Resting brain activity observed during early childhood holds significant predictive value for long-term cognitive outcomes extending into adulthood, according to new research published in Developmental Cognitive Neuroscience. The discovery contributes to a deeper understanding of how factors during critical developmental periods shape an individual’s cognitive trajectory over time.
Resting brain activity, often measured through techniques like electroencephalogram (EEG), is thought to reflect the brain’s intrinsic functioning. This activity pattern can serve as a biomarker of brain health and development. The researchers want to investigate whether variations in this early brain activity can provide insights into long-term cognitive trajectories.
“I have always been interested in early individual differences and the relations between brain activity and behaviors,” said study author Enda Tan, a postdoctoral associate at the University of Maryland, College Park. “In this study, I was particularly interested in whether resting brain activity, a measure commonly used in developmental research as an index of brain development, has meaningful implications for predicting long-term outcomes.”
To provide a comprehensive understanding, the study leveraged multiple timepoints across development, from early childhood to adulthood. This approach enabled the researchers to investigate how early differences in brain activity relate to cognitive development over an extended period.
The study involved a sample of 202 children from the Bucharest Early Intervention Project, a research project that focuses on studying the effects of early psychosocial deprivation on child development and the potential benefits of intervention, particularly foster care, for children who have experienced institutional rearing.
Data was collected from the children at several time points: when they were infants (baseline), at 30 months, and at 42 months. The researchers used EEG technology to measure brain activity and conducted cognitive tasks to assess their developmental progress. When the children reached 18 years of age, their cognitive abilities were evaluated using an IQ test.
Tan and his colleagues found that resting brain activity during early childhood could predict cognitive outcomes when the participants reached 18 years of age. Specifically, the researchers found that the amount of brain activity in the theta frequency band during resting periods at baseline, 30 months, and 42 months correlated with the children’s IQ at 18 years old. Other frequency bands (alpha, beta, gamma) did not show significant correlations with IQ.
Theta waves fall within the frequency range of approximately 4 to 8 Hertz. They are relatively slow brainwave patterns that are commonly associated with different mental states and activities, such as memory processes and the transition between being awake and falling asleep.
“Our findings suggest that early individual differences in resting brain activity may be associated with IQ in adulthood,” Tan told PsyPost.
Further analysis showed that the resting theta activity in early childhood was linked to specific cognitive abilities at 18 years, including perceptual reasoning, working memory, and processing speed. This suggests that the brain’s theta activity during rest might be tied to these particular cognitive skills later in life.
“For me, what is striking is that brain activity measured during resting state (i.e., when children were sitting ‘at rest’ and not actively engaged in a specific cognitive task) predicted cognitive outcomes more than 14 years later,” Tan said. “This is remarkable considering the large number of factors (e.g., maturation, education) that could affect the trajectory of cognitive development during this time span.”
Additionally, the researchers found that experiences like institutional rearing and the timing of foster care placement had significant effects on cognitive development, with resting theta power acting as a mediator between these experiences and long-term cognitive outcomes.
Institutional rearing (such as being placed in an orphanage) was associated with higher resting theta power at baseline, which in turn was associated with lower developmental quotient (DQ) at 30 and 42 months, and ultimately lower IQ at 18 years. Similarly, later placement into foster care (as opposed to earlier placement) was linked to higher resting theta power at 30 months, which then led to lower DQ at 42 months and lower IQ at 18 years.
“The study also provides evidence that institutional rearing and foster care intervention influenced resting brain activity early in life, which in turn predicted cognitive outcomes into adulthood,” Tan told PsyPost.
As with any study, however, the findings include some caveats.
“These findings are based on a specific sample,” Tan explained. “Therefore, the generalizability and robustness of the effects should be tested in future studies using other samples. Also, although we found evidence for associations between early brain activity and cognitive outcomes, the mechanisms underlying these associations remain unclear. Future research should explore what neural and cognitive mechanisms explain these associations.”
“This study is part of the Bucharest Early Intervention Project (BEIP), a randomized controlled trial of foster care as an alternative to institutional rearing. I would encourage people to read about this project if they are interested in how institutional rearing and foster intervention influence neural, cognitive, and socioemotional processes throughout development.”
The study, “Resting brain activity in early childhood predicts IQ at 18 years“, was authored by Enda Tan, Alva Tang, Ranjan Debnath, Kathryn L. Humphreys, Charles H. Zeanah, Charles A. Nelson, and Nathan A. Fox.