Why do doctors want to treat depression before they start...

Why do doctors want to treat depression before they start considering neurological disorders (adhd etc)? They say it’s so they can “rule the depression out” but I feel like it fails to factor in that symptoms of neurological disorders left untreated can result in psychiatric disorders. Maybe my depression is so treatment resistant because it takes me three hours to do a thirty minute task and I’ve been living this way since childhood, and maybe my bpd developed from abuse as a result of this reduced efficacy. Like I understand that you want a plan of action but why the resistance to the plan where you take my concern about my cognitive symptoms seriously? I feel like a lab rat instead of a patient.