Figure 2

Graph metrics of functional brain networks are related to memory performance in Aβ+ older adults. (A–C) We tested for group differences in graph metrics between Aβ+ and Aβ- older adults at each cost level using repeated measures ANCOVA analysis, controlling for age, sex, and education. There was no significant main effect of Aβ group or Aβ group by cost interaction, indicating no differences in graph metrics between the groups. Left side plots demonstrate the group mean and standard error at each cost, with Aβ+ group in red, and the Aβ- group in navy. The right hand plot shows a closer look at this comparison at one cost, indicated by the shading, at either the strongest cost or at the mean of costs. (D–F) We tested for an interaction between Aβ status and memory performance at each cost to determine if the relationship between memory and graph metrics differ by Aβ status. This was performed using repeated measures ANCOVAs at each cost, with the Aβ status by memory interaction being our outcome of interest. We performed follow-up linear regressions at each cost, with the t-statistic (diamond shape) of the interaction between Aβ status and memory being plotted on the left side. The t-statistic crossed the p < 0.05 significance threshold (dashed yellow line) and p-FDR significance threshold (< 0.0071, dotted green line) for the majority of costs. The gray shaded cost levels are plotted on the right side panel, showing the scatter plot of the interaction. Higher local efficiency (D), modularity (E), and small worldness (F) was significantly associated with better memory performance in the Aβ group (red) but not the Aβ− group (navy). *p < 0.05; **p < 0.01; ***p < 0.001.