The usually-listed 7 known risk factors of dementia (in general, not just Alzheimer’s) do not include today’s item. For a recap, those were:

The 7 Known Risk Factors For Dementia

The bonus risk factor

This idea is not completely novel; it’s been known for a while that traumatic brain injury (TBI) can increase the risk of dementia, but it has generally been chalked up to “if you damage an organ, then that organ does not function so well afterwards”.

However, in the case of Alzheimer’s, it seems there’s something deeper at play. Specifically, a study that found…

❝…traumatic brain injury alters the small vessels in the brain, resulting in an accumulation of amyloid beta—a hallmark of Alzheimer’s disease.

The findings suggest that vascular dysfunction could be an early driver in neurodegenerative disorders rather than being caused by neuronal damage.❞

This association held true even in quite young patients!

The study from Sweden looked at brain tissue from TBI patients (who had had to have brain tissue removed for medical reasons due to bleeding and swelling), and found that the (traumatic) changes to the vascular smooth muscle cells were associated with increased aggregation of amyloid-β.

In terms of establishing cause and effect: since it could be safely concluded the amyloid-β had not caused the TBI (which all had external explanations such as “car crash” or such), it can be deduced that almost* certainly the TBI caused the amyloid-β aggregation.

*because little to nothing in science is every truly certain. As in life in general, really; the difference is that scientists admit it!

You may be wondering: what was the control? It would be a very generous group of citizens indeed who would volunteer bits of their brains that hadn’t needed removing. However, the answer is that the control brain bits came from a biobank, and were from uninjured patients with no history of TBI or neurodegenerative disorders, and who had died from systemic, unrelated causes. Having been dead for a matter of hours, and the fixation time for the brain bits from the living people taking long enough that everybody’s brain bits had been out of their respective living bodies for a similar length of time, this was deemed an acceptable, if imperfect, control.

You can read the study in its entirety here; it is fascinating:

Traumatic brain injury causes early aggregation of beta-amyloid peptides and NOTCH3 reduction in vascular smooth muscle cells of leptomeningeal arteries

The practical take-away

The practical take-away, of course, is: look after your brain

Not just in the sense of eat fiber, get healthy fats, move more, get good sleep, stay intellectually stimulated, etc*, but also in the sense of “keep your brain physically safe”.

Now, you may think that you already try not to get into car crashes, and perhaps you do not compete in contact sports, but do be aware that one of the leading causes of TBI in older people is, ignominiously, falling down.

And if you think “that only happens to older/other people”, then be aware: there’s a first time for everything and you are not immune. With that in mind, do check out:

Fall Special! ← the seasonal title notwithstanding, this is about not falling down in the first place, and being less injurable if you do fall down

*This was a modest and vague list for brevity’s sake, so for much more detail, enjoy:

How To Reduce Your Alzheimer’s Risk ← this is rather more comprehensive

Want to know more?

Here you can read about the largest study of its kind into lifestyle factors and Alzheimer’s disease:

Alzheimer’s Causative Factors To Avoid ← the methods and conclusions of Dr. David Snowdon’s famous “Nun Study”

Take care!