There are two fundamentally different groups of diseases characterized by progressive memory loss. The first group is lacunar dementia (as a result of damage to the vessels of the brain). It is characterized by a slow deterioration in memory and the "sharpness" of the person's traits, ie. if a person was thrifty, he will become a curmudgeon; if he was caring, he will torment you with overprotection. And he will not get rid of the complexes, since with this type of dementia, information closely linked to the personality leaves in the last turn. The second group - total dementia (with Alzheimer's disease, neurosyphilis, etc.), on the contrary, is manifested by the disintegration of the personality nucleus, his behavior completely changes. All the complexes and problems will disappear here. A person becomes euphoric, does not control his actions, to the point that he can start urinating on the floor simply because he does not want to go to the toilet
I'm not a professional in this matter, but I observe the life of a distant relative. He lived his whole life with a fear of airplanes, and now, when he has Alzheimer's, he is completely calmly flying to his son in another part of the country. True, she no longer recognizes her son.