Many people struggle with depression, and I've been trying to formulate some general advice for treating it as a part of my work for Cognito Mentoring. I'm hesitant to write about the subject on account of lacking professional expertise, and so am especially interested in getting feedback on my thinking on the subject. I've written up some tentative thoughts below. The reader being addressed is somebody who's struggling with depression, with a special focus on high school students.

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The research on the efficacy of different depression treatments is only moderately strong. I'm not confident in my remarks below: they reflect an attempt to come to the best conclusion possible with the evidence available.

• Any given treatment of depression only works for a fraction of depressed people, suggesting that causes of depression may be diverse. 
• Cognitive behavioral therapy (CBT) stands out for its combination of efficacy, potential for producing lasting changes, low cost, and absence of averse side effects.
• It's worth experimenting with different treatment methods to see which works best for you, with the possible exception of antidepressants.
• Combining treatment methods may be more impactful than applying one individually.

Cognitive behavioral therapy

According to The empirical status of cognitive-behavioral therapy: A review of meta-analyses, there's a strong base of evidence that CBT has a large effect of reducing depression on average. There's evidence that the benefits extend beyond the duration of the treatment. Studies generally seem to show that CBT is as effective as antidepressants at reducing depression (some find that CBT is more effective, but the evidence is unclear).

CBT has the advantage that one can learn to do the exercises on one's own, without the expense of a therapist or a psychiatrist. The evidence for the efficacy of self-help CBT materials is weaker than the evidence for the efficacy of therapist-administered CBT, but this may reflect insufficient commitment on the part of patients who were assigned to use self-help CBT materials. The clinical effectiveness of CBT-based guided self-help interventions for anxiety and depressive disorders: A systematic review finds that for self-selected users of self-help CBT materials, the treatment was efficacious (though the quality of the studies was not high). If you're sufficiently committed, the expected benefits that you stand to gain from self-help CBT may be enhanced substantially.

A book for learning CBT on your own is Feeling Good: The New Mood Therapy by David Burns.

Exercise

It's widely believed that exercise alleviates depression. There's an intuitive basis for thinking this: exercise often gives one a runner's high.

In the Cochrane review Exercise for depression, the authors find that on average, studies show a moderate-sized effect, but that when one restricts consideration to the highest quality studies, one sees a significantly smaller effect, suggesting that the efficacy of exercise for treating depression may be overstated.

The main downside to exercise is that it takes time, but it may be worth it even if the effect size is small if alleviating depression is sufficiently high priority for you.

Talk therapy

Talk therapy has been shown to reduce depression on average. However:

• Professional therapists are expensive, often charging on order of $120/week if one's insurance doesn't cover them.
• Anecdotally, highly intelligent people find therapy less useful than the average person does, perhaps because there's a gap in intelligence between them and most therapists that makes it difficult for the therapist to understand them.

House of Cards by Robyn Dawes argues that there's no evidence that licensed therapists are better at performing therapy than minimally trained laypeople. The evidence therein raises the possibility that one can derive the benefits of seeing a therapist from talking to a friend.

This requires that one has a friend who

• is willing to talk with you about your emotions on a regular basis
• you trust to the point of feeling comfortable sharing your emotions

Some reasons to think that talking with a friend may not carry the full benefits of talking with a therapist are

• Conflict of interest — Your friend may be biased for reasons having to do with your pre-existing relationship – for example, he or she might be unwilling to ask certain questions or offer certain feedback out of concern of offending you and damaging your friendship.
• Risk of damaged relationship dynamics — There's a possibility of your friend feeling burdened by a sense of obligation to help you, creating feelings of resentment, and/or of you feeling guilty.
• Risk of breach of confidentiality — Since you and your friend know people in common, there's a possibility that your friend will reveal things that you say to others who you know, that you might not want to be known. In contrast, a therapist generally won't know people in common with you, and is professionally obliged to keep what you say confidential.

Depending on the friend and on the nature of help that you need, these factors may be non-issues, but they're worth considering when deciding between seeing a therapist and talking with a friend.

Light therapy

If your depression is seasonal in nature, you may benefit from light therapy. According to The Efficacy of Light Therapy in the Treatment of Mood Disorders: A Review and Meta-Analysis of the Evidence

Randomized, controlled trials suggests that bright light treatment and dawn simulation for seasonal affective disorder and bright light for nonseasonal depression are efficacious, with effect sizes equivalent to those in most antidepressant pharmacotherapy trials.

The Cochrane review Light therapy for non-seasonal depression finds that even for non-seasonal depression, light therapy reduces depression on average, though the effect is modest.

Antidepressants

The Cochrane review Newer generation antidepressants for depressive disorders in children and adolescents found that antidepressants increased recover rates from 38.0% to 44.8% (over a specified duration) relative to a placebo. This understates the capacity for anti-depressants to reduce depression, because placebo treatment is also better than no treatment, and if one antidepressant doesn't work, you can try another one.

If you're an adolescent, the case for using an antidepressant is weakened by the fact that antidepressants are thought to increase the risk of suicide in adolescents. Some evidence for this comes from the Cochrane review above, which found that antidepressants increased suicide rates by 58%. The Food and Drug Administration requires that manufacturers of antidepressants include a warning that antidepressants can increase the risk of suicide in children, adolescents and adults under age 25. See antidepressants and suicide risk for more information. The size of the increased risk in "absolute" terms varies from person to person, because some people are more likely to commit suicide than others. But in a given case, the increased risk of suicide may not be worth the potential benefits. 

If you're under 25 years old, particularly if you're an adolescent, it seems reasonable to try other methods of treatment before considering antidepressants.