To evaluate the impact of early iron-deficiency anemia (IDA) on central nervous system development, auditory brainstem responses (ABR) during spontaneous naps were studied in 28 6-month-old Chilean infants (14 IDA and 14 controls). All infants were born full-term, BW > 3000 gm, and were free of acute or chronic illness. 12 IDA and 10 control infants were re-evaluated at 18 mo, after 6 mo of therapeutic iron and 6 mo of prophylactic iron. ABR elicited monaurally at 75 and 85 dB HL were averaged in a Nicolet C4 machine. Absolute and interpeak latency values were significantly longer (p<.05) among 6-mo-old IDA infants. Central Conduction Time (CCT; I-V interval) was longer in IDA than control group (4.62 ± 0.19 ms v. 4.50 ± 0.21 ms, p=.05). Despite increase in amplitude of waves and reduction in latency values with advancing age in both groups, CCT remained longer in IDA infants at 18 mo (4.44 ± 0.15 ms vs. 4.21 ± 0.17 ms in controls, p=0.002). CCT is considered an index of CNS maturation, since maturation of nerve fibers and synaptic relays lead to an exponential reduction in CCT from birth to 24 months. The results show that 6-month-old infants with iron-deficiency anemia have less mature auditory brainstem responses, indicating that iron-deficiency anemia adversely affects CNS development. Differences persisted after 1 year, despite appropriate iron therapy. Impaired myelination is hypothesized to be the explanation, given iron's role in myelin formation and maintenance. Funded by NICHD, Nestle Foundation, and FONDECYT-Chile.

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