Neural and behavioural correlates of theory of mind reasoning in five-year-old children born preterm

Behavioural studies suggest atypical or delayed development of "theory of mind" (ToM; our ability to reason about others' mental states) following preterm birth. Using pre-registered analyses of behavioural and movie-viewing functional magnetic resonance imaging (fMRI) metrics of ToM, we tested for a domain-specific impact of preterm birth (24-32 weeks' gestational age) on theory of mind development at age 5 years. Preterm-born children (n = 52) scored lower than term-born comparators (n = 58) on a linguistic behavioural ToM task, but this difference was primarily driven by differences in receptive language. Neurally, preterm-born children (n = 30) had qualitatively similar responses in brain regions that support ToM reasoning to a short movie to term-born comparators (n = 46), as characterised by four neural metrics; responses to one scene differed as a function of gestational age. Using intersubject correlation analyses, we found that preterm-born children's ToM network responses were more heterogenous than term-born children's responses; however, individual preterm-born children's responses most resembled those observed in same-age term-born children, relative to younger children or other preterm-born children. Taken together, preterm birth does not appear to preclude broadly similar functional development in ToM brain regions by age 5 years.