Longitudinal evaluation of externalizing and internalizing behavior problems following iron deficiency in infancy.

OBJECTIVE This study examined externalizing and internalizing behavior problem trajectories as a function of both iron status in infancy and infant characteristics. METHODS A sample of 185 healthy Costa Rican children who either had chronic, severe iron deficiency or good iron status in infancy were followed for 19 years. RESULTS Mother ratings of externalizing and internalizing problems from age 5 to 11-14 years were higher for the chronic iron deficiency group compared with those with the good iron status. Iron deficiency in infancy predicted persisting externalizing problems over this time period, especially for those with low physical activity in infancy. Beyond adolescence, youth in the chronic iron deficiency group did not report more problems than those in the good iron group. CONCLUSIONS These findings underscore the importance of considering infant iron status along with early behavioral characteristics to better identify those children at greatest risk for persisting long-term behavior problems.