There is some more experimental validation for those who feel that adverse factors in their environment are affecting their brain function. This study on mice, https://www.sciencenews.org/article/mold-may-mean-bad-news-brain, found slowing of new cell growth in the hippocampus (memory center) in mice exposed regularly to the toxic mold Stachybotrys. The mice were observed to have increased anxiety and decreased memory function. I have witnessed these symptoms in people who have been exposed to environmental mold, and I believe that these experimental results can be extrapolated to humans.
The simple, but time-consuming, step of getting a good environmental exposure history is essential for those who suffer symptoms beyond the usual and do not seem to respond to conventional treatments.