Look at the "Sticky" section, under the topic of "Cardiovascular and Metabolic Effects of OSA". There are lots of informative articles there.
And yes, your dh's sleep apnea is causing oxygen deprivation. That's what apnea does. Simply put, not breathing (apnea) = no air getting into lungs = no oxygen getting to brain. When you have untreated apnea, it is as if someone is standing over your bed all night, putting a pillow over your face and suffocating you for at least ten seconds, several times an hour. It can add up to several hundred "suffocations" over the course of a night! That puts tremendous strain on your lungs, heart, brain, virtually your entire system. And personality changes can be part of that.
Please read the articles and try to convince your dh to use his machine. It's not just a matter of noisy snoring; it is a life threatening condition that needs to be treated.
Resmed Vpap Adapt SV Enhanced, Respironics Fit Life total face mask, Forma full face mask.
Complex apnea, original AHI 80