First of all, for any unfamiliar with the lymphatic system, it’s mostly the body’s clean-up system (as well as a big part of the body’s anticancer system).

See: The Lymphatic System Against Cancer & More

It may not be the most glamorous job, but it’s certainly an essential one.

There’s no lymph in the brain, but…

Because of the blood-brain barrier (BBB) that keeps the astonishingly sensitive brain as safe as it can from unwanted things, there are many aspects of our physiology that only happen inside the brain, or only happen outside of it, as the compounds in question may be too large to get through the BBB.

The lymphatic system is, in and of itself, an entirely outside-of-the-brain affair. So, how does stuff get cleaned out from the brain (such as beta-amyloid and alpha-synuclein clearance, to avoid Alzheimer’s and Parkinson’s, respectively)?

The glymphatic system (a portmanteau of glial cells doing the job of the lymphatic system) is the brain’s own cleanup crew, and we wrote about it here:

How To Clean Your Brain (Glymphatic Health Primer)

Why lymph still matters for the brain

Although the glymphatic system is doing a (hopefully) fine job of scrubbing up the brain, if the lymphatic system isn’t working at least as well, then this becomes the equivalent of what would happen if you at home were very attentive to taking the trash out, but the garbage disposal crews stopped doing their job, or did it much less well than they need to. Soon, you’d end up with a mountain of trash at home, even though you were doing your part correctly.

In short: the glymphatic system needs to pass the waste on somewhere, and the lymphatic system is its go-to.

You may be wondering about the role of blood in all of this, and the answer is that no part of any of the above systems can do its job without adequate oxygenation, and our blood also assists in the transport of things removed—which is one of the reasons why there are blood-based Alzheimer’s tests that can be done; they measure certain markers of neurodegeneration that become present in the blood having left the brain:

Early Dementia Screening From Your Blood & More ← the “and more” is actually quite interesting, but it’s the blood we’re interested in for this section

What can be done about it

Our first two links up above, about the lymphatic and glymphatic systems, respectively, also tell how to look after each of them, but we’ll mention a few salient pointers here.

For the lymphatic system:

• do lymphatic massage
• exercise, with a focus on maximizing movement
• eat an anti-inflammatory diet

For the glymphatic system:

• do vagal massage (Vagal! Not vaginal, which will not help! Or rather: it won’t help the glymphatic system, anyway)
• exercise, and/but also rest well (good quality sleep)
• eat omega-3 fatty acids

For more details and suggestions on each though, do check out:

Lymphatic health primer | Glymphatic health primer

How this was discovered

Until as recently as 2014, it was not known that there was any part of the lymphatic system around the brain, waiting to take things from the glymphatic system. Since then, research has slowly been done about the relationship between the two, how things work, and what affects what and how.

Most recently (the study was published two days ago, at time of writing this) it was discovered that, in mice at least, improving lymphatic function just outside of the brain (the meningeal lymphatic vessels, responsible for draining waste from the brain) improves memory.

Aged mice who underwent a process that rejuvenated the meningeal lymphatic vessels, performed better in memory tests afterwards.

How this worked, step-by-step:

• The mice were given a special protein that rejuvenated the meningeal lymphatic vessels¹
• The lymphatic vessels were then able to do their job better
• This meant that the glial cells of the glymphatic system were no longer drowning in excess stuff
• This reduced levels of a protein that says “help, too much stuff!” and starts inhibiting everything it can to try to cope²
• This meant that neural activity was no longer being suppressed, and memory improved

Technical bits for those who want it:

¹ We’re not being secretive about what this special protein was; it’s just that the special protein is called adeno-associated virus 1 cytomegalovirus murine vascular endothelial growth factor C, or “AAV1-CMV-mVEGF-C” for short, so for readability, “a special protein” does the job. Suffice it to say, a) you can’t exactly buy AAV1-CMV-mVEGF-C on Amazon, and b) you wouldn’t want it anyway, you’d want its close cousin AAV1-CMV-hVEGF-C (“m” for murine, i.e. mousey, vs “h” for human)

² This one’s just called interleukin-6 (IL-6); perhaps you’ve heard of interleukin; we’ve mentioned it sometimes before.

You can read the paper in its entirety here; if you don’t mind reading very technical stuff, it is very interesting:

Meningeal lymphatics-microglia axis regulates synaptic physiology

Enjoy!