Back in 2015, when I build my pre-pack, it was based on the hypothesis that my emotional symptoms were caused by the disruption of the kynurenine pathway toward the production of pro-inflammatory cytokines in the brain, like quinolinic acid ( see one of my pots about this at
https://poiscenter.com/forums/index.php?topic=1988.msg15559#msg15559 ). I have no cognitive symptoms, but as quinolinic acid seems to me to be responsible for emotional symptoms, other toxic metabolites like 3-hydroxykynurenine or 3-hydroxyanthranilic acid can be responsible for these cognitive symptoms.
I recently stumbled upon this 2019 review article showing that this hypothesis is still the object of many scientific studies:
https://sci-hub.se/https://pubmed.ncbi.nlm.nih.gov/30844963/ .
Also, another very recent article, from June 2021, gives a detailed description of the kynurenine pathways, and how it can end in producing toxic metabolites, and how they disrupt the normal functions of the brain. This article also mentions the molecules that in development that target the enzymes of the kynurenine pathway, in order to control problems like depression, memory loss, and the like:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306609/