University of Utah and Harvard researchers have developed a brain scan test that is able to detect individuals with high functioning autism with 94 per cent accuracy: they hope their method, which uses MRI to measure deviations in circuitry in key parts of the brain, will lead to a test based on biomarkers to replace the current subjective methods for diagnosing autism, as well as improve our understanding of autism and its treatment.
The lead author of the study was Dr Nicholas Lange, Associate Professor of Psychiatry at Harvard Medical School and director of the Neurostatistics Laboratory at Harvard-affiliated McLean Hospital, both in Boston, Massachusetts. The senior author was Dr Janet Lainhart, Principal Investigator of the research at the University of Utah.
Lange, Lainhart and colleagues, also from Harvard and the University of Utah, plus other research centers, wrote about their findings in a paper published online on 2 December in the journal Autism Research.
In their background information the authors explained they had wondered if using imaging techniques to study parts of the brain that are central to language, emotion and social cognition, they might find some potential physical biomarkers that would be sufficiently robust to be of clinical value in the diagnosis of autism.
They proposed to study the white matter microstructure (WMM) of the temporal gyrus (STG) and temporal stem (TS): two regions of the temporal lobe that contain the relevant circuitry.
For the study, they recruited two groups of participants: one group was 30 boys and men diagnosed with high functioning autism aged between 7 to 28 years, and the other group was 30 matched normally developing individuals (the controls).
The autism group had been diagnosed using the standard subjective scoring system, which assesses patients and also asks their parents about their behavior and functioning in many areas of day to day life, including language and social interaction.
The researchers wrote that they also examined “language functioning, adaptive functioning, and psychotropic medication usage”.
All the participants then underwent brain scans that used an MRI technique called Diffusion Tensor Imaging (DTI) to measure various aspects of the white matter microstructure of their STG and TS brain regions. DTI senses how easy it is for water to diffuse along the axons in the microstructure of the brain.
They found six distinct characteristics, which taken together made the “Lange-Lainhart test” highly able to “discriminate individuals with autism from individuals without autism with 94% sensitivity, 90% specificity, and 92% accuracy,” they wrote.
They also replicated the result in a second sample of 12 males with autism and 7 matched controls who had taken part in a previous DTI study.
Here is how the researchers described two of the characteristics:
“In the STG, we find reversed hemispheric asymmetry of two separable measures of directional diffusion coherence, tensor skewness, and fractional anisotropy. In autism, tensor skewness is greater on the right and fractional anisotropy is decreased on the left.”
Lainhart told the press that:
“The differences picked up on the study correlate with clinical symptoms that are part of the features of autism.”
“There is less directional flow to and from brain regions where there should be more information exchange,” added Lange.
They said their test is not yet ready for clinical use, but these are the most promising findings so far.
“Indeed, we have new ways to discover more about the biological basis of autism and how to improve the lives of individuals with the disorder,” said Lainhart.
The team are planning to study and develop the test further, and hope to release findings in a year or two.
They want to include patients who are severely autistic, younger children, and also non-autistic people with brain disorders such as developmental language disorders, ADHD and OCD.
If further research supports these findings, the researchers hope their test will someday replace the current subjective methods of diagosing autism, which are not based on biological measurement.
They think it might also be used to study the development of autism:
“We can gain a better understanding of how this disorder arises and changes over the lifetime of an individual, and derive more effective treatments,” said Lainhart.
“Atypical diffusion tensor hemispheric asymmetry in autism.”
Nicholas Lange, Molly B. DuBray, Jee Eun Lee, Michael P. Froimowitz, Alyson Froehlich, Nagesh Adluru, Brad Wright, Caitlin Ravichandran, P. Thomas Fletcher, Erin D. Bigler, Andrew L. Alexander and Janet E. Lainhart.
DOI: 10.1002/aur.162
Additional source: McLean Hospital.
Written by: Catharine Paddock, PhD