Academic Achievement in Children With Oral Clefts Versus Unaffected Siblings

Previous studies have found that children with isolated oral-facial clefts (OFC) have elevated risk for learning problems, with proposed mechanisms including differences in brain morphology or function, social stigmatization, and “downstream” effects of early impairment in speech and language (Richman, McCoy, Conrad, & Nopoulos, 2012). With regard to biological mechanisms, several authors have proposed that the embryological events that result in clefting also affect early brain development. Studies by Nopoulos and colleagues (Nopoulos, Langbehn, Canady, Magnotta, & Richman, 2007; Nopoulos et al., 2002; van der Plas, Conrad, Canady, Richman, & Nopoulos, 2010) provide support for this hypothesis, with differences revealed in brain structure in individuals with OFC compared to unaffected controls. Further, these authors have found associations between regions of structural difference and neurobehavioral outcomes (Nopoulos et al., 2010; Shriver, Canady, Richman, Andreasen, & Nopoulos, 2006). Based on the social psychology literature related to facial attractiveness (Langlois et al., 2000), it has also been proposed and there is some evidence to suggest that clefting affects the perceptions and expectations of teachers, which can in turn have a deleterious effect on achievement (Richman, 1978). Recent studies have focused on the long-term effects of speech and language deficits associated with clefting, which may interfere with the development of early reading and related academic skills (Chapman, 2011; Conrad, McCoy, Devolder, Richman, & Nopoulos, 2014). Finally, although not well-studied, demographic and maternal health factors that place infants at risk for clefting (e.g., low socioeconomic status, maternal nutrition, exposures to alcohol or tobacco, genetic vulnerability) might also affect development and academic achievement. To date, most of the research showing an association between OFC and academic achievement has relied on small clinic samples compared to test norms or unaffected control groups (Broder, Richman, & Matheson, 1998; Collett, Stott-Miller, Kapp-Simon, Cunningham, & Speltz, 2010; Conrad, McCoy, Devolder, Richman, & Nopoulos, 2014). Three recent population-based studies of children with OFC compared with unaffected peers have corroborated the findings from earlier clinical investigations (Persson, Becker, & Svensson, 2012; Wehby et al., 2014; Yazdy, Autry, Honein, & Frias, 2008). In the most recent of these studies, we compared ∼600 children with OFC with a comparison group of nearly 2,000 unaffected classmates (Wehby et al., 2014). Across all grade levels from elementary through high school, children with OFC had lower scores on measures of reading, math, language, science, and social studies. These group differences were only slightly reduced when controlling for parental education, race/ethnicity, and prenatal exposures to alcohol or tobacco. As is true in most population-based studies, there were potential confounding variables that we could not address in this study. For example, parental education was used to control for socioeconomic status (SES); however, parental education alone may not capture qualities of the home environment that can affect academic achievement such as parents’ investment in their child’s education and home activities to facilitate early learning (McGrath et al., 2007; Phillips & Lonigan, 2009; Wehby, McCarthy, Castilla, & Murray, 2012). In the current study, we used unaffected siblings as a comparison group to examine the influence of selected shared and unshared features of the home environment. We identified children with OFC from the Iowa Registry for Congenital and Inherited Disorders (IRCID) and siblings from birth certificates, and obtained birth record and academic achievement data. Academic achievement was assessed by the Iowa Testing Programs (ITP), which routinely tracks academic progress for all children in the state of Iowa. We tested the hypothesis that children with OFC would perform lower on academic achievement tests than their siblings. Among unaffected siblings, we also evaluated factors that may uniquely affect the achievement of siblings of a child with OFC, factors usually assumed to be null in a sibling comparison model. For example, the academic performance of unaffected siblings could be compromised by the diversion of parents’ attention and resources away from the sibling and toward the affected child. We examined this possibility in post hoc analyses of achievement in relation to the differences in birth order and age between the child with OFC and his or her sibling, assuming that siblings born subsequent to the affected child and younger in age would be more impacted than siblings born before the affected child and more distant in age. We also examined whether achievement of unaffected siblings was influenced by the sex match between siblings and affected children (same or opposite) and cleft type (lip only, lip and palate, palate only).