Can A High School Test Predict Alzheimer's?
Getting dementia and Alzheimer’s is a terrifying prospect. It can also be bankrupting if you require lengthy home or institutional care.
So when the Washington Post published a story about a test predicting our risk of Alzheimer’s as far back as adolescence, I was intrigued. A half a million kids took the test, so now we have definitive data on whether we’ll get Alzheimer’s? Let’s have a look at that test!
Well, they give some sample questions in the Washington Post article, but nobody really wants to sit through a two day test that somebody cooked up in the 1960’s when Dick and Jane books were seriously how we learned to read. Or we would, if it would really predict our chances of getting a dread disease.
What the researchers found after tracking down the test participants using their fifty-year high school reunions was that lower scores in mechanical performance predicted about 17% more risk of dementia for men, while lower scores in verbal memory predicted about 16% of the risk for women. Remember, these kids were tested for two days, covering almost twenty different subjects. So my first impression was that they gathered lots of data, found a couple of significant numbers, and published those. The summary makes it look like cherry picking for publication.
But looking at the full JAMA study, it wasn’t just those two areas that showed a connection. The same results held about at about 12% for almost all the different tests. So doing poorly on this test did increase the subjects’ risks of getting dementia. By about 12%, which isn’t that much, but also isn’t nothing.
It’s worth noting that we’re not talking about a half a million kids anymore. A quarter of them have died, which is pretty noteworthy in itself and I’d like more follow up on if getting tested so much in the 1960’s killed them off quicker. Out of the 377,000 initial kids, researchers only found 143,00. Of those, the follow up study was done on fewer than a 100,000. The information used was based on medicare results, which may only track the worst cases of Alzheimer’s and miss between 5 and 35% of the cases. So we’re ultimately talking about a 12% increased risk that may not really be there.
But let’s say it is there, that 12% increased risk for poor performing children on this test for later dementia and Alzheimer’s. It’s tempting to make the claim that financially poor children tend to do poorer in school and also receive less healthcare. So as they age, that decreased income could result in poorer long term health. In other words, the test tells us nothing we don’t already know, that being poor in America is bad for your health.
Yet when other researchers have tried to make that claim, it shows that income and Alzheimer’s do not have a straight connection. It’s much more cyclic, with Alzheimer’s deaths varying with wealth over time. Being rich doesn’t seem to protect against Alzheimer’s.
If not wealth, the second simple answer is the old standby, use it or lose it. The children who do poorly on the tests use their brains less throughout their lives. So of course they are more likely to develop dementia. They didn’t have as far to go. A Scottish study makes this claim, “Compared to the highest intelligence group (≥115), dementia risk was raised in the lowest-scoring category”
But is this because the children didn’t have as much to lose? Another British study found that intelligence pretty much factors into everything health-related. “Childhood intelligence was inversely associated with all major causes of death.” In a major international study, the “advantage in cognitive test scores was associated with a 24%...lower risk of death.” And yes, they thought of mumsy and dadsy’s wealth being a factor, and it might make up about half the lower risk, but not all of it. If we look at the 12% difference overall in the U.S. study, it might well be because the children with greater intelligence knew how to take better care of themselves.
But people tracked in other countries don’t necessarily do better with dementia based on intelligence. In one study of 90-year-olds the risk was increased by more physical activity and genetic susceptibility (APOE ɛ4) and cut in half by having hypertension. An assessment of sixty different studies found that low intelligence was just one of many factors: “approximately a third of Alzheimer’s dementia cases could be attributed to seven potentially modifiable risk factors: diabetes, midlife hypertension and obesity, smoking, depression, cognitive inactivity, and low educational attainment” Those researchers found more likely culprits in a host of environmental factors: “air quality, toxic heavy metals, other metals, other trace elements, occupational-related exposures, and miscellaneous environmental factors.” Of those, smoking and being exposed to heavy metals feature as bad ways to keep your memory in old age.
Let’s add to those risks the ongoing discussion about viruses and Alzheimer’s, which just came down on the side of viruses being a factor recently. If those researchers are correct, then have a low-grade viral infection is a major risk for developing memory loss.
So, does the test tell us who will get Alzheimer’s? No. It tells us what we already know, that people with greater test intelligence are either A) smarter or B) more likely to follow the rules set down for them by authorities like doctors. In either case, doing better on tests lowers your risk of dying about 12% for all diseases and causes over people who don’t do as well. The Alzheimer’s connection is just rediscovering that same factor in another way.
The bigger issue is how we can best prevent Alzheimer’s and dementia. Is it taking more tests until we’re better at them? Is it taking antivirals to prevent low grade infection? I’ll be working on a book tentatively entitled The Dementia Diet: How Not To Lose Your Mind. It’s an exploration, but I’d like to go beyond the “eat your veggies” basic advice we’re getting now. Clearly, it’s not enough. Let me know if you have questions you’d like answered, because that’s the purpose of my books.
Update: As I'm doing preliminary research, two things that I want to tell current caregivers. One, check those meds! Particularly if mom/dad has been on the same or increasing blood pressure meds.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4888427/ Some studies found half of older nursing home residents were taking inappropriate medications.
A 22.4% higher prevalence of dementia in subjects with OH (orthostatic hypotension) was obtained https://www.ncbi.nlm.nih.gov/pubmed/30247788