Last time I asked a question there was MHO icon beside comment icon in the opinion threads - You click on that to award MHO to a guy or girl ( There are two MHOs now, Most Helpful Guy and Most Helpful Girl )
You do not get to pick mental health as a category on here anymore. You can however choose health & fitness which seems to be in some cases the same. They took it off because it didn't seem necessary to have a category such as that one alone.
Health & Fitness fits into many types of branches that relate to that.