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Infant developmental milestones and adult intelligence: A 34-year follow-up
Trine Flensborg-Madsen1, Erik Lykke Mortensen2
1Unit of Medical Psychology, Institute of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353 Copenhagen K, Denmark.
Insights
Faster infant motor development is linked to higher adult intelligence, particularly for children from lower social status backgrounds. This study highlights the importance of early motor milestones for long-term cognitive outcomes.
Area of Science:
- Developmental Psychology
- Cognitive Neuroscience
- Pediatrics
Background:
- Previous research indicates a link between early motor development and later intelligence in childhood and adolescence.
- However, the association between infant motor skills and adult intelligence remains under-explored.
Purpose of the Study:
- To examine if the age of achieving 12 infant motor developmental milestones correlates with adult intelligence.
- To assess the impact of various factors including sex, socioeconomic status, and perinatal conditions on this association.
Main Methods:
- Utilized data from the Copenhagen Perinatal Cohort, tracking 9125 children's motor milestones.
- A subsample (1155 individuals) underwent intelligence testing using the Wechsler Adult Intelligence Scale (WAIS) in adulthood (20-34 years).
- Multiple linear regression analysis was employed to analyze associations, adjusting for confounding variables.
Main Results:
- Later achievement of infant motor milestones was associated with lower adult IQ scores, especially Performance IQ.
- While correlations were generally small, significant interactions revealed that the association was stronger in offspring of lower social status parents.
- These findings persisted after adjusting for confounding factors.
Conclusions:
- This study is the first to demonstrate significant interactions between parental social status and the early motor development-intelligence link.
- The results suggest that early motor development may be a more critical predictor of adult intelligence for individuals from lower socioeconomic backgrounds.
Background:
A number of studies suggest a positive association between faster infant motor development and intellectual function in childhood and adolescence. However, studies investigating the relationship between infant motor development and intelligence in adulthood are lacking.
Aims:
To investigate whether age at achievement of 12 motor developmental milestones was associated with adult intelligence and to evaluate the influence of sex, parental social status, parity, mother's cigarette consumption in the last trimester, gestational age, birthweight, and birth length on this association.
Methods:
Mothers of 9125 children of the Copenhagen Perinatal Cohort recorded 12 developmental milestones during the child's first year of life. A subsample of the cohort comprising 1155 individuals participated in a follow-up when they were aged 20-34 years and were administered the Wechsler Adult Intelligence Scale (WAIS). Associations between motor developmental milestones and IQ were analysed by multiple linear regression adjusting for potential confounding factors.
Results:
Later acquisition of infant developmental milestones was associated with lower subsequent IQ, and the majority of significant associations were found for Performance IQ. Correlations were generally small (r < 0.10), but significant interactions were found between parental social status and age of attaining developmental milestones, with associations being significantly stronger in the offspring of lower social status parents. The effects remained significant after adjusting for possible confounding factors.
Conclusion:
This is the first study to find significant interactions with parental social status, thereby suggesting that associations between early motor development and intelligence are stronger in infants of low social status parents.
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