To which extent social withdrawal at the age of 1 year is associated with IQ at 5–6 years old? Results of the EDEN mother–child cohort

The present study aims to determine to which extent social withdrawal at 1 year is associated with the child’s IQ at the end of the preschool period. Children (N = 1045) from the EDEN mother–child cohort were assessed for social withdrawal behaviours at 1 year by trained midwives using the Alarm Distress BaBy (ADBB) scale. Midwives also examined infants’ language and motor development at 1 year. At the age 5–6 years, IQ scores were based on the WPPSI-III. Linear regression models were used to determine the association between IQ and ADBB, adjusted for a broad range of pre- and postnatal environmental factors and for language and motor skills scores at 1 year. After adjusting for environmental factors, children with social withdrawal at 1 years (ADBB ≥5; N = 195) had significantly lower IQ scores at 5–6 years (−2.81 IQ points; p value 0.007) compared to children without social withdrawal (ADBB <5; N = 847). When motor and language skills at 1 year were included in the previous model, no association between social withdrawal and IQ at 5–6 years was found. Being socially withdrawn at 1 year is associated with lower IQ scores at 5–6 years. The potential influence of these developmental aspects on each other (withdrawal behaviour and language/motor skills) may occur early in development. Our results improve our understanding of the outcomes of early social withdrawal behaviour and call for early detection of delay in acquisition of language/motor skills among socially withdrawn young children.