parietal deficits may require a non-genetic trigger, as they were absent in siblings who ultimately remained healthy. This apparent ‘plastic’ response (inhibition of cortical thinning) in healthy siblings is intriguing and warrants replication. Within the healthy sibling group, regional cortical thickness at baseline was correlated with subsequent increases in overall ‘life functioning’ as measured by the Global Assessment Scale (GAS). This suggests a direct relationship between cortical thickness and a restitutive normalization process with general competence (GAS scores). In other words, better social and cognitive “competence” was predicted by initial cortical thickness. Whether this relationship between GM thickness and GAS reflects a causal effect of structure on function, or whether both have a common antecedent, remains unknown (Gogtay, Greenstein et al., 2007).
