It's really bizarre to me how fixated people are on viewing depression solely through the "disease with a biological cause" lens. Even in this article, which acknowledges the serious flaws in the serotonin hypothesis, all the alternatives they explore are around other biological things like other neurotransmitters, inflammation, etc.
Maybe more people are anxious and depressed than in the past because modern life really sucks for a lot of people. I'm not saying that's a simple thing to fix, and certainly there is a biological component for some people...but the idea that societal changes are increasing rates of anxiety and depression seems way more plausible than there being some sudden and mysterious shift in the biology of a significant percentage of the population that needs correcting via medication.
Here is a lecture by Robert Sapolsky, an extremely well-regarded researcher, that goes over some evidence on depression being a disease:
https://youtu.be/NOAgplgTxfc
It's been a while since I've seen it, but I recall his evidence including some rather striking non-behavioral symptoms, like changes in sleep cycles.
To address your specific thoughts on it, his position (paraphrased from memory) is that social stressors like you describe cause elevated cortisol, which causes depression - such that your position that "modern life really sucks" is not incompatible with a biological cause.
It's extraordinarily interesting in a lot of other ways - definitely worth a watch in spite of the length.
Oh yeah, certainly, being depressed is correlated with all kinds of changes in biology. I'm not saying it's like "just in your head", but the question is, do those changes lead to being depressed or does being depressed lead to biological changes?
Of course that question is an oversimplification since the answer is certainly some of both; but the prevailing wisdom seems to be that it's mostly/all biological changes leading to feeling depressed, whereas I'm not convinced the scales don't lean more in the other direction, at least on average.
EDIT: but as to your point about stress leading to elevated cortisol levels, to me that's clearly not a biological cause. The cause is stress, and the elevated cortisol levels are an effect of the stress. It's not like the hormone levels just went up all by themselves due to some genetic abnormality or something; if they did, then yeah maybe that's a biological disease that warrants some kind of chemical correction, but that's not at all what we're talking about.
If you had crippling anxiety because someone actually was trying to kill you, don't you think you'd have changes in your sleep cycles? Why does that have to indicate some change that is based purely on chemical imbalances that are not caused by external factors?
Not disagreeing with you I think depression is a constellation of things but anhedonia in my opinion definitely has a biological cause because it comes and goes.
This is really faulty logic. Your emotions moving in cycles is not in any way proof of some purely biological issue. Non biological stimuli like external stressors also come and go.
It's not faulty logic at all. Scientists have known for a while that your ability to experience pleasure is a result of certain biological processes.
"Recent findings in the field of neuroscience have, however, demonstrated that a single functional circuit, incorporated inside the broader dopaminergic mesocorticolimbic system, seems to be involved in the various experiences of pleasure"
Going back to your accusation of "faulty logic": an interruption in the ability to experience pleasure, which is established to be controlled by biological processes, having a basis in a biological process would be deductively valid logic. Anhedonia is an inability to experience pleasure.
It's not faulty logic at all. Scientists have known for a while that your ability to experience pleasure is a result of certain biological processes
Well of course on a certain level your ability to feel anything is the result of biological processes, but that doesn't mean that the specific things you feel aren't a result of the specific experiences you've had.
Nobody in this thread is arguing that feelings happen completely independently of biological processes, but there's a hugely important difference between "I had a bad experience that altered my feelings, and that's reflected in my biology" vs "my biology just did something of its own accord that had nothing to do with my life circumstances, and that change altered the way I feel".
You seem to be arguing that because anhedonia correlates with certain biological changes, that it must be caused by those changes. That could be true (and probably is true in some cases) but it does not necessarily follow that it is always true, or even true the majority of the time; the causation could could flow in a different direction.
Let's come back to my original argument that anhedonia, which is a core feature of depression but is not the same as depression, is caused by biological processes. Do you have evidence to say that it is not?
Maybe more people are anxious and depressed than in the past because modern life really sucks for a lot of people. I'm not saying that's a simple thing to fix, and certainly there is a biological component for some people...but the idea that societal changes are increasing rates of anxiety and depression seems way more plausible than there being some sudden and mysterious shift in the biology of a significant percentage of the population that needs correcting via medication.