Biological Test for ADHD?

NewScientist.com is reporting that a biological test for ADHD (Attention Deficit Hyperactivity Disorder) has been developed.

The first biological test for attention-deficit hyperactivity disorder has been developed. The researchers claim the diagnosis, based on examination of eye movements, is more than 93% accurate and could lead to earlier identification and treatment for children with the condition.

Scientists analysed the eye movements of 65 children aged between four and six in Thessaloniki, Greece. About half of the children had been diagnosed as having ADHD through the standard method of psychological assessment and the use of questionnaires.

The children were placed in front of a computer screen while wearing special goggles to monitor their eye movements and asked to use their eyes to "lock-on to" and follow spots of light that traversed the screen during a 10-minute test.

"Children with ADHD show large difference in eye movements compared with normal children. For example, those without ADHD could follow the light spot for 30 seconds to as much as five minutes, whereas the children with the disorder could only follow the stimulus for about three to five seconds," says Giorgos Pavlidis at University of Brunel, UK, who led the study.
Perhaps this is a result of my medical naivete', but when I hear the term "biological test" I think of tests that are not open to subjective analysis - pregnancy tests, HIV tests, that sort of thing. So, I was a little deflated to read that this was not a diagnostic tool of that caliber.

I'm also skeptical of putting too much faith in the results this study when the sample is so small - sixty-five chidren - and so demographically homogenous. If doctors are going to use this tool as part of a battery of tests to arrive at diagnoses of ADHD, then I support that. However, Mr. Pavlidis seems to think that his test is all that's needed for a credible diagnosis.
"Children as young as three years old could benefit from the test. It could reliably identify those children who have ADHD early on so that effective intervention could be given to reduce loss of confidence and other behavioural and psychological problems," Pavlidis told New Scientist.
I should see if MedPundit has anything to say on this...