Astounding. Breakthrough. Game-changing.
Usually when we hear words like these applied to something in medicine, the reality turns out to be much more mundane. These types of words are usually pulled out in an effort to generate enthusiasm for the latest drug. They're tossed around to promote the newest, priciest medical procedures. They’re most often marketing hype at best.
Last year, however, scientists at the University of Virginia and the University of Rochester Medical Center made two separate discoveries that truly were astounding. They really were game-changing. They’re radical enough that the textbooks will literally have to be re-written to accommodate them. And they’re both firmly located in your brain.
What they’ve discovered forces us to change the way we look at the relationship between the immune system and the brain. And it gives us new insight into how the brain handles waste-disposal. Together, these two discoveries may give us the clues we need to finally understand just what happens in many neurological diseases. Not just Alzheimer’s but Parkinson’s, MS, and more.
How on earth did we miss this?
It’s no surprise when we discover new things on a microscopic level. Microscopes have been around for about 400 years, but it was only during the 20th century that they became really powerful. The same applies to many physiological processes. Sophisticated imaging technology has only existed for a few decades, and we’re constantly learning new things. Only recently have we been able to study the living body with things like MRI and CT scans.
Gross anatomy, however, is another story. Gross anatomy is the study of the structure of organs and tissues. The shape and structure of muscles and bones belong to gross anatomy. The path and workings of the circulatory system, the internal structure of your eye — this is all gross anatomy. We’ve been dissecting and studying the body in fits and starts since the time of the ancient Greeks.
You’d think that with this much study, we’d have mapped everything we can see with the naked eye. And for a long, long time, this is exactly what we thought. We were pretty smug about it. Gross anatomy had nothing left to discover, we thought. We’d mapped the body thoroughly. We might not know what everything does, but we know what it looks like and where it’s located.
We were wrong.
Last year scientists discovered a whole new set of vessels in the brain. The brain, it turns out, has lymph vessels just like the rest of the body. And it’s taken us hundreds of years to notice it.
Is this why Alzheimer’s and inflammation go hand in hand?
You’re already familiar with the circulatory system — the veins and arteries which network through your body, powered by your heart. What you may not know is that your body has a second network of vessels that’s almost as extensive and equally important. This is your lymphatic system, and it has several jobs.
It’s part of your immune system, and it shuttles immune cells to the site of infection. It drains excess fluid from the tissues of your body. And it helps clear away cellular waste. Unlike the circulatory system, it isn’t powered by a central pump. Instead, fluid is moved by a combination of gravity and muscular contraction.
The lymphatic vessels are connected to structures called lymph nodes. These act as a sort of filter to clear out harmful substances. They’re also home to immune cells which will attack foreign invaders such as bacteria. When you move, your muscles squeeze the vessels and push whatever fluid they contain toward the lymph nodes, where it’s processed and recirculated. If you’ve ever had a sore throat, you may have noticed a tender bump on the side of your neck or under your ear. If so, you’ve experienced your lymphatic system at work.
Every part of the body has lymph vessels and nodes. Every part, that is, except the brain...or so we thought. Until last year’s discovery, we thought that the brain was a closed system, cut off from the body’s immune system. The discovery that the brain does have a lymph system — that the body and brain share this system — totally changes the picture.
It shows us that there is a route for infection and inflammation to make it from the body to the brain. We haven’t had time to really process the implications yet, but it could explain why inflammation seems to play a role in neurodegenerative diseases like Alzheimer’s .
This discovery could explain why plaque builds up in the brain
The second discovery may be even more important.
The brain is unlike anything else in the body, and in many ways it really is a closed system. Like the rest of the body, it contains many blood vessels which carry nutrients and oxygen to it and carry waste products away. It also contains a specialized substance called cerebrospinal fluid. This fluid seeps through the brain and spinal cord, clearing out waste products — like the beta-amyloid plaques of Alzheimer’s disease.
Scientists also discovered that the brain has a whole other waste-disposal system that we never knew about. It’s gone undiscovered because it was hiding in plain sight — it sort of “piggybacks” along the blood vessels in the brain, running along and outside of them. This second waste disposal system circulates cerebrospinal fluid much more quickly. It’s much more efficient. And with the newly-discovered lymph system, it clears out waste faster than we ever imagined.
Where the other system is a trickle, this one is a faucet. And malfunctions in this system just might be part of the reason that Alzheimer’s hallmark plaques and protein tangles build up in the brain.
Both of these discoveries are like finding there’s another planet in our solar system that we never noticed. And although we haven’t had time to study them thoroughly and we certainly don’t understand them yet, the implications are huge. These two findings could be the missing link that ties together the things we do know about neurodegenerative diseases. With some serious science and a lot of luck, they might give us the key to treating what has heretofore been untreatable.
And above all, they underscore the fact that no matter how much we may think we know it all, the science is never “settled.” It’s continually evolving as we learn, and today’s facts often become tomorrow’s fallacies.
And sometimes, we have to rewrite the textbooks.