This autism marker can be seen on MRI and is present from two years of age.
It’s in the Broca’s area or language expression headquarters of the brain.
Scientists at CNRS, Aix-Marseille Université, and AP-HM have made this discovery.
The marker shows up as a less deep fold in Broca’s area, a part of the brain important for language and communication.
Some autistic people have difficulty with talking, and this difficulty comes in varying degrees.
For instance, in some, speech is completely absent, though a single word might just come out on rare occasions.
For others, speech is possible but only within the confines of structure.
For example, an autistic adult may not be capable of conversation or talking about what they did earlier that day other than with a few words, such as “the mall,” when asked.
But put a random pamphlet before them and they’ll be able to fluently read the text out loud.
And of course, many autistic individuals are chatterboxes.
The Broca’s finding could help diagnose and manage autism earlier.
It was made possible thanks to the imaging expertise at the Institut de Neurosciences de la Timone and a group of very young patients all assessed with the same protocol at the Centre de Ressources Autisme PACA.
The imaging studies suggest abnormal cortical folding, or unusual brain surface patterns.
But until now, standard methods had not found markers specific to autism.
This New Approach
The researchers focused on a new geometric marker called the sulcal pit.
Sulcal pits are the deepest points in the folds of the brain’s surface.
They appear very early in development, probably influenced by genetics.
Because of this, they are useful for comparing brain structure between individuals.
The scientists looked at MRIs of 102 boys from two to 10.
They were divided into three groups: autism, pervasive developmental disorder not otherwise specified, and typically developing.
They compared the sulcal pits in Broca’s area and found that the autistic subjects had shallower pits than did the other two groups.
The shallowness was linked to social communication skills: The shallower the pit, the more impaired the child’s language production.
Based on this, one can assume that in autistic people who don’t have difficulty with expressive language, the sulcal pits in their Broca’s area would appear normal or typical.
The study did not look at this angle. In other words, a shallow pit may strongly indicate autism, but this wouldn’t necessarily mean that a normal pit can exclude autism, either. Some autistic people hit speech milestones at a normal time frame (Asperger’s syndrome, which in 2013 became grouped under the umbrella of Autism Spectrum Disorders as Level 1 ASD).
A Potential Biomarker
Nevertheless, a shallow sulcal pit may serve as a biomarker for autism in some cases.
Currently, autism is diagnosed based on clinical observation and, when possible, parent interviews.
In adults the assessment also involves self reporting of life experiences.
The study also showed that some cortical folds continue to deepen after birth.
This happens in the same way in both autistic and typically developing children.
This finding suggests that cortical folding is not fully complete at birth.
The study was published January 2016 in Biological Psychiatry: Cognitive Neurosciences and Neuroimaging.
