I have been depressed a significant fraction of my adult life. I am also a biologist who abhors the medical description of this problem. I don't even like the word 'mental illness'. This shit is not an illness, its a normal response to a fucked up life! Can I get at least some acknowledgment of this fact? The sine qua non for me was an issue of Nature a few years back that focused on depression, talked about how prev…
Unfortunately, there are two types of depression, neither of which seemingly have anything to do with one-another. One is situational depression, where you're unhappy because, well, shit sucks. The other is clinical depression which can happen completely independent of your life circumstances.
The main reason for this is that it's fallacious to think that your emotions are "completely independent of your life circumstances". They're symbiotic.
I was born into modest privilege and had an upbringing that was free of abuse or major trauma, and the only things that have gone severely wrong for me in life have been through my own poor decisions.
Yet I can now easily see how the depression I've experienced was due to a combination of living in a somewhat unhealthy environment and having a propensity to respond to that environment by becoming depressed and fatigued. I can now see the same applies to everyone else I know of who experiences depression.
The explanation you've given is embraced by mental health professionals as it allows them to justify attempting to cure it with pharmaceuticals and short therapy consultations, but as the data shows, that approach has a pretty low success rate.