Fig. 4.

Overlap between genetic organization of cortical thickness and developmental and aging-related change. (A) The cortex was parcellated into 12 regions (clusters) of maximal shared genetic influence, based on an independent sample of 406 middle aged twins (4). The fuzzy clusters as shown were thresholded at 0.5. (B) (Center) Genetic correlations between the clusters. The genetic correlation matrix was compared with the correlations matrices for representing the relationships between cortical thickness change in the same clusters in development (<20 y; Left) and aging (≥20 y; Right). The Louvain algorithm was run to find the optimal community structure in each correlation matrix separately, illustrated by the black lines within the color charts, and the development and genetic clusters were ordered according to this algorithm. For aging, the Louvain algorithm suggested a slightly different organization (SI Text), and to allow comparisons with the two matrices, the same cluster ordering is used, without the community structure shown. (C) Thickness in each genetically defined cluster was demeaned and fitted to age by use of GAMM and plotted together with the mean of all clusters for comparison purposes. The width of the fit line represents the 95% CI. The y axes are optimized for the data range for each cluster. The blue lines represent the demeaned trajectory for each cluster, whereas the red lines represent the mean of all clusters.