Do brain cortical thickness differ according to income ? Psychological Science.June, 2015

15 06 2015

Educational achievement is highly correlated with socio economic status. The difference in academic achievement between students from higher and lower income groups  (income achievement gap) is increasing in many countries. There are various ( social, psychological, biological) reasons for this. Are there neuroanatomical differences between higher and lower income children ? Do these differences explain the income achievement gap?

Allyson P. Mackey and team of researchers from USA related cortical structure parameters ( cortical grey and white matter volumes, cortical surface area)  to family income and performance on standardized tests of academic skills. Eligibility for free/ reduced price lunch at school was the criterion for classifying as poor SES. Participants, 58 school children ( 15 yrs age on average) participated in this study. They completed Massachusetts Comprehensive Assessment System (MCAS) for academic performance measure.All underwent MRI to measure the cortical parameters.


Academic performance scores were significantly lower in lower income group.Cortical gray-matter volume was significantly greater in the higher-income group than in the lower-income group. Cortical thickness in all lobes of the brain was greater in students from higher-income than lower-income backgrounds. Greater cortical thickness, particularly in temporal and occipital lobes, was associated with better test performance. Cortical white-matter volume and total cortical surface area did not differ significantly between groups.

It is possible that these differences are due to less gray-matter formation early in development  or could be due to accelerated thinning. Higher levels of stress and less enrichment in the environment may have influenced brain development.

It needs to be highlighted that a thicker cortex is not inherently better. relationship between cortical thickness and cognitive performance is still unclear. Educational interventions in lower income children have proven to enhance performance as well as neural connectivity.

comments: It is well established that income and SES play a crucial role in academic achievement. Growing body of research indicate that brain suffer from inequality and poverty in many different ways.

Summary of the article:

Neuroanatomical correlates of the income-achievement gap. Mackey AP, Finn AS, Leonard JA, Jacoby-Senghor DS, West MR, Gabrieli CF, Gabrieli JD. Psychol Sci. 2015 Jun;26(6):925-33

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