EEG, or Electroencephalography, records electrical activity in the brain, using an array of electrodes attached to the scalp. Voltage fluctuations resulting from ionic current flows within the neurons of the brain can be detected, giving the physician a picture of any abnormal or substandard activity. The EEG test, usually lasts some 30-40 minutes, and has been used to identify epilepsy and is also used as a front line diagnosis for brain damage after a stroke or brain tumor.
Researchers at Harvard Medical School, compared EEG measurements of nearly 1000 children. Their test subjects were both with and without a previous history of autism. They used an array of 24 electrodes on the scalp, while the children were awake and alert. They then adjusted the results to account for any activity such as blinking, head movement of if the children became drowsy.
Autistic children generally have a reduced faculty of communication, including language and social skills. This tends to lead them to exhibit what could be characterized as anti social or abnormal behavior or attitudes, including rigidity of interests, or repetitive, ritualistic behavior. Researchers have tried using the MRI scanner to study the brain of patients afflicted with autism, but have not had solid results.
In general, autistic children seem to show poor short range connectivity in the left hemisphere of the brain, which is responsible for language, while at the same time having an increased connectivity in regions that are further apart from each other, indicating some compensation or misbalance is occurring. The EEG tests have proved more accurate - providing a clearer picture and are able to identify these patterns.
Dr Frank Duffy and Dr Heidelise Als who performed this research at the Boston Children's Hospital explained:
"EEG coherence is used to assess functional connectivity within the brain. Across all the age groups we tested, a set of 40 coherence measurements reliably and consistently distinguished between children with ASD and their controls."
The differences in brain connectivity were marked in children with autism, with much shorter distances needed between the electrodes, and this anomaly was especially apparent in the left area of the brain. Over long distances, the coherence increased, confirming the compensatory mechanism that scientists have believed existed for quite some time.
Beyond simply providing a confirmation of a theory, the test can be used in the future to better diagnose children with autism, or even be used to check infants who may not yet have any noticeable symptoms. This can help parents to adjust for the future and provide the child with more coping strategies. In the future, if drugs become available, it may also help implement treatment earlier in the development of the child.
Written by Rupert Shepherd