The behaviour and development of infants with iron deficiency anaemia : systematic observation of 9-month-old Pemban caregiver-infant dyads.
Dellis, Andrew Mark.
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Background: The Zanzibar Infant Nutrition Campaign is a large-scale randomised control trial investigating the effects of iron and zinc supplementation on the morbidity and mortality of infants and young children on Pemba Island, Zanzibar, Tanzania. The Child Development Study is a substudy of the larger ZINC control trial assessing the effects of 12 months of iron and zinc supplementation on motor and language development. The Caregiver-Infant Interaction Study is a substudy of the Child Development Study, assessing the effects of 1 to 3 months of iron and zinc supplementation on caregiver-infant interaction among 9-month-old dyads. This thesis reports on the dyads enrolled in the Caregiver-Infant Interaction Study. While not examining treatment effects1 • Formulate behavioural and developmental hypotheses specific to a population of 9-month-old caregiver-infant dyads affected by a history of IDA , hypothesised disturbances in the behaviour and development of infants affected by a history of iron deficiency anaemia (IDA) are examined. Objectives: • Develop a hypothesis-driven observational coding system and establish the psychometric properties of this measure • Test hypotheses about the relationship between a history of IDA and the behaviour and development of 9-month-old caregiver-infant dyads Rationale: Iron deficiency anaemia is the most common nutritional disorder in the world. Prevalence is especially high among women, young children and infants in developing countries. As a public health concern, the effects of IDA are various and insidious, however the relationship between IDA and infant behaviour and development is not known. The majority of studies concerned with the impact of IDA in infancy have relied on global developmental scales, such as the Bayley Scales of Infant Development (Bayley, 1969, 1993). While infants with IDA consistently score worse than non-anaemic comparisons on mental and motor subscales, the value of this form of assessment is known to be limited. Apart from being of questionable validity as indices of abilities or functions (e.g., Fagan & Singer, 1983), the scores and ratings produced by traditional developmental scales are not designed to assess the specific functions hypothesised to be affected by IDA (Lozoff, De Andraca, Castillo, Smith, Walter & Pino, 2003). Over-reliance on this kind of measure thus rules out meaningful hypothesis-driven research. Recently, malnutrition researchers have begun to made use of systematic behavioural observation as a means of assessment. While a promising approach, extant research is limited to only two studies (see Footnote 6), and both of these have been conducted by the same research group. Moreover, these studies have relied on fairly rudimentary behavioural coding to examine a version of the ‘Functional Isolation Hypothesis', originally proposed some time ago in the infrahuman literature (Levitsky & Barns, 1972, 1973). More sophisticated hypotheses are available, especially given the ready availability of insights from developmental psychobiology and cognitive science. Design: A correlational design was used to examine the behaviour and development of 9-month old caregiver-infant dyads with a history of IDA. Setting: Wete District, Pemba Island, Zanzibar, Tanzania. Participants: 160 Caregiver-infant dyads assessed observationally at 9-month of age. Main Outcome Measure: Systematic observational coding. Main Findings: Infants with a history of more severe IDA spent significantly less time in high energy states during free play, and their caregivers made less physically demanding requests. A history of IDA also correlated with developmental disturbances in postural control. Affectively, IDA infants were hypo-responsive, and caregivers showed more (overt) positive affect for healthy males, but not females. Caregivers coordinated actions and vocalizations less often during interaction with infants affected by a history of IDA. Conclusion: A history of IDA among 9-month old infants is related to behavioural and developmental disturbances in both motor and socio-cognitive domains. Note to reader: The present research was first submitted as a Masters dissertation in 2008. The author was subsequently offered the opportunity rather to upgrade to a Doctoral thesis and resubmit the work as PhD. Chronologically then, studies which did not inform the design and development of the coding system used for data collection, or which published findings after the first submission of the present work, are discussed in the final chapter.