DechanDawa - yes, that is correct. They might diagnose and prescribe medication for Depression. Thing is, mental illnesses like Bipolar often present at Depression (when do we ever go to a doctor hypo/manic and say hey Doc, I'm feeling terrific I think something is wrong).

A family doctor here will generally refer the patient to a psychiatrist which is a 3-4 mos wait (at least here). They will try to treat their patient in the meantime.

But all in all, a GP is merely a stopgap measure.