9While advanced paternal age (APA) has repeatedly been associated with higher risk 10 for neuropsychiatric disorders, its effects on cognitive processes such as reading 11 have received minimal attention. Therefore, we examined the relationship between 12 APA, offspring's reading abilities, and brain measures in a longitudinal 13 neuroimaging study following 51 children from kindergarten through third grade. 14 APA significantly predicted reduced reading performance, independent of parental 15 reading history, socioeconomic status, home literacy environment, and birth order. 16This effect was mediated by gray matter volume change in the left posterior 17 thalamus, predominantly the pulvinar nuclei. Complementary analyses using 18 diffusion imaging data, Neurosynth, and 1000 Functional Connectome data 19 indicated the APA-related cluster links to the dorsal attention network. These 20 findings provide novel insights into the neurocognitive mechanisms underlying APA 21 effect on reading during its earliest phase of reading acquisition and suggest future 22 avenues of research on APA-related factors, such as de novo mutation, in reading. 23