Originally Posted by DrFishNips
Quickly? I was sitting in the psychiatrists office for 5 hours straight. My mother was there too. I'm not looking for opinions though I'm looking for solid evidence. I watched a documentary where they compared EEG's of neurotypical people to people with aspergers and they can distinguish aspergers from neurotypical due to activity of certain areas of the brain.
"Quickly" meaning that an adolescent or adult patient might visit their clinician multiple times over many months before a firm diagnosis is made.
In general, if they think you might be mildly autistic, they will give you that opinion but have you come back for further studies in order to make an "official" diagnosis. It's all heavily reliant on what the clinician gets to know about you and your behavior over the course of time ... Especially if there is a suspicion of a different but similar, or similar and co-morbid, disorder.
There have been some EEG abnormalities studied, yes, but there haven't been enough of these kinds of studies done worldwide for any method to be considered scientifically reliable. There have been multiple studies done with fMRIs on how abnormal growth in certain brain areas might cause changes in brain function. There are serotonin studies. All of this is preliminary. It's not even been resolved by the scientific community whether they think Asperger's is the same or different than HFA. It's been reported on television and in magazines that certain images or studies might hold a promise of diagnosis because the public is very interested in the possibility, but that also means that if there were a reliable test yet, it would be given.
You might be thinking of a study like 'Abnormal Attention in Autism Shown by Steady-State Visual Evoked Potentials' by Matthew Belmonte, where they looked at what happened to autistic brains during different shiftings of attention. A link to that study and many, many others can be found at the neurodiversity website.
There's so much information available about methods of evaluation and diagnosis it might be more efficient to send in an "ask an expert" query over at the Autism Today site, and ask a professional what might be a good way to dispute or confirm your specific situation.