Chapter 7: Development of the Brain and Nervous System
Exposure to adversity, especially early in childhood, is known to have long-lasting consequences on brain development and subsequent behavioral outcomes. For instance, research has shown that experiencing poverty during early childhood is associated with lower academic performance, educational attainment, and adult earnings (Duncan et al., 1998, 2010). Relatedly, children whose families have higher family income tend to be associated with higher language, memory, social-emotional processing, and self-regulation skills (Noble et al., 2005, 2007). In terms of shaping the brain, higher family income has been associated with expanded surface area in brain regions involved in language and executive functioning (Noble et al., 2015). Ultimately, while it’s clear that poverty is closely associated with negative effects on the brain and behavior, much remains unknown about how these effects on neural development emerge over time. One landmark study, the Baby’s First Years project, is carrying out the first randomized control trial of poverty reduction in early childhood and assessing how poverty reduction influences children’s brain development over time (Noble et al., 2021). As part of the study, 1,000 diverse low-income mothers in four metropolitan areas in the United States were randomly assigned to receive either a large ($333) or nominal ($20) monthly cash gift. By measuring infants’ electrical brain activity one year into the poverty-reduction intervention, the researchers showed that infants whose mothers were randomized at the time of birth to receive a large monthly cash gift showed greater electrical brain activity in regions associated with better language, cognitive, and social-emotional outcomes in later childhood. Ultimately, brain development during early childhood is responsive to their lived experiences, and as such, scientists are beginning to further explore how exposure to adversity may influence brain organization and how this may be associated with behavioral outcomes.
Given the extensive array of social, emotional, and cognitive changes that take place during adolescence, the Adolescent Brain Cognitive Development (ABCD) study was launched as the largest long-term study of brain development and child health in the United States. Twenty-one research sites across the country are following over 11,000 children for ten years, beginning at age nine and continuing through adolescence into early adulthood and tracking their biological and behavioral development (Luciana et al., 2018). By conducting assessments on brain structure and function, neurocognition, physical and mental health, social and emotional function, and culture and environment, the ABCD study will provide a comprehensive window into how this sensitive period of development unfolds in the brain and how that may lead to differences in behavior from childhood through young adulthood. The rich data from this massive ABCD study will provide key insights into understanding important topics, such as links between family environment, children’s behavior problems, and brain structure (Gong et al., 2021), effects of cannabis use on psychopathology (Paul et al., 2021), and links between screen time, academic performance, and mental health (Paulich et al., 2021).