This brain fog research by researchers Michelle Monje and Akiko Iwasaki sounds interesting. So excerpts:
It seems that in brain fog, specialized microglia in the white matter
may have become permanently switched on:
“There’s a unique subpopulation of microglia in the white matter called axon tract microglia,” Monje says. These have a specific genetic signature, she continues, and “are exquisitely sensitive to a wide range of insults,” like inflammatory or toxic stimuli.
In response to these stimuli, microglia can become perpetually reactive. One consequence is that they can begin eating away at needed neurons or other brain cells, which further disrupts the brain’s homeostasis. In the case of Covid-19, the scientists found that this reactivity persisted even at seven weeks after infection.
The factor that is switching on these microglia appears to be CCL11
To figure out what exactly caused the microglia to become reactive, the researchers looked for the cytokines that had reached elevated levels. Specifically, Anthony Fernandez Castaneda, a postdoctoral researcher in Monje’s laboratory and a study coauthor, found CCL11—a factor that can decrease the generation of new neurons and impair learning or memory. “The elevated CCL11 result was very interesting, because it could potentially explain why some Covid survivors experience cognitive symptoms,” he says.
Interestingly, CCL11 was found elevated in the brains of ME/CFS too, in this study
Another area these researchers looked at was the effect of COVID on the brain's oligodendrocytes
; these are cells which create the myelin insulation on neurons, which facilitates neuron to neuron communication:
[COVID] infected mice had lost approximately one-third of their mature oligodendrocytes, and had a statistically significant drop in myelination compared to mice in a control group.
In terms of therapeutic interventions, if we can find substances which reduce CCL11 secretion, then that may help treat brain fog.
I found this paper
which says blackcurrant anthocyanins
suppress CCL11 secretion. For those in the UK, perhaps drinking lots of the blackcurrant drink Ribena might be beneficial.
Specifically, the paper found the blackcurrant anthocyanins delphinidins
were involved in CCL11 suppression.
There is a supplement called Delphinol
which contains delphinidins; and there is a supplement called Biotest Indigo 3G
which contains cyanidins.