I thought the science was settled. A Decisive Blow to the Serotonin Hypothesis of Depression | Psychology Today
Almost as soon as it was floated in 1965 by Harvard psychiatrist Joseph Schildkraut, the serotonin hypothesis of depression—reduced and simplified by pharma marketing to the “chemical imbalance” theory of depression and anxiety—has been subject to critical research and found wanting.
The poor standing of the hypothesis in the scientific literature, however, barely dented its afterlife in textbooks, across clinical and treatment settings, and on mental health apps and websites. Nor has it dispelled the continued use of the phrase as “shorthand” between doctors and patients and in everyday settings, including for quite different mental states and conditions.
Of course companies that manufacture and sell this crap, I mean the drugs, are only interested in selling more drugs.
Apparently "informed consent" is also no longer a thing in medical ethics.
They asked more broadly of those repeating the discredited hypothesis, whether as metaphor or oversimplification: “Do you believe it is ethical to present a falsified scientific theory as a fact to a patient? What are the possible negative effects of doing so?”
A significant consequence they anticipated at the time was that patients would realistically “conclude that they have been misled.”
And the result is a population over medicated for reasons that are questionable. They only provide the numbers for the UK, but they are staggering.
“The popularity of the chemical imbalance idea of depression has coincided with a huge increase in the use of antidepressants,” note Moncrieff and coauthor Mark A. Horowitz in the study’s press release. “Prescriptions for antidepressants have sky-rocketed since the 1990s, going from being rare to a situation now where one in six adults in England and 2 percent of teenagers are prescribed an antidepressant in a given year.”
If this ever takes hold, pharmaceutical companies stand to lose a ton of money. Oh, and doctors need to stop lying to people.
So what causes depression? "stressful life events." They don't say what those are, but maybe they don't have to. Losing a job. The death of a parent. Etc. All the typical stuff life can and does throw at people.
I would say a lack of a foundation for your life, would also play into how you handle those life events, but that isn't scientific either. If the only meaning in your life is the size of your bank account, or the amount of granite in your kitchen, you are not going to fair well, when one of those curve-balls life likes to throw comes your way.