Acute therapy is the treatment phase focused on treating the patient to remission. Acute therapy typically lasts 6-12 weeks but technically lasts until remission is reached (American Psychiatric Association, 2010). Full remission is defined as a two-month period devoid of major depressive signs and symptoms (American Psychiatric Association, 2013; Diagnostic and Statistical Manual of Mental Disorders, 5th Edition).

Continuation therapy is the four-to-nine month period beyond the acute treatment phase during which the patient is treated with antidepressants, psychotherapy, ECT or other somatic therapies to prevent relapse (American Psychiatric Association, 2010). Relapse is common within the first six months following remission from an acute depressive episode; as many as 20-85% of patients may relapse (American Psychiatric Association, 2010).

Maintenance therapy is the treatment phase that follows continuation therapy. The goal of maintenance therapy is to prevent recurrence of new or future episodes of major depression (Rush, 1999). The best candidates for maintenance therapy are patients who meet any of these criteria:

• three or more previous episodes of major depression,
• two episodes of major depression and rapid recurrence of episodes,
• older in age at the onset of major depression (more than 60 years of age),
• severe episodes of major depression, family history of a mood disorder, or
• residual symptoms (American Psychiatric Association, 2010).

Other risk factors for recurrence include the presence of a general medical condition, ongoing psychosocial stressors, negative cognitive styles and persistent sleep disturbance (American Psychiatric Association, 2010).

Maintenance therapy should also be considered for at-risk patients with double depression and patients with a comorbid anxiety disorder or substance abuse. Patients whose major depression has a seasonal pattern are also at risk for recurrence and may benefit from seasonal reinstatement of light therapy or antidepressant therapy. For patients on maintenance medication, contacts can occur every 3 to 12 months if everything else is stable (Oxman, 2002; Katon, 1999).

Relapse Prevention

The prevention of relapse is of primary importance in the treatment of major depression. From 50 to 80% of people who suffer an episode of major depression will have a recurrence, usually within two or three years (American Psychiatric Association, 2010). Patients who have had three or more episodes of major depression are at 90% risk of having another episode. Relapse prevention interventions resulted in 13.9 additional depression-free days during a 12-month period (Simon, 2002).

Psychotherapies. Focused psychotherapy through cognitive-behavioral therapy can reduce relapse by assisting patients with their depression-related beliefs (Teasdale, 2001). In addition, focused psychotherapy can significantly reduce symptoms and restore psychosocial and occupational functioning in patients with major depression (Leichsenring, 2004).

Pharmacotherapy. A Katon, 1996 study found that improving attitudes toward antidepressant medications, along with the patient's ability to handle medication side effects, are key factors in promoting greater adherence to maintenance treatment and thus greater likelihood of preventing relapse (Katon, 1996). For information on duration of pharmacotherapy post-remission to prevent relapse, see the "Duration of Pharmacotherapy" section in Pharmacotherapy.