Research Illustrates Socioeconomic Disparities in Adolescent Reward Systems

MIT neuroscientists conducted a study on the impact of socioeconomic conditions on the brain’s sensitivity to rewarding experiences, a key factor in motivation and attention. The research focused on 12 to 14-year-olds with varying socioeconomic status (SES) and found that children from lower SES backgrounds exhibited lower sensitivity to rewards compared to their more affluent counterparts. 

The study utilized functional magnetic resonance imaging (fMRI) to measure brain activity as the children engaged in a guessing game where they earned additional money for correct guesses. The results showed that when children from higher SES backgrounds guessed correctly, a brain region known as the striatum, associated with reward, exhibited significantly more activity compared to children from lower SES backgrounds. 

Behavioral differences also accompanied these neural findings, indicating that participants from lower and higher SES backgrounds responded differently to correct guesses. The study suggests that lower SES circumstances may lead the brain to adapt to the environment by reducing its response to rewards, which are often less abundant in economically disadvantaged environments. 

John Gabrieli, the Grover Hermann Professor of Health Sciences and Technology, a professor of brain and cognitive sciences, and a member of MIT’s McGovern Institute for Brain Research, explained that individuals in highly resourced environments with abundant rewards have brains tuned in a specific way. On the other hand, those in environments with scarce rewards may exhibit less responsiveness to rewards due to the inconsistent availability of rewards in their environment. 

Gabrieli, along with Rachel Romeo, a former MIT postdoc now an assistant professor at the University of Maryland, were the senior authors of the study. The lead author, MIT postdoc Alexandra Decker, conducted the research, and the findings were published in the Journal of Neuroscience. 

Previous research has demonstrated that children from lower SES backgrounds tend to perform worse on tests related to attention and memory, and they are more susceptible to depression and anxiety. However, few studies have explored the potential association between SES and reward sensitivity until this MIT study. 

The researchers focused on the striatum, a brain region crucial for reward response and decision-making. Studies in both humans and animal models have shown that the striatum becomes highly active during rewarding experiences. The goal was to investigate the connection between reward sensitivity, the striatum, and socioeconomic status. 

The study involved recruiting over 100 adolescents from diverse SES backgrounds, with SES measured by household income and parents’ education levels. Each participant underwent fMRI scanning while playing a guessing game.

The game involved predicting whether the next number in a series would be greater or less than 5, with monetary rewards tied to correct guesses. The game was designed to manipulate reward availability, allowing the researchers to ensure that each participant experienced periods of abundant and scarce rewards. In the end, all participants received the same amount of money, in addition to a stipend for participating in the study. 

The results highlighted a correlation between SES and the striatum’s response to rewards. Children from lower SES backgrounds showed less striatal activation in response to rewards compared to those from higher SES backgrounds. This aligns with the idea that individuals from lower SES backgrounds may develop a less responsive reward system due to the inconsistent availability of rewards in their environment. 

The study sheds light on the potential neural mechanisms underlying the impact of socioeconomic conditions on motivation and attention. Understanding how the brain adapts to different environments can contribute to efforts aimed at addressing disparities in cognitive and emotional well-being associated with socioeconomic factors. 

Journal Reference  

Alexandra L. Decker et al, Striatal and Behavioral Responses to Reward Vary by Socioeconomic Status in Adolescents, Journal of Neuroscience (2024). DOI: 10.1523/JNEUROSCI.1633-23.2023.