ADHD in formerly institutionalized children tied to slower physical and brain growth

A new study published in the Journal of Child Psychology and Psychiatry provides insight into how early-life institutional care affects physical and brain development—and how these developmental patterns are linked to attention-deficit/hyperactivity disorder (ADHD). Children who were raised in institutions before being placed in foster care showed delayed physical growth and changes in brain activity, particularly if foster placement occurred later in childhood. These delays were more pronounced in children who went on to develop ADHD, suggesting that prolonged adversity in early life may contribute to lasting differences in both body and brain development.

ADHD is a neurodevelopmental condition marked by persistent patterns of inattention, hyperactivity, and impulsivity. While it is common in the general population, the condition appears to be significantly more prevalent among children who have experienced early institutionalization. Past studies have already shown that children raised in institutional care are at greater risk of ADHD and physical growth delays, but it has remained unclear whether these outcomes share a common developmental pathway.

The present study aimed to explore that link using data from the Bucharest Early Intervention Project (BEIP)—a long-running randomized trial comparing outcomes among institutionalized children assigned either to foster care or to remain in institutional settings.

Researchers followed 177 children in Romania over the course of 16 years. Among them, 136 children had been raised in institutions. These children were randomly assigned either to continue with institutional care or to be placed in foster homes arranged by the study. A comparison group of 64 children who had never been institutionalized was also included. All participants were assessed multiple times from infancy to adolescence using physical growth measurements and electroencephalography (EEG), which tracks electrical activity in the brain. ADHD diagnoses were determined based on structured interviews with caregivers at two time points: at 54 months and again at age 12.

The results revealed a consistent pattern: children who remained in institutional care showed delayed physical growth and brain development, especially those who met criteria for ADHD. About 27% of institutionalized children were diagnosed with ADHD, compared to just 4.5% of children who had never been institutionalized. Among those placed into foster care, ADHD rates were significantly lower for children placed before the age of two, suggesting that early intervention plays a key role in reducing long-term developmental risks.

Physical growth data showed that children in institutional care were shorter, had smaller head circumferences, and weighed less than never-institutionalized children. Those placed in foster care did somewhat better, but only if they were placed at a younger age. Importantly, children with ADHD had even more delayed physical growth trajectories, particularly when it came to height and head circumference. Among children who were placed into foster care before age two, those with ADHD still showed slower growth than those without the disorder.

In terms of brain development, the study focused on two measures captured by EEG: peak alpha frequency and the theta-beta ratio. These are indicators of how the brain is maturing and organizing itself. Normally, peak alpha frequency increases with age, reflecting greater brain efficiency, while the theta-beta ratio tends to decrease as brain networks become more specialized. The researchers found that institutionalized children had slower increases in peak alpha frequency, especially those placed into foster care later in life. However, peak alpha frequency was not directly associated with ADHD diagnosis.

In contrast, the theta-beta ratio was significantly lower in children with ADHD, but only within the foster care group. This finding was unexpected, as elevated theta-beta ratios have often been associated with ADHD in other studies. The authors suggest that the lower ratio in these children may reflect unique developmental trajectories resulting from early adversity and subsequent intervention.

To investigate whether rapid physical growth after placement in foster care might negatively impact brain development—a theory known as the “maturational trade-off” hypothesis—the researchers used cross-lagged statistical models. These models allowed them to examine how changes in physical growth might influence brain activity over time, and vice versa. The results provided no support for the idea that faster physical growth comes at the expense of brain maturation. In fact, among children with ADHD, greater height at age 12 predicted more typical brain activity patterns at age 16.

This study adds to growing evidence that early childhood experiences—especially extreme deprivation—have lasting effects on both physical and neural development. While high-quality foster care can help mitigate some of these effects, the data suggest that children who go on to develop ADHD may not benefit as much from these interventions as others. The reasons for this are not entirely clear. One possibility is that ADHD itself may interfere with the ability to fully benefit from enriched environments. Another is that genetic factors contribute to both ADHD risk and the likelihood of early institutionalization, such as when biological parents struggle with mental illness or substance use.

The researchers acknowledge some limitations. The sample size was relatively small, which may have limited their ability to detect subtle effects. ADHD diagnoses were based on reports at only two time points, and about one-third of children had data from just one assessment. EEG methods changed partway through the study, which could have influenced results. In addition, the caregiving experiences of children in the foster care and institutional groups overlapped more than intended, due to placement disruptions and changes in living situations. Finally, the study could not account for genetic influences or prenatal exposures that might have affected development.

Despite these limitations, the study has several strengths. It is one of the only randomized controlled trials of foster care placement, allowing for stronger inferences about the effects of early environment on development. The use of repeated measures over time also enabled researchers to trace growth patterns across critical developmental periods.

The study, “Physical and neurophysiological maturation associated with ADHD among previously institutionalized children: a randomized controlled trial,” was authored by Anne B. Arnett, Martín Antúnez, Charles Zeanah, Nathan A. Fox, and Charles A. Nelson.