My Brother Had What He Thought Was A Cold Which

My brother had what he thought was a cold which rapidly progressed to where he became disoriented and was taken to the ER and was diagnosed with double pneumonia and immediately placed on an IV of antibiotics and eventually Legionnaires was ruled out as was Lyme but after four days of being on oxygen, antibiotic he had to be intubated for seven days and then extubated and now is confused. Can’t remember the color of his house, thinks his daughter is still a child, etc... Is this permanent?