[root_axis]

IMO, this hypothesis doesn't pass the smell test. One of the defining qualities of clinical depression is that personal success in life does not obviate the symptoms; there are many widely know examples of beloved and successful people being unable to overcome the burden of crushing depression.

[omniglottal]

Being beloved and successful does not negate negative feedback. In fact, rhetoric such as this is invalidating the experience of those who must thereby insist that, contrary to the signs you're seeing, they're actually feeling down, else they must further internalize the negative feedback which nevertheless exists in plethora. The notion that anyone could claim precisely what reasonably should bring another stranger happiness or resolve their depression is pure hubris. The defining qualities of this situation are all internal, and the externalities used in your measurement are correllative and either irrellevant or after-the-fact. A "smell test" one might consider is of empathy: if your mind ran quickly through various things which caught its attention, yet couldn't follow through with focus until resolution, negative feedback surely just recurs and piles up - it is neither sufficiently affected nor undone by positive feedback. OP's hypothesis smells true to me, but I choose to sniff the roots rather than the flower when we're looking for a cause more than an effect.

[kemiller]

Well, first of all, I didn't say it was the only cause for depression; it's a condition that comes in lots of different flavors and this is only one.

Second, to elaborate a bit more, having to constantly manage your brain in order to get it to do what you need can be exhausting. Any success you achieve feels like it's extremely tenuous, and I'd say most AD(H)D people have had an experience of doing well for a while and then everything falling apart. So nothing ever feels safe. The negative feedback you get will tend to reverberate much more loudly in that environment than the positives.

[sizzle]

I co-sign everything written here as

[Eldt]

I never invited you people into my head and I don't like it

[kemiller]

I understand this, lol. But you can also take heart that you don't struggle alone. You might be surprised at how many places you can be open about this stuff and have positive things result.

[nth_order]

Another complicating factor is that it is assumed that there are a few different subtypes of depression. For example with and without psychotic features. Another subtypes is the "atypical depression", which actually has, in contrast to classical major depression, "reactive mood" and a high degree of "rejection sensisitivity": https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2990566/