During adolescence, many psychiatric disorder diagnoses (mood disorders, schizophrenia or obsessive-compulsive disorders) are made. However, the reasons for this vulnerability in adolescents remain poorly understood.

Recent brain imaging studies have shown that the brain continues to mature and develop past childhood and into the 20s and 30s. These changes – which are greater in some brain regions than in others, particularly those that house higher cognitive functions such as language or consciousness – are directly related to mental health development.

To learn more, Joliot researchers used data from an open-access developmental cohort (Healthy Brain Network, HBN) to analyze associations between cortical surface markers and irritability and anxiety scores as measured by parents and self-reports – irritability and anxiety being associated with an elevated risk of mood disorders in adulthood.

They isolated a sample of 718 subjects with good quality MRI data acquired as part of the HBN. Then, for each subject they measured the cortical thickness and surface area as well as the "local gyrification index", characterizing the formation of the characteristic folds of the cerebral cortex.

Next, these three brain maturation markers were compared with parental reports of irritability and anxiety in 658 youths with a mean age of 11.6 years.

• Irritability is associated with a decrease in the area of the bilateral prefrontal cortex and precuneus (an area at the back of our brain, on the medial surface of the parietal lobe of the cerebral cortex).
• Anxiety is associated with a decrease in the local gyrification index in the anterior cingulate cortex and the dorsomedial prefrontal cortex.

These results are consistent with current models of emotion regulation network maturation. They thus reveal anatomical changes in dysfunctional regions in children at risk for mood disorders.