Study shows dementia more common in older adults with vision issues | Hacker News Reader

Study shows dementia more common in older adults with vision issues

michiganmedicine.org

142 pointselorant77 comments

The language in this article is a bit confusing to me:

> "In a sample of nearly 3,000 older adults who took vision tests and cognitive tests during home visits, the risk of dementia was much higher among those with eyesight problems – including those who weren’t able to see well even when they were wearing their usual eyeglasses or contact lenses."

Is this saying that people even with CORRECTED vision problems still have the same dementia risks? So many comments in this thread are linking dementia to lack of visual stimulus. But if the risks apply even when the vision impairment is corrected, then doesn't imply some deeper relationship?

I suppose you could argue that corrected vision isn't corrected 24/7, with glasses or contacts that are periodically removed. But that point really doesn't feel satisfying.

LASIK surgery has been widely popular for just over 20 years now. I'd be interested to see how permanently corrected vision factored into this study, and how the results might change over time as we have more elderly who underwent LASIK at younger ages.

I would speculate they are measuring the decline in visual processing in the brain and optic nerve in this case, not the impactful of poor sight on cognitive decline.

I read it differently. It sounds to me like it’s saying that it was people “who weren’t able to see well when they were using their prescription lenses.” As in, they have prescription lenses, but their vision is not actually corrected.

I agree, and to me it hints at a couple of possibilities...

Perhaps they are receiving sub-standard vision care (and are thus unable to get updated eyeglass prescriptions, cataract surgery, etc), and this might be associated with other forms of sub-standard care.

Or perhaps a person suffering from dementia is less likely to notice and/or less able to pursue treatment for their own declining vision...

This is almost certainly referring to seniors who continued to wear corrective lenses but had cataracts hindering their vision, as is extremely common in old age. While LASIK can be an excellent long-term solution for myopia, it is not a preventative measure against cataracts.

Cataracts are fairly treatable, no?

Judging by my family some older people are reluctant to have doctors poking about in their eyes.

They straight up replace the lens of your eyeball with a plastic one, and as result you can often see better than ever, without glasses. That was the outcome for my dad, anyway.

My dad's side of the family has eye problems: myopia, glaucoma, detached retina, and wet macular degeneration. Hoping my mom's genes spare me the worst of it.

Yes, depending on your access to treatment.

I assumed the article meant that this was people whose vision had changed (so no longer had correct prescription) or cataracts.

> LASIK surgery has been widely popular for just over 20 years now. I'd be interested to see how permanently corrected vision factored into this study, and how the results might change over time as we have more elderly who underwent LASIK at younger ages.

Lasik can correct an astigmatism or other curvature problem but cannot do anything about presbyopia (which by definition affects older people) as that is a loss of ability to change the shape of the eyeball. That's why older people need reading glasses even if they otherwise still have 20/20 vision.

You don't have to be that "old". Late 30's it is possible

Obstetricians call having a first baby at 35 "geriatric primagravida" too...

From the conclusion of the study the article cites:

> In this survey study, all types of objectively measured VI were associated with a higher dementia prevalence. As most VI is preventable, prioritizing vision health may be important for optimizing cognitive function.

In other words, the association is dementia and uncorrected visual impairment.

EDIT: I'll add that the study does not show causality. Even people like myself who are well aware that correlation != causality often still assume it does. It doesn't help that the authors themselves imply that correcting VI would ward off dementia. It might; it might not. People with dementia might just be less likely to get glasses.

I think people get away with that kind of thinking more easily when the intervention being proposed seems generally unobjectionable anyway.

"Correcting vision problems for older adults" sounds like a good idea in its own right, so when someone adds a "and maybe it'll reduce dementia!" thought to the equation, even though the relationship might very well not be causal, people kind of shrug out a, "Sure, that'd be nice," in reply.

> It also builds on previous work about cataract surgery that showed lower rates of dementia over time in adults who had had their distance vision restored by having surgery.

This study does not (by what I read) directly address your question, since it doesn't say anything about whether the participants in this study had cataract surgery, LASIK, or anything else, or whether they even factored that in. But, evidently some other studies have been done on this.

The study is looking at best corrected vision. That is, the best vision achievable with refractive (glasses, contacts, lasik) correction.

Dementia is also highly correlated with hearing loss. It's intuitive to me that the mind could deteriorate when it loses touch with the outside world. It seems possible that dementia is much less a material deterioration in the brain than a condition that takes place when the brain loses its normal sensory stimuli.

We have seen people bounce back from early signs of dementia after cataract surgery.

I'd bet older people who have trouble seeing are more likely to be depressed and depressed people score higher (more likely to be) on dementia tests.

I've seen tons of things like family and active social lives helping with the disease but I bet it's just negative emotion and depressive symptoms make it worse rather than those things make it better.

There has to be more to this, since blind and deaf people exist and function in society. There may be direct correlations here, but there are definitely more factors involved.

I wonder if it has to do with the timing of the loss, and whether the loss happens at the same time as other losses.

For instance, if you have an accident and become blind as a teenager, but are otherwise fine, 1) you still have a fair degree of neuroplasticity, but 2) things in your life are generally getting better, which can encourage you to think your current situation will improve too (i.e., you'll cope better, even if you never see again).

If you become blind in your later years while everything else is declining, it makes sense that your prospects for improvement would be much lower.

The implied correlation and statistics here feels suspicious. Can they also say “we have seen people bounce back from early signs of dementia after getting eyeglasses” ?

Yes, this was my dad. He went from very healthy, active and social to suddenly aloof and reserved. People from his generation in India have a thing against regular medical checkups and only visit doctors when something is wrong. The visual degradation from his cataract was so gradual and severe but he failed to notice that. After I dragging him to a GP, he got his diagnosis in 5 minutes. He had a cataract surgery the same week and he was like 10 years younger instantaneously.

Anosmia (loss of sense of smell) is also linked to dementia. [0]

I wonder if it's a coincidence that declining vision, hearing, and smell are all linked to dementia, while the optic, vestibulocochlear, and olfactory nerves make up 3 of the 12 cranial nerves, [1] meaning they emerge directly from the brain.

---

[0]: https://www.nia.nih.gov/news/loss-smell-linked-alzheimers-co...

[1]: https://en.wikipedia.org/wiki/Cranial_nerves

Anosmia was one of the symptoms of Covid too, as I read at the time of peak Covid.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7488171/

Zinc deficiency is also associated with anosmia, and is also associated with dementia and Alzheimer’s.

Zinc will also lower insulin via the IDE enzyme.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883601/#:~:tex....

https://alzres.biomedcentral.com/articles/10.1186/s13195-021....

Saw comment late, but thanks. Will check those.

It is, and it is terrible. Whatever you eat is bland and you cannot smell anything.

Wow.

Fuzzier stimuli, fuzzier adapted reality...

Yikes.

Makes one wonder what one has unconsciously assimilated to.

My grandma was nearly completely blind due to macular degeneration from her early 70s, but she was sharp as a tack until she lost her hearing in her late 90s (this was also aggravated by covid-related isolation).

It would be interesting to see studies that compared the affects of different sensory losses, especially including when the loss occurred.

I've never heard anything about this, but are dementia rates higher among those who are congenitally without one of their senses?

from https://www.nextavenue.org/determining-the-best-care-for-her...:

"Hope Lanter, lead audiologist for Hear.com, says that because people with congenital deafness don't have access to sound, "the dementia risk is not strongly correlated due to the brain not encountering a change in stimulation that occurs with late deafened adults."

However, congenitally deaf people do wear hearing aids and have access to some, or many, sounds. But there is apparently little to no research that has assessed the dementia risk for this marginalized group.

"There are no studies that I know of that confirm a higher risk of dementia for Deaf individuals," said Melissa Karp, a doctor of audiology with the Audiology & Hearing Services of Charlotte, located in Charlotte, North Carolina. "Members of the Deaf community have their own language with structure, syntax and interactions with others. You would also have to tease out other factors like genetics and socioeconomic status before making that determination.""

I think this makes sense. If your brain has been relying on your sense of hearing for certain information your whole life, any new damage to that ability will leave your brain without that information. If you've never been able to hear, your brain has no dependence on sound for information.

I wonder if the cognitive dropoff for Deaf people who get cataracts is more or less severe than for hearing people who get them, since presumably they're even more reliant on their sight for information than hearing people are.

Sadly this bodes ill for the people suffering hearing loss from COVID vaccines. And STILL you have lowlives trying to bury this information (there's one in this thread). Why?

Try living with a 9 kHz tone in your ear 24/7. Tell National Geographic, NBC, hearing experts, vaccine researchers, and thousands of victims that it's "made up."

Hurry and "flag" this. Bury the information as fast as you can, so more people get hurt.

https://www.nationalgeographic.com/magazine/article/covid-va...

https://www.abc15.com/news/local-news/investigations/can-the...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8443418/

https://www.news-medical.net/news/20220523/Pfizer-COVID-19-v...

https://www.nbcnews.com/health/health-news/tinnitus-rare-sid...

Facebook group for victims, with several thousand members: https://www.facebook.com/groups/265035901879921/

Don't try to pretend this is "anti-vax," because if the afflicted people hadn't gotten the vaccine, they wouldn't have discovered this side effect. In my case, it was a nearly useless second booster, which I never would have gotten if I had access to the information to weigh the risks and benefits. THAT is the huge crime in covering this up, and yes, it has been covered up. People could have opted to use N95 masks more diligently, for example, and skipped mostly-ineffectual boosters.

This is HN, mate. You have to forget about common sense and having a serious discussion here.

from https://rnid.org.uk/hearing-research/hearing-loss-and-dement...:

"There is strong evidence to show that:

- hearing is an essential part of brain health - mild hearing loss doubles the risk of developing dementia - moderate hearing loss leads to three times the risk - severe hearing loss increases the risk five times."

also, from https://publichealth.jhu.edu/2021/hearing-loss-and-the-demen...:

"Hearing loss is estimated to account for 8% of dementia cases. This means that hearing loss may be responsible for 800,000 of the nearly 10 million new cases of dementia diagnosed each year."

No doubt.

I have noticed as my vision has gotten worse that sometimes I just don't pay attention to what is in front of me. At times it takes a lot of effort to parse out the blurry image so I just let it all meld. In TV shows and movies where I used to study the background sometimes just turn into basically radio plays where I just get the gist of where the characters are, but don't have the energy to pay attention to details.

This has also affected my reading. I am much more likely to search for a Youtube video or other audio explanation of a subject than read it myself - since again reading for long periods takes a lot more concentration when the text is blurry/shifting around.

There is no way to wont lead to mental degradation over time.

If you don't mind my asking -- how old are you?

mid 30s

Have you looked into correction vision, e.g., glasses or lens?

I wear a pair and have minimal problems when wearing them. When they're off I would likely experience similar to yourself.

I do wear glasses and they do help, but it is not enough. I just got new glasses couple months back. Everything is fine when I wake up, but as the day progresses (I guess) my eyes more tired and everything gets blurrier and blurrier.

Have you tried watching movies with audiodescription?

No and it is not so bad (at least I don't think it is) that I can't see what is happening. It is like everything has this slightly shifting blurring on it, basically details go.

One issue with modern life is that we spend an awful lot of time focusing at fixed distances, bright screen in dark room etc.

I learned two exercises in Yoga for getting the eyes muscles into shape.

The first is basically focusing at different distances: tip of the nose, outstretched thumb, window in front of you, and a tree outside for example; then repeat the sequence back and forth.

And the second tracing/exploring the border of your visual field using the thumb by moving it as far left/right/up/down as possible without losing sight of it while keeping the head still.

After hearing Andrew Huberman talk about the relationship between vision and our dopamine system, I would not be surprised if we start finding more correlations of mental health with vision.

But there's also the recent findings inversely correlating myopia with amount of time spent outdoors (and even some reduction in myopia for people who start spending more time outdoors). So vision could just be a proxy for sedentism?

Or is poor vision, hearing, smell a sign of poor brain health?

Certainly not exclusively. We have a pretty thorough understanding of vision loss with age, and almost all of it is caused in the optics part of the system (that's why you can compensate with glasses or eye surgery for such a long time), not in the optic nerve or after it.

Hearing is pretty similar, no idea about smelling.

I'm pretty sure you could say this other ways, like

"dementia more common in older adults with erectile dysfunction"

Problems with poor circulation or arteriosclerosis correlate with dementia and also correlate with erectile dysfunction.

And then there was the study that said folks who take medicine for erectile dysfunction stave off dementia: https://www.nih.gov/news-events/nih-research-matters/viagra-...

But that's not saying the same thing differently. It's saying something separate - and not examined in this study - that looks like it could plausibly generalize together with this one.

While the direction of causality is (usually) hard to determine based on observational data, given that we observe a similar effect in individuals with hearing impairments and, AFAIR, in people with limited mobility, it seems that decreased sensory stimulation plays a role in the development of some dementias. There is also a recent pilot study about a positive effect of olfactory stimulation [1].

https://www.frontiersin.org/articles/10.3389/fnins.2023.1200...

When it comes to the brain, I don't think causation (vs. correlation) matters that much. The brain is an association machine.

To clarify my earlier comment, if your goal is to prevent or delay dementia, then you would want to know whether dementia causes poor vision or poor vision causes dementia (via reduced visual stimulation or reduced engagement in cognitively engaging activities that require good vision like reading, some sports, etc.). This is because there may be effective interventions and strategies for dealing with vision impairments.

Yes. What I meant is that in the absence of such perfect knowledge (whether dementia causes poor vision or poor vision causes dementia), which is usually the case[1], we can pursue these strategies anyway because the nervous system learns by association and by introducing a perturbation to its inputs, it could adapt toward our goal.

[1] Because the brain and body is a huge complex system and it's hard to untangle cause and consequence: There is usually no single cause and a lot of feedback cycles where the consequence could reinforce its cause.

Sadly probably the biggest short term impact it’ll have is in entering insurance models.

Did they control for blood sugar or diabetes incidence? (I’ll check)

The link between diabetes and retinopathy is conclusive. Between diabetes and dementia or Alzheimer’s, prospective.

At first glance, yes, and that reduces the hazard ratio, but a substantial gap remains.

Undiagnosed cataract is a big thing in developing countries. Vision loss from cataract is gradual so many older people don't realize they're turning blind.

Selenium may be the common denominator. It helps recycle glutathione via the GPX enzymes. So it stimulates antioxidant defense.

https://www.frontiersin.org/articles/10.3389/fnut.2023.10428...

https://www.sciencetimes.com/articles/34038/20211019/around-...

> Dementia was defined as scoring 1.5 SDs or more below the mean in 1 or more cognitive domains, an AD8 Dementia Screening Interview Score indicating probable dementia, or diagnosed dementia.

As expected they did not diagnose clinical dementia so the findings are highly debatable.

More people need to look at actual metrics used instead of the clickbaity headlines.

Also if you want to imply any kind of causation the study needs to be much longer. Here they started the study after people were in their 70s which is fairly late already and you are much more likely to have bias or random people having cognition decline no matter what.

Neat to see. It seems to align with expectations, in that many vision troubles are not with the eyes.

That said, I am surprised that the vision troubles you will have from cataracts is the same. I was originally skeptical of the opening claim that many vision issues are preventable, but seeing that surgical corrections has a positive impact does show this.

"in that many vision troubles are not with the eyes."

I think it's the same with hearing. I have massive troubles understanding people in loud environments but on tests my hearing was above average. Seems my brain (in this case I think my autistic traits) just doesn't process the input very well.

That would be my expectation. Would be neat to see a comparative study with hearing interventions and how they impact dementia. Would put even more importance on quality hearing aides.

I have the same ailment. I did find that wearing ear plugs to concerts helps me filter out the noise and better hear and understand people around me talking.

Yes, well-known. Likely an “ear teaming” issue. Good binaural hearing is very important to filtering speech.

My reading vision has gotten worse over the last 5 or so years as I've gotten older - and when I'm trying to look at something closely, like I used to be able to do, I do feel for a moment like it's not my vision but my brainpower reducing. There is definite confusion.

Not addressed in this article, but the findings sort of imply to my naive and speculating mind that being blind might lead to increased risk of dementia. Congenitally or otherwise. I had not heard that, and I feel like it might have become folk wisdom by now if it were true.

Maybe the widespread ANTI-VEGF treatments that people are getting for wet AMD are a contributing factor. VEGF is a known protective mechanism against dementia, and the common ANTI-VEGF medications have been shown to enter the brain.

Had trouble understanding this. To save others some searching:

AMD = age-related macular degeneration https://en.wikipedia.org/wiki/Macular_degeneration

Anti-VEGF = Anti-(vascular endothelial growth factor) therapy https://en.wikipedia.org/wiki/Anti-VEGF

Isn't there another study that says that adults with hearing issues have a higher chance at dementia.

And yet another with adults who spend more time isolated?

Almost as if the issue might be isolation due to a diminishing amount of sensory input from external sources.

https://eyewiki.org/Visual_Variant_of_Alzheimer%E2%80%99s_Di...

I find that very questionable.

Name 70+ year olds who have perfect eyesight. How many do you know?

My unprofessional opinion is that these are both explained by a third variable, excessive consumption of carbohydrates, starches especially. (It also explains the correlation between poor dental health and dementia).

Myopia is known to be promoted by excessive carbohydrate consumption.

Do you have any evidence to support any of these claims

I will interject that high insulin levels are linked to dementia and Alzheimer’s and so is diabetes.

But it might be more than just the carbohydrates and also name Balance of omega-3 and omega six.

https://alzheimer.ca/en/about-dementia/how-can-i-prevent-dem....

I am personally skeptical of the role of omega-3 and omega-6 in dementia, at least, one should never take these as supplements. It is a medical fact that they are highly unstable and basically worthless after only a day or so on the shelf, if not harmful.

One should only look to studies of genetically identical populations (you should be able to find one about nigerians in america) that acquire dementia at a high rate to observe that something about our capitalistically engineered environments is principally to blame.

raypeat.com

It's all a google away.

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