New research published in Developmental Cognitive Neuroscience sheds light on the relationship between neighborhood disadvantage and alterations in brain structure during adolescence. The findings indicate that neighborhood disadvantage is associated with deviations from typical brain developmental trajectories, but that heightened self-regulation buffers the effects of neighborhood disadvantage on neurodevelopment.
“A large portion of kids live in poor neighborhoods. Poor neighborhoods are areas where people generally have lower levels of income, employment, and education. Growing up in a poor neighborhood can be a source of stress for children, and is sometimes associated with cognitive problems and mental health issues in young people,” explained lead researcher Divyangana Rakesh, a PhD candidate at the University of Melbourne.
“We don’t exactly understand these links yet, but it is thought that one way neighborhoods impact outcomes could be via its impact on brain development. This is why we wanted to study the effects of neighborhood disadvantage on brain development in adolescence, in the hope that these investigations will help shed light on how neighborhood disadvantage gets under the skin and contributes to poor outcomes in some children and adolescents. We also wanted to study if there are any psychological or environmental factors (like providing children with positive parenting or even their own temperament) that can buffer the negative effects of living in a poor neighborhood.
To examine the relationship between neighborhood disadvantage and structural neurodevelopment during adolescence, the researchers used machine learning models to compute an individual’s brain age based on neuroimaging data. The Philadelphia Neurodevelopmental Cohort dataset, which contained structural magnetic resonance imaging (MRI) scan data for 1,313 youths, was used to establish a normative model of brain age. This model was then applied to data from the Orygen Adolescent Development Study, longitudinal research in which adolescents completed three structural MRI scans over the course of several years.
The researchers were particularly interested in the difference between a participant’s predicted brain age and their chronological age. They found evidence that different levels of neighborhood disadvantage were associated with different levels of brain maturation, and that a temperamental characteristic known as effortful control moderated this relationship.
The findings indicate that “that living in a disadvantaged neighborhood is associated in changes in way the brain developed from early to late adolescence, but that these changes are different in adolescents with high versus low levels of a temperament dimension called ‘effortful control’ (which is the ability to utilize attentional resources to better regulate emotions and inhibit inappropriate behavioral responses),” Rakesh told PsyPost.
“Our results essentially showed the children who grew up in disadvantaged neighborhoods had brains that looked older than was typical for their age during early adolescence, but that this gap slowly reduced with age by late adolescence. What’s more, these associations held true even when we accounted for household socioeconomic status and other adversities (such as childhood abuse and neglect), which suggests that neighborhood disadvantage has a unique role to play in brain development.”
“In addition, individuals from disadvantaged neighborhoods who had low effortful control demonstrated delayed brain development by late adolescence – the same pattern was not evident in their more advantaged peers or in disadvantaged adolescents with high effortful control,” Rakesh explained. “Further, we found that while positive parenting behavior did not buffer the effects of neighborhood disadvantage on neurodevelopment, it was independently associated with brain development trajectories, whereby adolescents who experience low positive parenting had accelerated development during early adolescence, which was followed by a steep decline resulting in delayed brain development by late adolescence.
“In sum, brain development is a complex and prolonged process, and can be influenced by both environmental and psychological factors, such as neighborhood disadvantage, temperament, and parenting behavior.”
The research provides important new information about the interplay between neighborhood disadvantage, psychological factors, and neurodevelopment in adolescence. But Rakesh explained some caveats of the study:
“One major caveat is the amount of individual variability there is in people, which is often left unaddressed in such research,” she said. “What we mean by that is that there are many individuals from disadvantaged neighborhoods that do not show brain alterations. But this sort of individual variability is lost in the kinds of analyses we do (where we examine averages of groups of people rather than looking at individual data points). It is therefore important to account for this individual variability in our studies, and also examine what makes certain individuals resilient.”
“Second, we did not find that these brain changes were associated with mental health outcomes. That means that our observed brain alterations did not act as mechanisms that transmitted the effects of neighborhood disadvantage and contributed to poor mental health in the adolescents. It is therefore possible that these alterations are in fact adaptations that represent resilience mechanisms and/or are associated with positive functioning. However, it is hard to answer this question without knowledge of the full development trajectory. More research with extended longitudinal designs that follow people from childhood into adulthood is needed.”
The study, “Neighborhood disadvantage and longitudinal brain-predicted-age trajectory during adolescence“, was authored by Divyangana Rakesh, Vanessa Cropley, Andrew Zalesky, Nandita Vijayakumar, Nicholas B. Allen, and Sarah Whittle.