Glowing Mouse Heads and How Our Brains Get Washed

Herewith, edited excerpts from a Washington Post article of special interest to people with brains:

The lymph network carries immune cells throughout the body and removes waste and toxins. It was accepted wisdom for more than 300 years that the network didn’t extend into the brain. 

Three years ago, scientists trying to develop a more precise map of the lymphatic system used genetically-modified mice whose lymphatic vessels glowed when illuminated by a particular wavelength of light. The mice had been given a gene from a species of glowing jellyfish.

Seeing that the mouse’s heads glowed, the researchers realized that the lymphatic vessels extended into the brain after all. This was surprising, to say the least: In the 21st century, major findings involving basic human anatomy are rare. “These days, you don’t make discoveries like this”, one of the scientists said.

Since the lymph network also extends into human brains, this discovery has major implications for a wide variety of brain diseases, including Alzheimer’s, multiple sclerosis, stroke and traumatic brain injury.

Researchers have identified two networks: the vessels that lead into and surround the brain, and those within the brain itself. The latter is called the “glymphatic” system for the glia, the kind of neuron that makes up the lymphatic vessels in the brain. The glymphatic vessels carry cerebrospinal fluid and immune cells into the brain and remove cellular trash from it.

There is evidence that when the systems malfunction, the brain can become clogged with toxins and suffused with inflammatory immune cells. Over decades, this process may play a key role in Alzheimer’s disease, Huntington’s disease, Parkinson’s disease and other degenerative illnesses. 

“This is a revolutionary finding,” one researcher says. “This system plays a huge role in the health of the brain.” She describes the glymphatic system as like a dishwasher for the brain. “The brain is very active and so it produces a lot of junk that needs to be cleaned out.”

In hindsight, the system should have been noticed long ago. When the skull and head are dissected, the vessels are visible to the naked eye. But no one bothered to really look.

The vessels have also been implicated in autoimmune disease, such as multiple sclerosis. Researchers knew that the immune system has limited access to the brain. But at the same time, the immune system kept tabs on the brain’s status; no one knew exactly how. Some researchers theorize that the glymphatic system could be the conduit. In diseases like multiple sclerosis — where the body’s immune system attacks certain brain cells — the communication may go awry.

Recently, Harvard University researchers reported that glymphatic flow is significantly decreased in the period just before a migraine. The intense pain in these headaches is caused largely by inflamed nerves in the tissue that surrounds the brain. The authors of the study theorize that faulty clearance of molecular waste from the brain could trigger inflammation in these pain fibers.

One key to glymphatic performance seems to be sleep. At least in mice, the system processes twice as much fluid during sleep as it does during wakefulness. It’s possible that sleep dysfunction may contribute to Alzheimer’s and perhaps other brain illnesses: “You only clean your brain when you’re sleeping. This is probably an important reason that we sleep. You need time off from consciousness to do the housekeeping”.

It also appears that sleep position is crucial. In an upright position — someone who is sitting or standing — waste is removed much less efficiently. Sleeping on your stomach is also not very effective; sleeping on your back is somewhat better, while lying on your side appears to produce the best results. The reason for these differences might be related to the mechanical engineering of the lymphatic vessels and valves; the healthiest approach may be to move periodically while you sleep.

Sleep is probably not the only way to improve glymphatic flow. Omega-3 fatty acids and deep breathing may also improve glymphatic functioning. 

Not being a scientist, I can’t evaluate these studies, but it makes sense that brains produce a lot of junk that needs to be cleaned out. (And you didn’t think the President would come up in this post.)

Happiness, Especially For the Demented

Not being a Dutch citizen, I’m not sure how much it will cost to live in this great-sounding village, but I’m moving in as soon as possible. I bet they encourage blogging for all the residents.

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If you want to join me at this “dementia-focused living center called De Hogeweyk, aka Dementia-Village”, you can read about it here.

It’s a very serious subject, of course. How to keep millions suffering from dementia safe and even reasonably happy, if possible. Although that raises the question: should we invest any resources in making the demented happier? 

Mari Ruti, a professor at the University of Toronto, argues that happiness is overrated. Or rather, the kind of well-balanced, anxiety-free happiness demanded by one’s corporate co-workers (“Smile!”) is overrated. The pursuit of that kind of happiness:

(1) Stifles the “idiosyncratic and potentially rebellious energies that, every so often,” break through our bland social personas;
(2) Encourages emotional numbness;
(3) Serves the cultural, economic and political status quo;
(4) May be contrary to human nature (evolution didn’t design us to be happy); and
(5) May lead to lives that are ultimately less satisfying or productive than more anxious lives would be.

Professor Ruti’s conclusion:

There is something quite hollow about the ideal of a happy, balanced life—a life unruffled by anxiety. It’s why I think that underneath our quest for vibrant health lurks a tragic kind of discreet death: the demise of everything that is eccentric and messy about human life. Our society sells us the quick fix: If you get a cold, take some decongestants; if you get depressed, take some antidepressants; and if you get anxious, take those tranquilizers. But what are we supposed to take when we lose our character?

Clearly, if we define “happiness” as “a well-balanced state marked by a lack of anxiety and the presentation of a pleasant persona”, it sounds like a questionable goal, especially for the budding Beethovens and Van Goghs among us (although it sounds pretty good for those of us with dementia). I wouldn’t dismiss Professor Ruti’s critique, however, even if she seems to exaggerate the benefits of living on the edge. There are, after all, more important things in life than happiness. For example, the elimination of real suffering, both physical and psychological:

I do not doubt that it would be easier for fate to take away your suffering than it would for me. But you will see for yourself that much has been gained if we succeed in turning your hysterical misery into common unhappiness (Sigmund Freud and Josef Breuer, Studies on Hysteria, 1895).