Obviously this is not as bad as Mr Nad's Stroke, but I want to tell my experience with brain damage, as an illustration that synaptic pathways can be consciously worked onto change the state of your brain, even if the NUMBER of neurons you have doesn't change/keeps reducing. I'm sorry I don't feel up to telling the longs story.
In 1998 I had a massive and immediate reaction to a common SSRI, even though it's side effects were NOT supposed to be permanent, I came off it after I developed an extremely incapacitating stutter. The stutter stayed with me. It took me three years of slowing my speech right down and thinking hard about it to gradually reduce, and finally eliminate the stutter. I still now relapse into a very bad stutter when I'm very emotionally upset, and sometimes when my body is very tired. So basically it took me three years to retrain myself how to talk, and I consider myself fully healed in that department. The relapses on special occasions are a small price, and are actually useful in telling me and others how very upset I am about something, or how wasted my body is.
As well as the stutter I had started with extremely loud and prolonged Tourette's like symptoms whenever I had flashbacks, and I flashbacked incredibly more often than I used to. Often once every two minutes for hours on end. The Tourette's like symptoms were mostly verbal, but sometimes physical. When I just tried hard to suppress my vocalisations, they'd sublimate into convulsive physical motions instead, which were often dangerous to anyone sitting with me or lying next to me. The verbalisations started out for months as loud inchoate howling/screaming, and as I worked on controlling them, turned into loud swearing, and then largely settled into exclamations of "I HATE ME!". Occasionally (for an amount of occasionally considering they were happening every two minutes) I would spew out strings of swearwords instead. My current partner's favourite exclamation ever was "Slutmonkey".
Push-to-talk is SO my friend.
I considered it a personal triumph when I turned "I HATE ME" into "I HATE YOU". However that was even more psychologically wearing on the people I lived with. And there is no doubt my symptoms took a massive psychological toll on the people I lived with. Just trying hard to suppress these flashbacks or verbal reactions to them did ameliorate them, but not really by that much. It turned out that doing "Mindfulness" exercises for ten minutes a day reduced them by 95%. "Mindfulness" is very like a particular set of meditation exercises. If I don't do them every day, my flashbacks and Tourette's-like vocalisations/motions start to increase again in number and severity. I've got them down to the point where all I do when I flashback sometimes is wince heavily and curl down on myself a bit. I turned "I HATE YOU" into "I love you!". It doesn't come out always as "I love you", as it is sometimes still a squeak of pain, or a string of swearwords, or back to "I hate me". However, so far I have my partner fooled that my tourette's exclamations of "I love you!" are voluntary declarations of love aimed at him. I decided not to disillusion him on that one, and that makes us both more happy and relaxed.