Aberrant Development of Social Cognition Network during Adolescence in Autism Spectrum Disorders

Abstract

Neither GM (ASD: 0.66±0.0 liters; Control 0.65±0.06 liters; Z=-0.18, P=0.78) nor WM (ASD: 0.41±0.04 liters; Control 0.43±0.04 liters; Z =-0.18, P =1.62) volume showed global differences between groups. The total intracranial volume of the ASD subjects (1.07±0.07 liters) was similar to that of the controls (1.08±0.09 liters) (Z =-0.67, P = 0.65). The gray-white absolute volume ratio was 1.60 for ASD and 1.53 for controls respectively. Regional Gray Matter Volume Difference Between Two Groups The exploratory analysis revealed individuals with ASD exhibited smaller GM volume in the right inferior frontal gyrus, precentral gyrus, postcentral gyrus, cuneus, right superior temporal gyrus and lingual gyrus. The regions that exhibited larger volumes in ASD were the cerebellum, paracentral lobule, superior parietal lobule, medial prefrontal gyrus, fusiform gyrus, middle frontal gyrus and subcallosal gyrus. Interaction of Age by Groups The right inferior parietal lobule and posterior cingulate of the adolescents with ASD showed a negative correlation with age whereas the controls displayed the opposite pattern. For the right inferior parietal lobule, the GM content with age had a significantly positive correlation in the control (r = 0.652, P = 0.001) but a negative correlation in the ASD (r = -0.434, P = 0.034). Additionally, the posterior cingulate had a significant interaction (controls: r = 0.672, P = 0.001; ASD: r = 0.021, P = 0.921). Conclusions In terms of global comparison, the present findings pointed out that the brain enlargement early in ASD childhood did not persist into adolescence. Regionally, imbalance GM volumes of participants with ASD appear in line with previous reports [6-7]. Notably, the right inferior parietal lobule and posterior cingulate showed a significant interaction of age throughout adolescence by groups as indicated by an accelerated age-related loss of GM volume in ASD whilst an age-related gain in control. We also found that the medial prefrontal cortex had a larger volume while the lingual cortex had a smaller volume, was in line with previous reports that described the frontal lobe as having the greatest enlargements and the occipital lobes having the least [8]. This may suggest that the cortical areas affected most in ASD are phylogenetically and ontogenetically late-developing regions that are essential to complex human cognitive functions such as executive function and social interaction. The current MRI study with the use of voxel-based morphometry provide evidence on the presence of aberrant development in the social cognition network, including inferior parietal lobule and posterior cingulate, during adolescence in ASD. These findings may lend indirect supports to the social brain hypothesis of autism.