Multiple Biomarkers of Maternal Iron Predict Infant Cognitive Outcomes

Biomarkers of Brain Dysfunction in Perinatal Iron Deficiency

Iron deficiency in the fetal and neonatal period (perinatal iron deficiency) bodes poorly for neurodevelopment. Given its common occurrence and the negative impact on brain development, a screening and treatment strategy that is focused on optimizing brain development in perinatal iron deficiency is necessary. Pediatric societies currently recommend a universal iron supplementation strategy for full-term and preterm infants that does not consider individual variation in body iron status and thus could lead to undertreatment or overtreatment. Moreover, the focus is on hematological normalcy and not optimal brain development. Several serum iron indices and hematological parameters in the perinatal period are associated with a risk of abnormal neurodevelopment, suggesting their potential use as biomarkers for screening and monitoring treatment in infants at risk for perinatal iron deficiency. A biomarker-based screening and treatment strategy that is focused on optimizing brain development will likely improve outcomes in perinatal iron deficiency.

Mediating and Moderating Effects of Iron Homeostasis Alterations on Fetal Alcohol-Related Growth and Neurobehavioral Deficits

We have previously demonstrated prenatal alcohol exposure (PAE)-related alterations in maternal and infant iron homeostasis. Given that early iron deficiency and PAE both lead to growth restriction and deficits in recognition memory and processing speed, we hypothesized that PAE-related iron homeostasis alterations may mediate and/or moderate effects of PAE on growth and neurobehavior. We examined this hypothesis in a prenatally recruited, prospective longitudinal birth cohort [87 mother-infant pairs with heavy prenatal alcohol exposure (mean = 7.2 drinks/occasion on 1.4 days/week); 71 controls], with serial growth measures and infant neurobehavioral assessments. PAE was related to growth restriction at 2 weeks and 5 years, and, in infancy, poorer visual recognition memory, slower processing speed, lower complexity of symbolic play, and higher emotionality and shyness on a parental report temperament scale. Lower maternal hemoglobin-to-log(ferritin) ratio, which we have shown to be associated with PAE, appeared to exacerbate PAE-related 2-week head circumference reductions, and elevated maternal ferritin, which we have shown to be associated with PAE, appeared to exacerbate PAE-related visual recognition memory deficits. In causal inference analyses, PAE-related elevations in maternal ferritin and hemoglobin:log(ferritin) appeared to statistically mediate 22.6-82.3% of PAE-related growth restriction. These findings support potential mechanistic roles of iron homeostasis alterations in fetal alcohol spectrum disorders (FASD).

Heart rate-defined sustained attention in infants at risk for autism

Background

Although aberrant visual attention has been identified in infants at high familial risk for autism, the developmental emergence of atypical attention remains unclear. Integrating biological measures of attention into prospective high-risk infant studies may inform more nuanced developmental trajectories, clarifying the onset and course of atypical attention and potentially advancing early screening or treatment protocols. Heart rate-defined sustained attention (HRDSA) is a well-validated biological measure of attentional engagement that, in non-clinical infant populations, provides incremental information about attentional engagement beyond looking behaviors alone. The present study aimed to examine the characteristics and clinical correlates of HRDSA in high-risk infants, informing whether HRDSA may operate as a promising biological measure of attention and clinical symptoms in this population.

Methods

We examined age-related patterns of HRDSA during a passive looking task in 5- to 14-month-old high-risk infant siblings of children with autism (n = 21) compared to low-risk controls (n = 21), with most participants contributing multiple assessments. Emergent autism features were measured using the Autism Diagnostic Observation Schedule at 24 months. Primary dependent variables included the proportion of time in behavioral attention, proportion of time in HRDSA, and average heart rate deceleration during HRDSA. For each variable, we used nested multilevel models to examine whether attention differed by group, as well as whether attention predicted emergent autism features among high-risk infant siblings.

Results

As expected, HRDSA served as a global biological measure of attention in high-risk infants, predicting greater variability in group risk status than behavioral looking alone. Among high-risk infants, more severe ASD features were also associated with increasingly shallow heart rate deceleration during HRDSA across development, suggesting abnormal qualities of HRDSA may inform individual differences within this population.

Conclusions

These preliminary findings provide initial evidence that HRDSA may offer a sensitive, affordable, and portable biological measure of attention that may enhance understanding of atypical attention in high-risk infants. Using this method, we also provide initial evidence that atypical patterns of heart activity previously reported in children and adults with autism may emerge in the first year of life, warranting further study of how HRDSA may specifically inform attention profiles in ASD.