As my wife (a child psychiatrist) often tells me "kids aren't just little adults."
It's funny how the negated converse, "adults are just big kids," does seem to be a fairly accurate statement, however. Not just in terms of maturity and playing Wii all the time, but in actual medical practice in psychiatry and otherwise. While most people pick med/peds for lame reasons, the ones that recognize the value of treating "pediatric" conditions in people who now live to be 40 instead of 14.
To the OP, yes, family docs and primary care pediatricians treat what they call ADHD and depression. And it's probably a good thing that they do, because psychiatrists are too few and too expensive for every patient with a behavioral or mood complaint to see a specialist. But most pcps are readily out of their comfort zone past low-to-moderate doses of stimulants or antidepressants, and few pcps have any business whatsoever prescribing a neuroleptic or an antiepileptic for just about any reason, even if drug companies have suddenly convinced everyone that Seroquel is an acceptable sleep drug.
PCPs also do not have the training to properly diagnose most psychiatric disorders, but many still do a pretty fair job anyway and deserve a lot of credit for their ability to do things they haven't been trained to do, and still recognize where their expertise is limited.
So yes, strictly speaking, family docs can do whatever they want. If they build their own hospital, they can do neurosurgery out-of-pocket, if they're willing to accept the liability.
Child psychiatry is a high-liability and a difficult field to do right. If you're interested in behavioral or mood disorders in children, the only ways you can really do your patients right is to train as a child psychiatrist, or do a developmental peds fellowship as a pediatrician. The latter option is severely under-explored by medical students, and while the fellowship does not offer much training in psychopharm, most of the psychiatric pathology and diagnostics are similar.
