Also, inflammatory molecules to the side, some of those senescent cells are likely astrocytes (a kind of glial cell).

They're key to the CNS' use of glucose - they convert glucose to glycogen, which the nerve cells use.

Nerve cells can use either glycogen or ketone bodies for energy, and, possibly interestingly, patients suffering dementia show cognitive improvement when they're either on a ketogenic diet or otherwise have ketones in their bloodstream (the studies I've read mention ketone esters, which are directly absorbed in the small intestine. Gotta wonder if medium chain triglycerides which also supply ketones directly - and are an order of magnitude cheaper - would do the same).

Without functional astrocytes (and glucose) or ketone bodies, nerve cells die.

There's also some interesting work on ketones/ketosis and CNS resilience to O2 starvation, O2 poisoning, and TBI. No idea if this latter is at all connected, but it is suggestive.