I'm not exactly sure what this phrase mean: "the purpose of _ is to delay the time to occurrence of mood episodes ..."
My guess is that it means that _ increases the amount of time between episodes.
"postpone" seems to fit.
"the purpose of _ is to postpone the occurrence of mood episodes ..."
- postpone - (vb) To cause or arrange for (an event) to take place at a time later than the time at which it was originally supposed to happen.
This new drug is supposed to postpone the occurrence of anxiety attacks.
She has decided to postpone the meeting.
Our departure was postponed because of the weather.