https://pmc.ncbi.nlm.nih.gov/articles/PMC8111503/
I'm concerned by the pervasive thought pattern held by many, but especially engineers: that you can think your way out of any problem. This bias leads to preferential seeking and over-prescribing of therapeutic treatments.
Yet how many people who self report depression are also satisfied with the various external factors in their life? Perhaps the correct framework is: a healthy environment is the cornerstone of a healthy mind.
I'm sure it's possible with enough meditation and medication to achieve enlightenment whether you're exiled in the Siberian wilderness or locked up in a castle dungeon, but to do so is working against the grain of nature. Unhealthy environments have a negative impact on individual health. The Foxconn "safety nets" come to mind.
Though I could be mistaken, perhaps zoo animals are only depressed because we haven't fully translated "mindfulness" into ASL.