I am rather disappointed by much of the discussion in these comments.

The HN community has always taken pride in being careful, analytical and data-led. If someone were to advocate an unproven cancer therapy based on anecdote, they would rightly be harshly criticised.

The evidence base for SSRIs is extremely poor. The most favourable metastudies indicate only a very mild benefit, similar to that of many non-drug interventions like exercise or conversation with friends. Other metastudies show only a weak effect in the most severely depressed patients. There is known to be a very serious problem of publication bias, with major statistical irregularities indicative of the non-publication of unfavourable trials.

We feel confident in making statements about the nature of depression, but in truth we know almost nothing with any degree of confidence. The long-held serotonin hypothesis has proven to be completely baseless and there is no good evidence that depression has a neurochemical etiology. fMRI data is often used to make the case that depression has neurological rather than psychological origin, but this is very poor reasoning; The brain is not merely a passive vessel for the mind and environmental influences can cause substantial structural changes to the brain, as seen in chess players, sportsmen and myriad other groups.

It is entirely possible that the idea of depression is itself a cause of depression, in much the same way that the western presentation anorexia nervosa has been imported into Chinese culture and is slowly replacing the far more common indigenous eating disorder, which presented as idiopathic digestive problems rather than a psychological aversion to food based in body image. It is entirely plausible that the belief that low mood is a medical disorder which cannot be ameliorated by the patient is itself pathological.

I believe that the only statement we can make about depression with any confidence is this: We aren't sure if "clinical depression" describes a phenomena that can be meaningfully thought of and treated as a disease, but we do know that if you do something that you believe will make you feel better, you will feel better.