Re: The Cerebral Palsy study - As I understood that study Kelly, it was providing support to the idea of multiple causation of CP. I don't think they were suggesting that birth trauma is less positively associated with CP, but rather adding to our understanding that there are other variables affecting the brain and nervous system that are also significantly associated with CP. Most of the studies (due to ethical considerations) have to be designed using a non-experimental design, and as such cannot infer causation anyhow.

Re: Autism. I think that 'better' (or more enthusiastic) diagnostics definately play a part in the apparent increasing incidence of autism. Keep in mind that the DSM and ICD are diagnostic tools that were developed by committees of psychiatrists and medical practitioners to explain and justify what they see (common patterns of behaviour). We need to be careful when we talk about developmental and psychiatric diagnoses. It's not the same as diagnosing diabetes whereby there are clearly defined and accepted physiological markers that can be physically seen. The chance for misdiagnosis is much greater for psychological and developmental disorders than for any other medical conditions. There is also a lot of pressure on schools and parents to 'seek' diagnoses to 'explain' deviant behaviour (that is, behaviour that deviates from the norm). I have known paeditricians and GP's to use the term 'autism spectrum' in preference to ADHD, knowing that the child will only recieve financial support/funding with the former diagnosis. So in addition to a fairly complicated, ambigous diagnosic criteria there is a strong social & political incentive for making one diagnosis over another. This is not because the medical profession are being deliberately sneaky - they are just seeing the day to day reality of families who really need help, and they know what's needed in order to get it for them. I cannot register a person with ADHD with the government department I work for. I can (within certain stringent guidelines) accept an Autism Spectrum Disorder diagnosis.

Again, retrospective, non-experimentally designed studies are problematic. I think we're barking up the wrong tree seeking to understand diagnoses such as these. I think we should be focussing on the individuals who are stuggling in our society, asking them and their families what they need, and tailoring our responses to each person and their unique needs. Stigmatising labels are of no real use (aside from access to funding - but that is a systemic issue, not a medical concern).

In terms of where all the adults with ASD are, I work with many of them. They are also grossly over-represented in the criminal justice system unfortunately. Social norms and rules can be very confusing to the ASD adult - especially those who have not been accurately diagnosed, or who haven't had access to early intervention, and concrete guidance in negotiating the strange, sometimes very abstract world we live in!