Major depression can be a devastating—even life-threatening—condition. Thousands of studies have examined what works in restoring hope and vitality. 

I've compiled 27 important facts about depression treatment, based on the latest research. Whenever possible I've relied on the most recent meta-analyses which combine results from all relevant studies to establish general trends. 

Take care in interpreting these findings, as research in these areas is ongoing.

Medication and cognitive behavioral therapy (CBT) are equally effective in treating depression. Medication can help with severe depression even as much as CBT. 

There is a very strong placebo effect in depression treatment. The average person in a clinical trial does just about as well on placebo as on medication—a 40 versus 48 percent reduction in symptoms, respectively, based on a major review.

Chronic and more severe depression responds better to a combination of medication and therapy. Medication plus CBT is more effective than meds alone, and medication adds additional benefit for those receiving CBT. For mild, non-chronic depression, a single treatment typically works as well as the combination—and avoids the additional time, effort, cost, and side effects.

About 1 in 8 adults in the US are taking medications that are prescribed for depression. Two-thirds of these individuals are taking a selective serotonin reuptake inhibitor (SSRI) like Prozac or Zoloft.  

CBT is not the only type of talk therapy that works well in treating depression. Psychodynamic therapy—which is based largely on a Freudian understanding of the mind—has gotten a bad rap in the era of evidence-based treatment. However, there's growing evidence that short-term psychodynamic therapy is helpful, as is a more general type of treatment called "nondirective supportive therapy." The Society of Clinical Psychology—a division of the American Psychological Association—keeps a list of treatments with the strongest research support. 

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Exercise can be a powerful antidepressant treatment. Researchers have found benefits of walking, jogging, running, resistance training, and other forms of movement. More intense activity generally leads to greater depression relief. 

Improving diet may be an effective way to relieve depression. A study from earlier this year found that educating people about better eating habits could lead to big reductions in depression. Participants were advised to increase consumption of vegetables, whole grains, legumes, healthy fats, and lean proteins, among other foods; and to reduce heavily processed and sugary foods, as well as alcohol.

The addition of omega 3 fatty acids is not considered an effective treatment. A review from 2007 had suggested the these supplements were effective, but cautioned that it was "premature to validate this finding" as more research was needed. A more recent meta-analysis found minimal effectiveness of omega 3s compared to placebo—although it's worth noting that the same has been found for medications for depression, and "placebo" doesn't mean there was no benefit.

Self-directed CBT can be an effective treatment for depression. It tends to be somewhat less helpful than partnering with a therapist, and is probably most appropriate for those with mild to moderate depression. A hybrid approach—self-help with some guidance from a professional—can be just as effective as face-to-face therapy.

There is a high risk for relapse after discontinuing medication for depression. In a meta-analysis of 31 trials, people who were switched to placebo had about a 40 percent risk for relapsing in the following 4 to 36 months; continuing on medication reduced that risk to 18 percent. 

CBT is better than medication at protecting against depression relapse once treatment is over. That said, nearly one in three individuals will relapse within a year after receiving CBT. Many fewer relapsed if they received additional CBT sessions, which underscores the importance of continuing to practice the tools learned in treatment. 

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"Positive psychology interventions" can relieve depression symptoms. This finding is not surprising since these types of interventions are "aimed at cultivating positive feelings, positive behaviors, or positive cognitions"—things CBT also emphasizes. 

Behavioral Activation is one of the simplest and most powerful treatments for depression. This form of CBT focuses on increasing the rewarding activities in our lives, so we find greater connection, enjoyment, and sense of accomplishment. The changes lead to big improvements that last well after treatment has ended. 

Interpersonal Therapy is a highly effective treatment for depression. Relationships affect our well-being, for better and for worse. Positive changes in the ways we relate to others can lead to a major mood boost, and can also help prevent relapse.  

Psychotherapy is an effective treatment for depression in kids and adolescents. Improvements tend to be modest in size, with no apparent advantage for CBT over other therapies for this age group. More work needs to be done to find ways of making the gains stick, as they tend to fade over time. 

Medication has a small advantage over placebo in treating depression among adolescents. A meta-analysis revealed a 10 percent greater response to medication than placebo (60 percent vs. 50 percent).

Medication has no significant advantage over placebo in treating depression among children (ages 12 years and younger).

The use of SSRIs among young people doubles the risk for suicidal thinking and suicide attempts. The rates were two percent among placebo groups and 4% among those who got medication. 

Hypericum perforatum: St. John's wort

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St. John's wort can be an effective treatment for depression. It's better than placebo in treating mild to moderate depression, and equally effective as of medication with fewer side effects. 

Depressed individuals with a personality disorder are twice as likely as those without to have a poor treatment response. A personality disorder is "an enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual’s culture, is pervasive and inflexible, has an onset in adolescence or early adulthood, is stable over time, and leads to distress or impairment"; examples include borderline, narcissistic, dependent, paranoid, and schizotypal. This effect held for treatment with either medication or psychotherapy. 

Structured CBT delivered through the Internet leads to small but significant improvements in depression. Assistance from a therapist is likely to boost these programs' effects. Some of the programs that work are available to the public for free, such as MoodGYM.

In primary care setting, collaborative care leads to better depression treatment outcomes. In collaborative care, mental health specialists and case managers work alongside primary care doctors. Specific interventions might include phone calls to patients to encourage medication compliance and having psychiatrists supervise case managers. 

Childhood maltreatment is linked to more recurrent depression and less responsiveness to treatment. Maltreatment can include abuse, neglect, or violence in the family. More research is needed to understand how these experiences affect the course of depression.

Adding CBT to medication for depression in adolescents brings little additional benefit. Combined treatment does seem to relieve impairment more than drugs alone. 

Similarly, adding medication to psychotherapy for depression does not improve treatment outcomes in children and adolescents. However, authors of a recent meta-analysis summarizing these findings concluded that "there is very limited evidence upon which to base conclusions about the relative effectiveness of psychological interventions, antidepressant medication and a combination of these interventions."

The SSRIs and older medications like the tricyclic antidepressants produce similar benefits. While treatment outcomes are about the same, SSRIs tend to produce fewer side effects, making them better tolerated. 

Mindfulness-Based Cognitive Therapy (MBCT) prevents depression relapse, particularly among those with 3 or more episodes of depression. Those who got MBCT were 34 percent less likely to relapse, an effect that's comparable to staying on medication for depression.