Early neglect may disrupt how the brain fine-tunes itself during adolescence

Children exposed to severe psychosocial deprivation early in life showed lasting differences in how their brain activity developed during adolescence, according to a study published in the Proceedings of the National Academy of Sciences. These altered brain dynamics were associated with poorer performance on a task requiring attention and self-control.

Adolescence is a major period of brain development. During these years, young people generally become faster and more accurate at controlling their attention, managing distractions, and responding to changing demands. Brain networks also become more stable and efficient, partly through a process called synaptic pruning, in which weaker connections between brain cells are eliminated and stronger ones are reinforced.

Computer models suggest that pruning helps brain activity settle back to its typical pattern more quickly after being knocked off course, which may support more efficient thinking. The researchers wanted to know whether severe deprivation early in life could interrupt this process.

Psychosocial deprivation can occur when children grow up without consistent caregiving, stimulation, and social interaction. Institutional settings may provide food and shelter but still fail to offer the stable, responsive relationships that are important for healthy development.

Led by Marta Andujar of the National Institute of Mental Health, the team used data from the Bucharest Early Intervention Project, a long-running randomized controlled trial in Romania. When the project began, young children living in state-run institutions, all younger than about two and a half, were randomly assigned either to move into high-quality foster care or to continue receiving the usual institutional care.

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The analysis included 163 participants. Fifty-two had been randomly placed in foster care, and 51 had been randomly assigned to continue in institutional care, although Romanian child protection authorities later moved many children in that group to other placements. A comparison group of 60 children who had never lived in an institution was recruited from the community. Participants were assessed in follow-ups that began at ages 12, 16, and 21, with average ages at those visits of about 12.7, 16.9, and 23.3 years.

Participants completed a Flanker task, which involves responding to a central arrow while ignoring surrounding arrows that point either in the same direction or in the opposite direction. The task measures the ability to focus attention and override an automatic response.

While participants completed the task, the researchers recorded the brain’s electrical activity using electroencephalography (EEG). They then used a mathematical model to measure how quickly moment-to-moment deviations in each person’s brain activity, the ways a single trial differed from that person’s typical response, faded back toward the typical pattern. A higher value indicated that these deviations lingered longer before settling back.

Across all groups, these values decreased with age, suggesting that brain activity normally becomes quicker to stabilize during adolescence. However, participants who had experienced institutional care showed consistently higher values than those who had never been institutionalized. The foster care group did not differ from the group assigned to continued institutional care, meaning this brain measure showed no clear benefit of foster care. That contrasts with earlier findings in the same children, which showed some recovery after foster care in other brain signals, though the new study used a different and more fine-grained measure.

Behavioral results told a similar story. Never-institutionalized participants were more accurate overall than both groups with institutional histories, which did not differ from each other. On a measure combining speed and accuracy, foster care appeared to help somewhat, but the authors describe this recovery as modest and limited.

Participants whose brain activity took longer to settle also tended to perform less efficiently on the task, based on the combined measure of speed and accuracy. This link was negligible at age 12 but grew stronger at 16 and 21. Statistical analyses suggested that the neural differences accounted for part of the performance gap between participants with and without institutional histories.

“These findings demonstrate that early deprivation leaves a lasting imprint on the developmental trajectory of neural dynamics, affecting the maturation of brain systems underlying cognitive control,” the authors concluded.

The study has some limitations. Although children were randomly assigned to foster care or institutional care, the never-institutionalized comparison group was not randomized, so differences between that group and the others could partly reflect factors other than deprivation. The sample was also relatively small, and children’s placements and later life experiences varied after the trial began.

In addition, the link to synaptic pruning is an interpretation rather than a direct measurement, since EEG cannot measure connections between brain cells. The authors note that this explanation still needs to be tested directly, for example in animal studies that combine brain recordings with anatomical data.

The study, “Early psychosocial deprivation alters the refinement of neural dynamics across adolescence,” was authored by Marta Andujar, Lucrezia Liuzzi, Daniel S. Pine, Charles A. Nelson III, Charles H. Zeanah, Nathan A. Fox, and Bruno B. Averbeck.