Maybe not mental health (health relies on norms and such that lose meaning in the face on an anomaly), but something along the lines of a mentality/mental category. Obviously the category title would have to be better than that.
A category which panders to the need of depression, but also includes the moments of instability and bliss and confusion which are universal; not merely confined to a category for the pessimists and all their woes, or a category that be derogatory.
While there is indeed a desire and want of a depression category, it has the potential to be an extremely dark and dangerous road. Problems of narcissism and anti-criticism, of trolling and attacking the vulnerable, poems ignored for being part of a group that people find boring and therefore ignoring hidden gems, of criticism turning into psychology focussed on author not subject, and the problem that in my view depression is more personal than other things.
Though of course such problems may not ever occur, and you could well argue for more problems of categories we already have, like Upbeat having to be upbeat, erotic bordering on smut in some cases, and Miscellaneous being rather vague at the best of times. Yet the point is that with a depression category it is more likely that problems will have deeper impacts and repercussions than other categories. Disagree with an Anger or Erotic poem and criticise it too much and the author may well make other, whereas with a depression category the author may well become an ex-author.
Or maybe I just do not want to have to go back over a lot of my poems and change them to their true 'Depression' category. I share my sorrow with the idea that no one feeds it but at least it is there. Yet in the face of Despair in an overt and social setting I am driven to fight against it because it is a scourge that must be destroyed to preserve the species.
Plus next there may well be demands for forum posts being categorised, such as Long or Rambling....