Definately an important and interesting question - just thought I'd chime in my two cents worth.

I often get asked by patients how long they need to stay on meds. I generally consider a number of factors to guide me, ultimately to decide how vulnerable or at risk the individual is. I certainly look at the number and length and severity of episodes, and whether they were associated with strong suicidal ideation. If someone has made a significant suicide attempt, I think they should stay on antidepressants indefinately, given how high the risk is of eventual completed suicide among people with a history of attempting. 3 or more significant episodes of major depression, and I'll generally recommend indefinate continuation of meds. I consider other risk factors, for example whether they have a problematic marriage, an unstable or stressful job, substance abuse,poor self esteem, a personality disorder (or traits of one), etc. Also, I think about how they did with their course of CBT - did they really learn how and when to use thought records, etc, and did they make progress in shifting underlying assumptions and core beliefs?

I agree that for some people the MBCT program is a great option. I often refer patients to it, since Zindel Segal, one of the originators of it, is here in Toronto.

I like to draw a circle for patients, write inside "risk of relapse", and then write as many things as possible that might contribute, for them. That way, I'm considering each individual's risk factors, and I'm getting their input. Often the list will include getting regular exercise, proper sleep, balance of work and play, meds and self esteem. Other factors might depend on the person, for example if financial struggles often lead a given individual into depressions, their relapse prevention work might need to focus on obtaining stable employment, paying off debt and curbing impulse spending. Someone else, who for example tends to get used and taken advantage of, might need to work mostly on assertiveness and self esteem. One woman I worked with needed to focus more, when she wasn't depressed, on setting limits with her husband and kids, and organizing her day better so as to not feel frazzled and overwhelmed too often. Another patient, for whom substance abuse played a big role in his depressions, needed to have a strong set of tools in place to prevent drinking.

I think it is a complex question, without a black/white answer - like most things