Is difficult. With young children how do you tell whether a child has mental health issues, or is acctually being screwed up by uncaring parents?

It is certainly possible for children to have mental health problems. The brain is just like any other organ, problems can occur. A early diagnoisis of aspergers for instance makes it easier to treat, helping the parents and child.
To imagine that every other organ in the body can have problems except the brain is illogical.