There is Someone who is diagnosed with OCD, and takes anti-depressants as well as anti-psychotics to treat it. He is afraid that he constantly commits apostasy, because he is afraid if he ignores it and he actually did kufr that he will be held for it. He does ghusl 3+ times a day. What to do?

First of all, may Allah subhanahu wa ta'ala heal you and cure you. I advise you to continue with the doctors and follow their instructions. Islamically, what you have just described falls under a specific rule of thumb: never ever retake your shahada, and do not repeat anything that you doubt. The answer is always, always: yes, you are a Muslim; you are not a kafir. Even making ghusl (taking a bath) is not mandatory, it is preferred. Anyway, do not do this again. Do not retake your shahada. This is the rule that you and I have to agree upon: you are a Muslim no matter what. Ignore all of these thoughts. This is just waswasa. No matter how sure you are, keep in mind they call it "compulsive" for a reason. So, the rule of thumb that you must not break is this: do not ever repeat anything, whether it is your salah or your shahada, until inshallah tabarak wa ta'ala you are healed.