Researchers from the University of Alabama in Birmingham have identified a possible mechanism of human cognition in the background of autism spectrum disorders or ASD.
Diagnosis for ASD is still based on behavior. Psychologists and medical experts with clinical expertise use autism diagnostic diagnosis and autism diagnostic interview to diagnose autism – these two tests are considered a gold standard.
However, setting the diagnosis may be a longer process due to several factors, including lack of resources and trained clinicians. Thus, the diagnosis of autism is delayed on average by the age of 5 or 6 years.
"Within ASD, two important research questions are: How can we reduce the delay in diagnosis and what sort of intervention can we give to a child?" said Dr. Rajesh Kana, associate professor of psychology at UAB College of Arts and Sciences. "Our results primarily correspond to the first question, but if research results can be repeated many times for external validation, they can also be used to find answers to this second question."
Using functional magnetic resonance imaging or fMRI, postdoctoral collaborator Omar Maximo and Kana reviewed 306 people aged 8 to 39, with 138 individuals in the ASD group and 168 in a typically developing group. They observed functional connectivity, which relates to the synchronization of activity in different regions of the brain, to two types of networks, unimodal and supramodal, in brain areas below the cerebral cortex. The subcortical areas contain structures that receive into and out of the cortex and sensory organs, and play a major role in cognitive and social functions.
"Think of the brain network as a system of interconnected highways leading you to cities – white matter connections lead you to different parts of the brain," Maximo said. "Unimodal areas are primarily involved in basic sensory processes, while supramodal areas – a collection of multiple brain areas – are responsible for multiple cognitive processes."
Maximo and Kana have discovered that there is excessive association between unimodal-subcortical links and underconnectivity in supramodonal-subcortical links to ASD individuals, compared to a typically developing control group, pointing to the link between ASD linkage and expression.
The study is unique in focus on subcortical parts of the brain. "We are trying to find a sign of autism and why people with ASD show some social and behavioral symptoms," Kana said. "As the structure and function of the brain is affected, it can help us understand why the patients with ASD are different."
Finding a biomarker for ASD, says Kana, can greatly assist early identification of individuals and initiate interventions, such as cognitive behavioral therapy or teaching of the required social skills, and ultimately improve connections between sensory and higher cognitive sensory processes.