Extreme brain fog and vision deterioration mouth taping

I have been using my BMC APAP for about 6 years now. I have always struggled with brain fog that got slightly better when I started using my APAP.

The last 3 months or so I have noticed waking up with a very dry mouth and have been able to realise it's because air started flowing through my mouth while I'm sleeping. I have no idea why this started all of a sudden. It could be coincidence but with that I have noticed a decline in my brain health, my vision has gotten to the point where I can barely work and my brain fog is unbearable. I've been to the Dr multiple times and I've done a list of blood tests with nothing showing out of the ordinary.

I have tried mouth taping with the 3M tape last night but still woke up with a dry mouth and noticed air could still pass through my mouth. Has anyone had a similar experience?

I have adjusted my machine to lower and higher settings to see if it will work, but it doesn't.

Hi, not familiar with your machine (where do you live?) but does it have a humidifier that you use? Have you got any nasal issues? And though you say you've seen the doctor, has your glucose been checked lately - wondering about your vision problems... unless you're sure e.g. that they're from air leaks from the cpap - there are fixes for that. Are you using any new meds?

My box of equipment came with a neoprene chinstrap apparatus with the logo "Morpheus ByCPAPology". The good news is that it works. The bad news is it's hot (neoprene) and adds to the strapped in effect of a full-face mask. It wasn't bad till summer arrived. Most nights I can go w/o it, but some nights I end up with the lower part of the full-face mask in my mouth. I never know what kind of a night I'm going to have so it's a crapshoot.
I've been using CPAP for a couple of months, still working out some of the nuances.

To the OP: I'm assuming you currently use a mask with a nose-only interface; is that right? If so, you may want to think about switching to a full-face mask.

Before that, though, you might want to try wearing a soft cervical collar, which will support your lower jaw from below. That plus tape might do the trick for you. Some people use several layers of micropore tape.

Without data it's hard to know, but you may be having more day-time problems if your mouth leaks are preventing you from getting adequate PAP therapy during the night. I skimmed the user manual for your machine, and it looks like there's an alarm that goes off if you have major leaks. Is the alarm function on your machine turned on?

Also, do you have any way to know whether your AHI is increasing, or what its components are (obstructive apnea, central apnea, hypopnea)?