Children born before the U.S.-mandated folic acid fortification of foods had atypical cortical maturation and greater psychosis risk compared with children born afterwards.

In 1996, the U.S. mandated fortification of wheat flour with folic acid to avoid spina bifida. This clear demarcation was the foundation for an analysis of cortical maturation and psychopathology risk based on three MRI studies in children aged 8 to 18 years, who were born in a period ranging from before fortification to afterwards.

The first study (MGH) involved 292 children with clinical reasons for scanning (e.g., epilepsy) but normative results; scans occurred before, during, or after the mandate. The group born after folic acid fortification had greater cortical thickness of frontal and temporal areas and delayed thinning in temporal and parietal regions, compared with the group born prefortification. The transition-year group (1997) had intermediate findings.

The prefortification group had higher risk for psychosis spectrum psychopathology than the postfortification group.