In clinical psychology (specifically the DSM-5), ABDL is considered a mental disorder only if it causes the individual significant distress, impairment in social/occupational functioning, or involves harm to others. For many, it is a benign lifestyle choice that brings comfort and happiness. Mental health professionals generally advise "watchful waiting" or acceptance therapy rather than conversion therapy, as attempting to suppress the interest often leads to increased distress.
To make sure I give you the most helpful response, could you clarify which of these you'd like me to focus on?