[1] "Brain Damage in Commercial Breath-Hold Divers" https://journals.plos.org/plosone/article?id=10.1371/journal...
[2] "Do elite breath-hold divers suffer from mild short-term memory impairments?" https://cdnsciencepub.com/doi/10.1139/apnm-2017-0245
Ref. [2] is especially concerning to me in pushing in any sort of static apnea training or breathwork: "The time to complete the interference card test was positively correlated with maximal static apnea duration (r = 0.73, p < 0.05) and the number of years of breath-hold diving training (r = 0.79, p < 0.001)."