chance of getting Alzheimer's https://en.wikipedia.org/wiki/Apolipoprotein_E#Alzheimer's_d...

20x more is not a sure thing, but for a disease like Alzheimer's that is already pretty common (e.g. we're not talking about risk increasing from 0.01% to 0.2%) it's more meaningful than just for entertainment purposes.

I agree with your wife that for most people their 23andme results will be nothing more than entertainment, but there are a handful of truly meaningful things it can find.

I'd be way too concerned that results of genetic tests could turn out as self-fulfilling prophecies that I'd take one and have the results reported back to me. Might be nice if it were decoupled from you, e.g. by sending the results to a close relative or your doctor who then knows what to look out for.

Random datapoint of course, but you don't use nasal steroids do you?

Medicine free except for Vyzulta eye drops for my glaucoma.

I've read that before there is tissue decay, which this test would be for, there's a preceeding biochemical phase: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819840/figure/...

The title is kinda wrong. Loss of blood vessel is just yet another symptom.

Yes, however, finding an early symptom, particularly a decade early, would be an incredible find.

If we could detect pancreatic cancer early, for example, would could go from a 7% survival to 90% rate.

Can we not detect it early? Or do we just not run the tests?

Like if everyone got regular MRI scans (I know, expensive, but it's a hypothetical) could we do the same thing?

As far as I understand it, the area of the pancreas can often be difficult to detect cancer in- and particularly the area has a lot of space for metastasis.(I’m not a trained medical professional so if my words are contradicted by anyone who is, please ignore me entirely.)

I’m under the impression MRI scans have two main issues with them:

1. A trained radiologist can still miss small tumors, and it is in fact quite easy to miss them. The body is complicated and all sort stuff of weirdnesses can occur that are not harmful.(eg. Benign tumors)

2. It is possible that the discovery of a tumor doesn’t mean cancer. This was a debate in breast cancer treatments- a lot of heartache and suffering can occur from a cancer scare and there has been existing controversy regarding early testing given this.

3. Radiation from breast cancer scans can cause the breast cancer in the first place:

https://annals.org/aim/fullarticle/2480762/radiation-induced...

That study is entirely based off simulation with the ultimate data being derived from survivors from Hiroshima and Nagasaki bonbings. We do not categorically know if there is a linear, no threshhold relationship between diagnostic radiation dose and cancer induction or if there is a threshhold dose below which radiation dose is “safe”. We also don’t know if low-level radiation is potentially beneficial (radiation Hormesis hypothesis).

That’s a lot of words to say, take that paper with a huge grain of salt.

Was the linear-no-threshold model not basically disproven by a study on people who lived in buildings built with steel scavenged from the ruins of Hiroshima or Nagasaki and therefore in an environment with elevated radioactive background levels. They showed lower incidence of cancer if I remember correctly?

Thank you, that's a fair point. I don't think mammograms are low-dosage radiation, are they?

>take that paper with a huge grain of salt.

Too much salt isn't healthy either ;)

>2. It is possible that the discovery of a tumor doesn’t mean cancer. This was a debate in breast cancer treatments- a lot of heartache and suffering can occur from a cancer scare and there has been existing controversy regarding early testing given this.

The same thing is true with thyroid tumors. A lot of people got their thyroids removed because they had tumors called "thyroid cancer", and now the consensus is that these tumors, while not completely benign, are so slow-growing that it's not worth it to remove them in most cases. Many times, people were only found to have these tumors after they had died (of something else).

Could a reason be that the tests are not accurate enough to avoid the "false positive paradox" of the "base rate fallacy"?

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

> Like if everyone got regular MRI scans

Actually, I think that scientists are wondering about this as well [1] [2]. If they determine that regular whole-body MRI checkups are a good idea, I guess that demand for cheap MRI machines will surge. People who'd invested into industrialized production lines for MRI machines would make a lot of money. Possible startup idea?

[1]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4362601/

[2]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6248944/

One of the challenges with pancreatic cancer is that the tumours may be invasive while they are small and / or undetectable. In many cases when the patient is symptomatic and does not have any detectable metastasis they will still end up with mets after surgical resection of the primary tumour.

And, sadly, if we could detect Alzheimer's a decade early, it would go from a 0% survival rate to a 0% survival rate.

Early detection would still be valuable for other reasons, though.

Captain pedantic here, but it's a sign, not a symptom.

My med school mnemonic: Patients report symptoms, then doctors see signs.

Anyone in the field know if lattice degeneration would be considered 'loss of blood vessels in the retina' this study is looking for?

Type 3 diabetes.

I'm not sure why you're being downvoted, other than perhaps the terseness of your response. There is research that hypothesizes that Alzheimer's is like diabetes in that it manifests itself as a dysfunction of insulin/glucose regulation.

Yes, the symptom described in the article is congruent with the diabetic theory because loss of small blood vessels is also a symptom of diabetes.

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