Influence of intermittent iron and folic acid supplementation on cognitive abilities among adolescent girls in northwestern Tanzania

Iron and folic acid (IFA) supplementation to reduce anemia is key for improving substantial lost disability adjusted life years (DALYs) for adolescent girls. This study assessed the impact of weekly IFA supplementation (WIFAS) on cognitive ability among adolescent girls in the Simiyu Region in northernwestern Tanzania. This cross-sectional comparative evaluation study of 770 adolescent girls (396 –WIFAS supplemented; 374 –not supplemented) evaluated the association between WIFAS and cognitive ability through a face-to-face survey and cognitive ability assessment using standardized tests (Span-forward Test, Span-backward Test and Maze Test). Using a modified Poisson regression, we controlled for the geographic setting (urban vs rural), availability of potable water and feeding programs in schools, age and school level of adolescent girls, parental status, main parental economic activities, and the number of teachers. Participants were between the ages of 11 and 19 years, with more than half (57%) between 12–15 years of age. Those with WIFAS had higher cognitive ability (Span-forward scores, χ(2) = 46.34% p <0.001; Span-forward, χ(2) = 46.34% p <0.001; and Global Composite Cognitive Performance (GCCP), χ(2) = 32.52% p<0.001). Among the IFA supplemented adolescent girls, secondary school level had a significantly higher score with respect to Span-backward (aPR = 1.43, 95% CI = 1.06–1.62); Span-forward ability (aPR = 1.26, 95% CI = 1.04–1.53) and Maze Test ability (aPR = 1.12, 95% CI = 1.01–1.25) as compared to their counterpart in primary school level. Individual adolescent girls with WIFAS and living with both parents performed much better on the Span-backward Test (aPR = 1.22, 95% CI = 1.07–1.68) as compared to those living with relatives and/or orphans. The presence of potable water program among the WIFAS schools resulted in a higher Span-backward ability (aPR = 1.34, 95% CI = 1.03–1.89); and GCCP (aPR = 1.27, 95% CI = 1.03–1.75). Adolescent girls from WIFAS schools with feeding program had higher Span-forward (aPR = 1.38, 95% CI = 1.03–1.63) ability as well as a higher Maze Test (aPR = 1.15, 95% CI = 1.07–1.26) score. The present study provides compelling evidence that WIFAS is positively associated with higher cognitive ability among adolescent girls. Nevertheless, IFA interventions are still rare in communities across Tanzania.