Longitudinal changes in resting state networks in early presymptomatic carriers of C9orf72 expansions

•Functional connectivity changes over 18 months in presymptomatic C9orf72 carriers.•Thalamic networks have reduced functional connectivity, but are stable over time.•Presymptomatic FC patterns trend toward those of symptomatic C9orf72 carriers.•Reduced connectivity of posterior parietal regions occurs in different networks.