We tested whether adolescents differ from each other in the structural development of the social brain, and whether individual differences in social brain development predicted variability in friendship quality development. Adolescents (N = 299, Mage T1 = 13.98 years) were followed across three bi-annual waves. We analysed self-reported friendship quality with the best friend at T1 and T3, and bilateral measures of surface area and cortical thickness of the medial prefrontal cortex (mPFC), posterior superior temporal sulcus (pSTS), temporo-parietal junction (TPJ), and precuneus across all waves. At the group level, growth curve models confirmed non-linear decreases of surface area and cortical thickness in social brain regions. We identified substantial individual differences in levels and change rates of social brain regions, especially for surface area of the mPFC, pSTS, and TPJ. Change rates of cortical thickness varied less between persons. Higher levels of mPFC surface area and cortical thickness predicted stronger increases in friendship quality over time. Moreover, faster cortical thinning of mPFC surface area predicted a stronger increase in friendship quality. Higher levels of TPJ cortical thickness predicted lower friendship quality. Together, our results indicate heterogeneity in social brain development and how this variability uniquely predicts friendship quality development.

structural brain development, social brain, adolescence, friendship quality, longitudinal
Data of the Braintime study has been financially supported by a starting grant from of the European Research Council (ERC-2010-StG-263234 awarded to E.A.C.), a grant from the Netherlands Organization for Scientific Research (NWO-VICI 453-14-001 awarded to E.A.C.) a grant from the Netherlands Organization for Scientific Research (NWO-VENI 451-10-021) awarded to B.G., and a grant from the Netherlands Organization for Scientific Research to the Consortium Individual Development (CID) (024.001.003).
dx.doi.org/10.1093/scan/nsaa166, hdl.handle.net/1765/132217
Social Cognitive and Affective Neuroscience (Online)

Becht, A.I, Wierenga, L.M, Mills, K.L, Meuwese, R, van Duijvenvoorde, A.C.K, Blakemore, S.-J, … Crone, E.A. (2020). Beyond the Average Brain: Individual Differences in Social Brain Development are Associated with Friendship Quality. Social Cognitive and Affective Neuroscience (Online). doi:10.1093/scan/nsaa166