Details?
It is a "care allowance" from social.
I know there are some children that are seriously affected with this condition but I also believe there are a large number where it is simply bad behaviour that the parents cannot control.
Catch up will you? It's called DLA (disability living allowance) and it would not be awarded for ADHD alone. There would be other underlying problems, possibly exacerbated by the ADHD, such as ODD, OCD, ASD, GDD, SPLD etc., etc.
DLA is not awarded for medical conditions, it is based on how much additional assistance a person needs and what they need assistance doing. Some with ADHD alone are awarded DLA, some are not - all depends what their individual needs are.