Low serum ferritin associated with attention impairment in adolescents

Low serum ferritin concentrations are associated with impairment in sustained attention among adolescents 16–19 years of age in Hong Kong, researchers from the Chinese University of Hong Kong (CUHK) have reported.

 

In a previous study, the researchers found iron deficiency (ID; serum ferritin concentration <15 µg/L) in 11.1 percent of adolescents 16–19 years of age in Hong Kong. The study involved 523 participants (female, 65 percent) recruited through Hong Kong Red Cross blood donation campaigns at 16 secondary schools between October 2020 and December 2021. ID was found in 17.1 percent of the girls, but not in boys, while ID anaemia (IDA) was found in 10.9 percent of the girls. [Int J Environ Res Public Health 2023;20:2578]

 

The present study evaluated associations between iron status and attention outcomes in the domains of sustained attention, inattention, and impulsivity among the participants. [Hong Kong Med J 2025;do:10.12809/hkmj2310950]

 

About half (47.6 percent) of the participants demonstrated normal function in all three attention domains, while approximately one-quarter had moderate-to-severe impairment in sustained attention (25.0 percent), inattention (27.7 percent), or impulsivity (30.0 percent).

 

Among female participants, respective rates of moderate-to-severe impairment in the three attention domains were 36.2, 27.6 and 37.9 percent in those with ID, and 26.0, 43.5 and 43.4 percent in those with IDA. In male participants, rates of moderate-to-severe impairment in these attention domains were 18.0, 23.5 and 22.4 percent, respectively.

 

In the overall cohort, participants with impairment in sustained attention had significantly lower median serum ferritin concentrations than those with intact attention function (51.2 vs 73.9 µg/L; p=0.020).

 

Lower serum ferritin concentration was significantly associated with impairment in sustained attention (risk ratio [RR], 0.825; 95 percent confidence interval [CI], 0.732–0.946; p=0.040) after adjustment for age and sex. “Each 10 µg/L increase in serum ferritin concentration was associated with a 17.6 percent decrease in risk of sustained attention impairment,” the investigators noted.

 

In female participants, median serum ferritin concentrations were significantly lower in those with impairment in sustained attention than those with intact attention function (40.0 vs 48.5 µg/L; p=0.038). Multivariable analysis showed a similar association that was not statistically significant (RR, 0.954; 95 percent CI, 0.904–1.005; p=0.073).

 

Among male participants, iron reserves were not significantly associated with attention outcomes.

 

The study also showed an association between higher level of fatigue and impairment in sustained attention (RR, 0.772; 95 percent CI, 0.652–0.926; p=0.004), inattention (RR, 0.824; 95 percent CI, 0.733–0.942; p=0.016), and impulsivity (RR, 0.792; 95 percent CI, 0.683–0.922; p=0.004).

 

“Our findings highlight the importance of timely ID screening and correction in adolescents, particularly among females,” the investigators concluded.

 

“Adolescents with low iron reserves should receive counselling on consumption of iron-rich food and iron supplementation to alleviate fatigue,” they suggested. “ID correction in adolescents could reduce fatigue levels, which may indirectly improve attention outcomes.”

 

“ID prevention in adolescents requires effective management of knowledge gaps related to food nutrition, dieting, and body image. It is important to develop nutrition education programmes to encourage proactive adoption of dietary and other nutrition-related behaviours that promote health and well-being,” said principal investigator, Professor Chi-Kong Li of CUHK’s Department of Paediatrics.