This very insightful article from the NY Times explores the consequences of labelling a pre-school child with behaviour problems with severe mental illness. This US view is disturbing, from the ease of which anti-psychotic medication is prescribed off-license, to the pharmaceutical company who supplied promotional building bricks to use in the waiting room.
In the US, the idea of a Health Visitor is unknown. To me, it’s the first place to refer a parent and child with difficult to sort behaviour. I suspect it is also cheaper and safer.