Harsh parenting in childhood may alter brain development and lead to behavioral issues in girls

New research suggests a potential biological reason why harsh parenting in early childhood can lead to behavioral problems in girls. Scientists found that girls who experienced harsh parenting showed differences in the development of brain connections involving the amygdala, an area important for emotions, and that these brain differences may help explain the link between early parenting and later behavioral challenges. The findings were published in Psychological Medicine.

It’s increasingly recognized that a child’s early experiences, including parenting styles, play a powerful role in shaping their developing brain and future well-being. Harsh parenting, encompassing actions like physical punishment and frequent displays of anger, is considered a significant source of stress for young children and can disrupt their emotional and social growth, potentially leading to behavioral problems as they mature.

Although earlier research suggested a link between negative early experiences and later difficulties like aggression and rule-breaking, many studies only provided a limited view, either examining the brain at a single point or focusing on older age groups. The new study set out to provide a more complete picture by following brain development across multiple time points in childhood. Recognizing that boys and girls may respond differently to stress, the researchers specifically investigated potential differences in how harsh parenting might affect brain development and behavior in each sex.

For their study, the researchers utilized data from a long-term study called “Growing Up in Singapore Towards healthy Outcomes” (GUSTO). This study has been collecting detailed information on children from birth onwards. For this specific research, they used brain scans taken at four different times as the children grew, starting at age four and a half and continuing until age ten and a half.

This longitudinal approach, with multiple brain scans over time, is significant because it allows researchers to track brain development within each individual child, rather than just comparing different children at different ages. This is especially important in childhood, where brain development can vary greatly from child to child.

The researchers first looked at whether harsh parenting in early childhood, specifically at age four and a half, was associated with behavioral problems at age ten and a half. Because they were interested in understanding the brain basis of these associations, they then investigated whether harsh parenting was related to how the amygdala develops over time. The amygdala is a key area of the brain involved in processing emotions, particularly in response to threats or stressful situations. They focused on two aspects of amygdala development: its size and its functional connectivity, meaning how well it communicates with other brain regions.

To measure harsh parenting, mothers completed a questionnaire when their children were four and a half years old. This questionnaire, called the Parenting Style & Dimensions Questionnaire – Short version, assessed different aspects of parenting. The researchers focused on the subscales related to physical coercion, verbal hostility, and punitive discipline, which together are considered indicators of harsh or authoritarian parenting.

When the children were ten and a half years old, their behavioral problems were assessed using two different methods. Parents completed the Child Behavior Checklist, a widely used questionnaire that asks about a range of emotional and behavioral problems in children. This checklist provides scores for both internalizing problems (like anxiety and withdrawal) and externalizing problems (like aggression and rule-breaking). To also get the children’s own perspective, the researchers used the Children’s Depression Inventory 2nd Edition, a self-report questionnaire that measures depressive symptoms in children.

The study’s findings revealed that harsh parenting in early childhood was associated with externalizing problems, such as aggression and rule-breaking, at age ten and a half. However, harsh parenting was not found to be associated with internalizing problems, such as anxiety or depression, at the same age. Interestingly, when the researchers looked at boys and girls separately, they found that the link between harsh parenting and externalizing problems was primarily evident in girls, not in boys.

Regarding brain development, the researchers found that harsh parenting was not directly associated with the size of the amygdala. However, it was linked to the developmental trajectories of functional connectivity between the amygdala and several other brain regions, including the anterior cingulate cortex (ACC), orbital frontal cortex, and dorsolateral prefrontal cortex.

Specifically, children who experienced higher levels of harsh parenting showed a different pattern of change in these connections over time compared to children who experienced less harsh parenting. Again, these effects appeared to be somewhat different for boys and girls. For example, the association between harsh parenting and the developmental trajectory of amygdala-ACC connectivity was mainly observed in girls.

Importantly, the mediation analysis provided evidence that changes in amygdala-ACC functional connectivity might be a neural mechanism explaining the link between harsh parenting and externalizing problems in girls. The results suggested that girls who experienced harsher parenting showed a faster decrease in amygdala-ACC connectivity over time, and this faster decrease was, in turn, associated with more externalizing problems. This accelerated decrease in connectivity could potentially reflect an accelerated development of this brain circuit in response to early stress.

“The present study provided evidence that harsh parenting in early childhood is prospectively associated with both externalizing behavior and the developmental trajectories of functional connectivity profiles of the amygdala, with some support for sex differences at the behavioral and neurocircuitry levels,” the researchers concluded.

The study, “Harsh parenting, amygdala functional connectivity changes across childhood, and behavioral problems,” was authored by Yuna Koyama, Henning Tiemeier, Pei Huang, Shi Yu Chan, Mioko Sudo, Yena Kyeong, Michael Meane, Peipei Setoh, and Ai Peng Tan.