Yes, i'm at 20%, i'm super fatigued and get brain fog, I even passed out and crashed my truck. Believe it or not exercise clears that up for me. When I feel that way I get on a stair stepper or ride my bike, I get my heart pumping as much as I can. Drink cool water, do breathing exercises, tai chi moves and then sit and rest. This gets oxygen to my organs and brain. So, smile, watch things that make you laugh or feel good, stay away from sad movies and negative people. Take care of yourself, you deserve it, and you will feel better and cope with your health. Take care!

I’m not a dr…. But if you have been in distress for a while ,
Loss of oxygen to your brain from your heart can have some effect on memory , at least it did on me . It called hypoxia.
Good luck