Wealthier men show higher metabolism in brain regions controlling reward and stress

An analysis of positron emission tomography data in Korea found that higher family income was associated with increased neural activity (estimated through increased glucose metabolism) in the caudate, putamen, anterior cingulate, hippocampus, and amygdala regions of the brain of middle-aged men. These areas of the brain are involved in reward processing and stress regulation. The paper was published in the European Journal of Neuroscience.

Socioeconomic status refers to a person’s position in society based on income, education, and social standing. It is a powerful predictor of many life outcomes. Individuals with higher socioeconomic status tend to have better physical and mental health and to live longer. Lower socioeconomic status is associated with higher rates of cardiovascular disease, diabetes, depression, anxiety, and psychotic disorders.

Cognitive abilities, intelligence, and academic achievement also tend to be higher in individuals with higher socioeconomic status. These effects are thought to arise partly through neurobiological pathways shaped by long-term social and environmental exposure. Research in animals shows that social hierarchy can alter neurotransmitter systems, influencing motivation, stress sensitivity, and vulnerability to addiction.

In humans, differences in socioeconomic status have been shown to produce differences in language development, learning opportunities, and responses to reward as early as childhood. Later in life, higher socioeconomic status contributes to cognitive reserve, affecting how well individuals maintain cognitive function despite aging or brain pathology.

Study author Kyoungjune Pak and his colleagues wanted to explore the associations between neural activity in middle adulthood, education, and family income. They note that a lot of research has focused on children, young people, and the elderly, but that the number of studies on middle-aged adults is relatively low. On the other hand, this period of life is particularly important, as accumulated experiences and exposures associated with socioeconomic status can have lasting effects on brain health.

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They analyzed positron emission tomography data of 233 healthy males who underwent a health check-up program at Samsung Changwon Hospital Health Promotion Center (in Changwon, South Korea) in 2013. Their average age was 43 years. Participants’ mean family income was 61,319 USD per year. On average, they completed 13–14 years of education. Study authors also included data from 232 men with missing socioeconomic status data for comparison to ensure the sample was representative.

In their analysis, study authors used positron emission tomography recordings of participants’ brains alongside data on family income and education level. They also used data on stress (collected using the Korean National Health and Nutrition Examination Survey), anxiety (the Beck Anxiety Inventory), and depression (the Centre for Epidemiologic Studies Depression Scale).

Results showed that individuals with higher family income tended to have a higher education level. Higher family income was also associated with increased glucose metabolism in the caudate, putamen, anterior cingulate, hippocampus, and amygdala regions of the brain.

This means that neural activity in these regions was higher in individuals with higher family income. These regions of the brain are involved in reward processing and stress regulation. Interestingly, education level was not associated with brain activity patterns.

“Family income and education level show differential associations with brain glucose metabolism in middle-aged males. Family income is associated with elevated brain glucose metabolism in regions involved in reward processing and stress regulation, suggesting a potential link between current socioeconomic resources and neural activity. However, these findings are cross-sectional and must be interpreted as associative rather than causal. Education level does not show a significant association with brain glucose metabolism,” the study authors concluded.

The study contributes to the scientific understanding of neural correlates of socioeconomic status. However, it is important to note that study participants were Korean middle-aged men, so it remains unknown how much these findings can be generalized to other demographic groups and other cultures.

The paper, “Family Income Is Associated With Regional Brain Glucose Metabolism in Middle-Aged Males,” was authored by Kyoungjune Pak, Seunghyeon Shin, Hyun-Yeol Nam, Keunyoung Kim, Jihyun Kim, Myung Jun Lee, and Ju Won Seok.