Hemoglobin status associated with performance IQ but not verbal IQ in Chinese preschool children

Abstract

Background Despite the body of literature that links anemia with poorer cognition in children and the evidence that the severity of the effects of anemia on children’s cognition vary in different populations, few studies have investigated the effects of anemia on the cognitive development of Chinese children. Study Design This longitudinal cohort includes 171 children from a developing region of China. Hemoglobin and iron levels were taken when the children were 4 years old. At age 6, the children’s cognition was tested with Chinese WPPSI. Psychosocial information was also used in analyses. Results Results showed that the children who had low Hb levels had significantly lower scores in PIQ, but not VIQ. Although blood Fe levels were not shown to moderate the link between hemoglobin levels and IQ, we found children who performed the best on IQ tests exhibited low iron levels concurrent with high hemoglobin levels, whereas the group who performed the worst exhibited high iron but low hemoglobin levels. We also found that psychosocial adversity did not differ significantly between children who had normal or low hemoglobin levels, although the effect of hemoglobin on PIQ became only suggestive after controlling for psychosocial adversity, therefore the relationship is not causal but only a suggestive association. Conclusion Our findings are in agreement with literature on the negative effects of anemia on children’s cognition and point to the possibility that the portions of the brain associated with PIQ components are particularly affected by low Hb during crucial periods of development.

The association of early linear growth and haemoglobin concentration with later cognitive, motor, and social–emotional development at preschool age in Ghana

“…These studies have focused on cognitive scores or educational achievement, with only one assessing motor (Kuklina et al, 2006) and none assessing social-emotional development. Although several studies have examined relationships of Hb concentration during early life with long-term developmental outcomes (Ai, Zhao, Zhou, Ma, & Liu, 2012;Aubuchon-Endsley et al, 2011;Aubuchon-Endsley et al, 2013;Eilander et al, 2010;Grantham-Mcgregor & Ani, 2001;Jianghong, Adrian, Venables, & Mednick, 2004;Olney et al, 2009;Su et al, 2016), only one study to our knowledge reported independent associations with Hb during specific periods of childhood by adjusting for Hb at other time points (Aubuchon-Endsley et al, 2013).…”

Effects of increased hemoglobin on child growth, development, and disease: a systematic review and meta‐analysis

“…Ai et al . found a significant correlation between Hb concentration at 48 months and verbal IQ ( r = 0.14, P < 0.05) and performance IQ ( r = 0.08, P < 0.05) at 72 months of age in Chinese children . In Icelandic children with 7.2% anemia prevalence, a significant association was reported between Hb at 12 months and expressive language development at 72 months of age …”

“…Many studies did not report the participation rate; of those that did, five studies reported a participation rate above 80% and three reported a participation rate between 60% and 80% . In only two studies was it unclear how the subsample of participants was selected . Some longitudinal studies had a loss to follow‐up above 20% .…”

“…In only two studies was it unclear how the subsample of participants was selected . Some longitudinal studies had a loss to follow‐up above 20% . The majority of studies excluded children with missing data, did not blind assessors to exposure status, and did not adjust correlation estimates for confounding variables.…”

Serum ferritin, serum nitric oxide, and cognitive function in pediatric thalassemia major

“…In accordance with this theory, a longitudinal cohort study by Ai et al in 171 children in China showed that children with low hemoglobin levels had a lower performance IQ, but normal verbal IQ. 17 Nitric oxide controls the transmission of information and plays a role in cognitive function, such as in learning and memory, so that NO deficiency may cause cognitive impairment. We found no correlation between verbal IQ or full scale IQ and serum NO levels.…”