Link to the article in English:

The present study aims to determine to what extent relational withdrawal at the age of one is associated with the child’s IQ at the end of the preschool period. A total of 1,045 children from the EDEN mother-child cohort were assessed for relational withdrawal behaviors at the age of one by trained midwives, using the Alarm Distress BaBy (ADBB) scale. The midwives also examined the infants’ language development and motor skills at this age. At the age of 5-6 years, IQ scores were based on the WPPSI-III.

After adjusting for a wide range of pre- and postnatal environmental factors, and for language and motor skills scores at one year, children with relational withdrawal at one year (ADBB ≥5; N = 195) had significantly lower IQ scores at 5-6 years (−2.81 IQ points; p = 0.007) compared to children without relational withdrawal (ADBB <5; N = 847). When motor and language skills at one year were included in the previous model, no association between relational withdrawal and IQ at 5-6 years was found.

Being relationally withdrawn at one year is associated with lower IQ scores at 5-6 years. The potential influence of these developmental aspects on each other (withdrawal behavior and language/motor skills) may occur early in development. Our results improve our understanding of the outcomes of early social withdrawal and call for early detection of delays in the acquisition of language and motor skills among socially withdrawn young children.

My opinion as an expert on the subject:
This study sheds light on an often-neglected aspect of child development: the impact of relational withdrawal on IQ. As a clinician and expert in this field, I find these results particularly relevant to clinical practice. They emphasize the importance of early assessment and intervention, not only for relational withdrawal itself but also for the related language and motor skills. This research reinforces the idea that child development is an interconnected process, where one area can influence another. It underscores the need for a holistic approach in assessing and supporting the healthy development of the child.