Usually it is necessary to ask for professional help when depression and other symptoms have continued for a time beyond which "normal" depression has previously lasted and has been accompanied by the inability of the patient to function in all the usual and necessary roles- for example, as an employee, parent, spouse or friend. The purpose of help is to find out whether treatment would be expected to shorten the length of the illness and if so which of the range of specific treatments would be most suitable and likely to be most effective.

Reasons to refer a patient to a mental health team is when someone is in a severe condition, failing to respond to common treatment, complicated by other factors such as personality disorders, or presents particular risks.