It likely has everything to do with the regional rules than a psychiatrist's unwillingness to do so.

I also am thinking this has much to do with puberty. Bipolar is an illness of a chemical imbalance in the brain. Such an imbalance could similarly be attributed to chemical changes owing to puberty. There are additional external factors that are more prevalent - particularly social - that could be affecting mental health (are social difficulties the cause of emotional problems or is it the other way around?).

My understanding though is that a psychiatrist will treat the symptoms.