Impact of iron deficiency on attention among school-aged adolescents in Hong Kong

Adolescence is a critical period for higher-order cognitive function development. The adverse effects of low iron reserves on attention are particularly relevant to school-aged students. Based on our previous study identifying a 11.1% prevalence of iron deficiency (ID) among Chinese school-aged adolescents aged 16 to 19 years in Hong Kong, the present study examined the association between iron status and attention outcomes in these adolescents.

This cross-sectional study recruited 523 adolescents (65.0% female; mean age=17.5 years) from 16 local schools. Serum ferritin levels and complete blood counts were measured. Iron deficiency was defined as serum ferritin concentration <15 μg/L. The Conners Continuous Performance Test Third Edition was administered to assess impairments in three attention domains, namely, sustained attention, inattention, and impulsivity. Multivariable analyses, conducted both for the overall cohort and stratified by sex, were used to evaluate the associations between serum ferritin levels and attention outcomes, adjusting for fatigue and dietary patterns.

In the overall cohort, a lower serum ferritin concentration was significantly associated with sustained attention impairment (risk ratio [RR]=0.825, 95% confidence interval [95% CI]=0.732-0.946; P=0.040). Among female participants, those with sustained attention impairment had significantly lower serum ferritin concentrations than those with intact attention function (median=40.0 μg/L; interquartile range [IQR]=18.8-52.1 vs median=48.5 μg/L; IQR=21.8-73.8; P=0.038). Multivariable analysis showed a similar trend, though the association was not statistically significant (RR=0.954, 95% CI=0.904-1.005; P=0.073). Among male adolescents, iron reserves were not significantly associated with attention outcomes.

These findings highlight the importance of timely ID screening and correction in school-aged adolescents, particularly among female adolescents.