There are three groups of people who have depression: one group will have one episode and will never have it again; a second group will have episodes separated by long periods of time (up to 10-15 years) and do not need to be on medicine between the episodes; the third group has the return of depressive symptoms quickly if off medicine. The third group benefits from taking medication long-term. It is not possible to predict when people are having first episodes which group they will be in, so close monitoring and ongoing treatment is important.