Researchers at the CNRS, Aix-Marseille University and AP-HM have identified a brain marker specific to autism, detectable by MRI and present from the age of two. The anomaly lies in a shallower fold in Broca’s area, a region of the brain specialized in language and communication, altered functions in patients with autism.
This discovery is able to facilitate the early diagnosis and management of these patients. This was made possible thanks to the medical imaging processing skills of the Institute of Neurosciences of Timone (CNRS / Aix-Marseille University) and by access to a cohort of homogeneous patients, diagnosed very young and all having been Evaluated according to the same protocol at the Autism Resource Centre of Provence. The results of their collaboration were published on 12 January 2016 in the Biological Psychiatry journal : Cognitive Neurosciences and Neuroimaging. Autism spectrum disorders are a set of neurodevelopmental disorders (typical autism, Asperger's syndrome or invasive disorder of unspecified development) that primarily affect social relations and communication. They are associated with an abnormal development of the brain. Recent neuroimaging evidence suggests abnormalities in cerebral cortical folds (formation of convolutions on the brain surface). However, conventional neuroanatomy measures have so far failed to identify specific markers for each of these disorders, including typical autism.
Researchers of the Timone Institute of Neurosciences were interested in a new geometric marker, called "sulcal pit". It is the deepest point of each furrow of the cerebral cortex. It is from these points that the folds develop on the surface of the brain. They are therefore set up very early in development, probably under genetic influence, which makes them suitable for comparisons between individuals. On the basis of MRI results, the researchers observed sulcal pits in 102 young boys aged 2 to 10 years, classified into three groups (children with typical autism, children with unspecified invasive developmental disorder, Of autism spectrum disorders). By comparing the three groups, they found that in Broca’s area (a region known to be implicated in language and communication), the maximum depth of a furrow was smaller in children with autism by comparison To the other two groups. Interestingly (although counterintuitive), this very localized atrophy is correlated to communication performance in the autistic child group: the deeper the sulcal pit is, the more limited the skills are in terms of language production.
This abnormality specific to children with autism could therefore constitute a biomarker of the pathology that could help in earlier diagnosis and management, as early as at the age of two. Currently, autism is diagnosed on the basis of clinical signs only, through the observation of children and interviews with their parents, and diagnosis is made on average at 4 and a half years old in France. This study also resulted in a discovery about brain development. While people thought that cortical folding was completed at birth, researchers observed that some furrows (the most superficial) continue to widen with age, just as for children with autism and other children. Biomedical research can also shed light on understanding the mechanisms of living organisms.
