The replicability of neuroimaging results has recently been brought into question (22, 23). The large sample size of the present study facilitated the adoption of an optimized split-half strategy to verify the reliability of effects. The data were split into two halves (a discovery data set and a replication data set) with statistically matched stratification for age, sex, and intracranial volume within each site and dependence status. Since each region of interest was analyzed separately, a false discovery rate method (the Benjamini-Hochberg procedure) was used to control for multiple comparisons on the first half of the data (the discovery data set). Associations discovered in the first half of the data are reported here as significant only if they were replicated in the second half of the data (the replication data set), that is, if the sign of the difference in means was the same and the null hypothesis had a probability <0.05.
