Health - Does Ketamine do irreversable damage?

[Regretamine]

Over the last year swim has done alot of K, probably around 5-10 grams every week. Swim is trying to stop though now because he has really started to feel the damage it has done, for instance whole chunks of his memory seem to have gone which effects doing certain things because he's forgotten how to do them properly. Also his mind works alot slower. Swim is just wondering whether these problems are gonna be permanent, or will go away with time... Is there anyone here with enough experiance with Ketamine to tell me this? Thanks.