The Mediating Role of Processing Speed in Reading-Related White Matter Tracts and Word Reading Skills of Adult Survivors of Childhood Brain Tumor

The purpose of this study was to investigate the relationship between word reading and white matter (WM) integrity in the reading system and test a theory-based moderated mediation model such that relationship of WM integrity with word reading is mediated by processing speed and indirect effect is moderated by group. Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (mean age=24.19(4.51) years, 62% female). Tractography identified the WM tract for three reading system connections. Fractional anisotropy of the IFOF and PT-OT tracts were significantly correlated with word reading in survivors (r=.55, .46, respectively; p<.05) and controls (r=.59, p<.01 IFOF). The moderated mediation model was significant for IFOF and PT-OT, such that the indirect effect of processing speed was only present for survivors (CI: 2.88, 28.33). Results suggest the occipitotemporal area is a critical component of the reading system in adults. Results align with the developmental cascade model. INDEX WORDS: DTI, White matter, Reading, Childhood brain tumor survivors, Long term, Processing speed THE MEDIATING ROLE OF PROCESSING SPEED IN READING-RELATED WHITE MATTER TRACTS AND WORD READING SKILLS OF ADULT SURVIVORS OF CHILDHOOD BRAIN TUMOR