Summary: A new longitudinal study shows that simple cognitive assessments in infancy can modestly predict cognitive ability three decades later. Researchers followed more than 1,000 twins beginning at seven months of age, recording behaviors such as vocalizations, task focus and novelty preference to evaluate early cognitive functioning.
By age 30, early infant assessments accounted for roughly 13% of the variance in adult cognitive scores. The research also highlights a measurable influence from the environment in the first years of life: shared environmental factors before age one or two explained about 10% of later cognitive differences. While genetic factors remain a dominant influence on general cognitive ability (GCA), the findings underscore how early-life experiences contribute to long-term cognitive outcomes.
Key Facts:
- Long-term prediction: Infant cognitive tests predicted up to 13% of cognitive performance at age 30.
- Early environmental impact: Environmental influences before age one explained about 10% of adult cognitive variability.
- Strongest infant signals: Novelty preference and task orientation in infancy were the most predictive early measures.
Source: University of Colorado
Overview
Watching a baby babble, explore objects and respond to new stimuli provides more than charming moments — it can offer measurable information about cognitive development that persists into adulthood. New research from the University of Colorado Boulder, published in PNAS, tracked cognitive trajectories in the Colorado Longitudinal Twin Study to investigate how early-life behavior and genetics relate to adult cognitive ability.
What twins can teach us
General cognitive ability (GCA) — a composite measure similar to IQ that encompasses learning, reasoning and problem-solving — has long been shown to be relatively stable from childhood onward. Tests administered in middle childhood or adolescence typically predict adult scores well. However, less is known about whether signals present in infancy carry forward into adult cognitive functioning.
Researchers led by Daniel Gustavson and Chandra Reynolds analyzed data from 1,098 participants enrolled in the Colorado Longitudinal Twin Study, which began in 1985 to disentangle genetic and environmental influences on development. The team collected repeated assessments across life stages through laboratory evaluations, home visits, surveys and behavioral testing.
As early as seven months, infants were evaluated on a set of seven cognitive indicators, including rates of vocalization, the ability to remain on task (task orientation), and novelty preference — the tendency to favor new toys or stimuli over familiar ones. Age-appropriate cognitive tests were then administered at multiple points in development up to age 30.
The researchers found that infant cognitive measures explained about 13% of the variability in cognitive scores at age 30. Among the infant measures, novelty preference and task orientation produced the strongest predictive signals, though the overall effect size is modest. “We do not want to imply that cognition is fixed by seven months,” Gustavson noted, “but it is notable that simple infancy tests can correlate with complex adult cognitive outcomes decades later.”
Nature, nurture or both?
To separate genetic from environmental contributions, the study leveraged the twin design: identical twins share 100% of their genes, while fraternal twins share roughly 50%. Greater similarity among identical twins compared with fraternal twins indicates stronger genetic influence. The team also used DNA from blood or saliva to support genetic analyses.
Genetic factors accounted for a substantial portion of adult GCA, with genetic influences measured by age 7 explaining about half of the variation in scores at age 30. Still, environmental factors in the earliest years played a measurable role: approximately 10% of adult cognitive variability could be traced to shared environmental influences operating before age one or two. The data suggest that as children age, genetic influences tend to increase while the relative impact of early shared environment declines.
Reynolds, whose work includes research on Alzheimer’s and dementia, emphasizes that cognitive aging is a lifelong process. Early-life environmental investments, such as enriched learning opportunities and stable caregiving, might therefore contribute not only to school and occupational outcomes but potentially to resilience against age-related cognitive decline.
A polygenic score for intelligence
The study also evaluated polygenic scores (PGSs), which aggregate the small effects of thousands of genetic variants into a single index estimating genetic predisposition for a trait like cognitive ability. Using large genomic datasets, the researchers calculated PGSs for the adult twins and compared these scores to their cognitive measures across development.
While there is no single “intelligence gene,” combining many variants produces predictive power. The study found that PGSs for adult GCA and educational attainment predicted cognitive ability from ages 1–2 onward (βs ranged from 0.09 to 0.44), but they did not predict the specific infant cognition measures captured at seven to nine months. This pattern indicates that genomic predictors align with later cognitive development, while very early infant behaviors carry independent information about later outcomes.
Implications and conclusions
Overall, the research indicates that genetic and environmental influences on GCA show notable stability by around age three. Infant cognition measures are less predictive than later childhood assessments, but they nonetheless provide a modest early signal. Twin analyses suggested that 22% of adult GCA variance was accounted for by genetic influences present at age three or earlier, with an additional 10% explained by shared environmental factors detectable at age one to two.
These findings reinforce the value of both family-based and genomic data for understanding how genetic and environmental contributions to cognition change across the lifespan. They also highlight early childhood — including the pre-preschool environment — as a critical window where interventions and supportive environments may yield long-term cognitive benefits.
About this research
Author: Lisa Marshall
Source: University of Colorado
Contact: Lisa Marshall – University of Colorado
Image: Image credited to Neuroscience News
Original research: Closed access. “Stability of general cognitive ability from infancy to adulthood: A combined twin and genomic investigation” by Daniel Gustavson et al., published in PNAS. DOI cited in the original report.
Abstract
Stability of general cognitive ability from infancy to adulthood: A combined twin and genomic investigation
Measures of general cognitive ability (GCA) are known to be highly stable from adolescence onward, particularly for genetic influences. In early life (before age 3), GCA measurement is less reliable, and the relationship between infant measures and adult GCA is less well understood. Using data from the Colorado Longitudinal Twin Study (N = 1,098), the authors examined GCA across five time points (years 1–2, 3, 7, 16 and 29) and evaluated how cognitive measures at 7 and 9 months relate to later GCA.
Two infant measures — object novelty preference and tester-rated task orientation — predicted adult GCA with correlations of r = 0.16 and r = 0.18, respectively. Correlational analyses showed increasing stability of GCA across development (r = 0.39 to 0.85 between year 1–2 and adulthood). Twin analyses indicated that 22% of variance in adult GCA was attributable to genetic influences already present by age 3 or earlier, with an additional 10% explained by shared environmental influences at age 1–2. Polygenic scores for adult GCA and educational attainment predicted GCA from age 1–2 onward (βs = 0.09 to 0.44) but did not predict infant cognition. The results imply that genetic and environmental contributions to GCA are substantially stable by age 3, while infant cognition measures are less predictive of later ability.