Systematic Review Found No Association Between Brain Structure and Fluid Intelligence in Individuals Born Very Preterm

AIM: Individuals born very preterm have specific deficits in the fluid domain of intelligence. We investigated whether changes in brain volume and diffusivity, measured using magnetic resonance imaging, were linked to these deficits.

METHOD: A systematic search in MEDLINE focused on studies published in English from 1 January 2000 to 11 April 2023. Studies of individuals born very preterm were eligible if data were available on both structural magnetic resonance imaging and intelligence tests or school achievements. These were screened and analysed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS: We identified 16 reports on 1576 individuals born very preterm and 754 born term. The age range was 4-30 years. Most local measures of grey matter were reduced in individuals born very preterm, except for volumes in the prefrontal cortex. General intelligence was positively associated with structural brain measures, except for white matter mean diffusivity and prefrontal cortical thickness in some studies. Similar positive associations were found between both crystallised and fluid intelligence and most structural brain measures.

CONCLUSION: The fluid domain did not show a specific brain signature related to volume or diffusivity. Brain network organisation may be more important for higher-order cognitive function.