I have had MBS patients complain of “brain fog” and memory disturbances which do get better and resolve over time with treatment. I, myself, recall realizing that I could no longer do math in my head when I was sick. I got back this skill after a few years of recovery/post-recovery and feel like my brain is working just fine now, but I do feel like it took a few years to feel that way and I found the more I challenged it (by returning to work and taking on more multi-tasking, the better it has gotten. I have also had patients who were clearly getting dementia, beginning to have memory disturbances, and I was not able to help them because they had high degrees of anxiety and also, could not remember what we talked about in each session, so couldn’t implement the tools and techniques to recovery. It might be helpful to know what testing, if any, the neurologist did. Was neuro-psych testing done? Was a brain MRI done? If those are normal and basic labs are normal, it would seem more like MBS. I have also seen situations where someone goes from totally normal in their early 80’s, undergoes a severe stressor which leads to chronic anxiety, chronic somatic symptoms and ultimately deteriorates into severe dementia and death. I don’t know if that would have happened anyway without the stressor and anxiety. I think lack of self-confidence and fear can really impair our abilities to focus and thus, to remember. Our brain can’t generally do math while we are busy fighting tigers all day! There was a study about 8 years ago that showed an ASSOCIATION between benzodiazepine use and risk of dementia, then a later study that clarified that the real risk was chronic anxiety, not the benzodiazepine use. Any treatment that decreases the amount of fear we live in on a daily basis is going to improve our body’s physiology and function, so I would encourage your patient to try and not focus on the memory problems – this will just cause more angst and fear as he is trapped in the “fear -memory loss- fear cycle”- and instead focus on “turning off the danger signal”. Having said that, if he is not getting enough oxygen via CPAP, that will also cause his brain to work suboptimally and lead to cognitive problems ….It is very impressive to see someone go from suffering from severe untreated OSA to suddenly being treated with effective CPAP – really night and day difference on their overall health and well-being. We need oxygen 🙂 If he is truly having oxygen deprived periods due to not using CPAP, it might be good to work on his CPAP phobia first.