Spontaneous motor activity in human infants with iron-deficiency anemia
Introduction
There is ample reason to suspect that iron-deficiency might alter spontaneous motor activity in infants. In rodents, iron-deficiency anemia (IDA) has been reported to reduce overall activity [1] and to alter the organization of its circadian pattern, including a total reversal [2], [3]. One study that systematically varied the timing of iron-deficiency during early development also found that iron-deficient rats moved less in a home-orienting task [4]. In the single study of motor activity in the iron-deficient primate—a small pilot project involving juvenile monkeys, even mild iron-deficiency anemia dramatically decreased running and playing [5]. In the adult human, iron-deficiency anemia and, in some cases, iron-deficiency without anemia reduce maximal physical performance, submaximal endurance, and work productivity (see reviews [6], [7], [8], [9], [10]). In school-aged children, the few published studies of iron-deficiency and motor activity report decreased activity [11], [12], [13]. Thus, evidence from animal models and studies of human children and adults indicates that iron-deficiency alters motor activity.
However, there is little information on this question in the iron-deficient human infant. The lack of research is striking, especially since infants and toddlers are among the groups at highest risk for iron-deficiency. Furthermore, in infancy, physical activity plays additional important roles in learning from the environment and in cognitive development [14]. To date, the only observations of activity in iron-deficient anemic infants are contained in a study of play behavior and mother–infant interaction. Using crude measures of activity (crossing gridlines in a playroom, moving beyond arm's length from the mother, etc.), the study's results suggested decreased activity [15].
The purpose of the present study was to assess the levels of spontaneous motor activity in infants with and without IDA. This pilot study was conducted in Chile and applied advanced methods of measuring activity in a controlled but ecologically valid situation–activity immediately before and after an afternoon nap. We hypothesized that IDA infants would demonstrate lower levels of motor activity compared to control infants.
Infant health is generally excellent in Chile, but iron-deficiency on a dietary basis has been common. Previous studies show that 27–35% of Chilean infants, including those solely breast fed, develop iron-deficiency anemia at 9–18 months of age, and biochemical evidence of iron-deficiency is present in 43–65% [17], [18]. Routine pediatric care and infant feeding practices in Chile during this study did not include iron supplementation.
Section snippets
Subjects
The activity study was conducted in Chile between 1991 and 1996 in conjunction with the neurophysiological components of a larger study [16] on the behavioral and neuromaturational effects of iron-deficiency anemia in infancy. Infant activity could be measured in only a subset of the infants, as funding limitations precluded activity monitoring in all babies. Nonetheless, studying spontaneous motor activity with more advanced techniques promised to provide new information about the effects of
Results
There were no differences between anemic and nonanemic groups in characteristics related to gender, birth weight, growth at 6 months, breast feeding, mental or motor development test scores (see Table 1).
Pearson correlations were computed to determine whether motor activity was correlated with child or family characteristics. Even with a relatively liberal level of statistical significance (p<0.10), there was only one significant correlation (between the primary caregiver's level of education
Discussion
Using sophisticated quantitative techniques, this study points to a reduction in spontaneous motor activity during wakefulness around an afternoon nap in young infants who had iron-deficiency anemia. With the exception of Edgerton et al.'s [8] small study of 16 plantation workers in Sri Lanka, we have been unable to identify other studies that apply such advanced methodology to the question of the effects of iron-deficiency anemia on human motor activity. We therefore present our results
Acknowledgments
Funded by the U.S. National Institutes of Health (R01 HD33487 and T37 TW00035) and the Chilean Agency for Funding in Science and Technology (FONDECYT, #1000657) grants.
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2013, Early Human DevelopmentCitation Excerpt :Nonetheless, we considered that studying spontaneous motor activity for 48 continuous hours with more advanced techniques promised to provide new information about the long-lasting effects of IDA in infancy. Detailed descriptions of the population and other findings during infancy and the preschool period have been published elsewhere [7,24,36–38]. Participants in this study had been born healthy, at term, weighing ≥ 3.0 kg and were free of acute or chronic health problems as infants (for further details of inclusion criteria, see [35,36]).