Clay was forced into the Animus by Abstergo to obtain information from his DNA, to a torturous amount. He suffers from the Bleeding Effect, suffered- [hard to tell what tense to use when you've recently seen him back from the dead] and because our inside person didn't get him out he ended up committing suicide.
Daniel Cross was another similar case, and although the Assassins tried to help him his situation turned sour. [The sleeper agent thing didn't help either.] To a degree though, therapy and medication can help. But we're not going to get that deep into it-- we should be alright. Just giving all the facts.