In a landmark international study, researchers have drawn on genetic data from nearly one million individuals to examine the links between socioeconomic status (SES) and brain health. The team analysed how four key indicators — occupation, income, education, and social deprivation — correlate with genetic variation, revealing that a substantial portion of the genetic influences on these traits are shared. Specifically, around 75 per cent of the genetic effects associated with each of the four SES measures overlapped, suggesting the presence of a common genetic factor influencing social and economic positioning. This unified SES signal allowed researchers to assess shared social influences across the individual, household, and broader community.
This genetic factor of SES was studied in a cohort of 947,466 people using a genome-wide association study (GWAS) method. GWAS allows scientists to identify regions statistically associated with particular traits in the human genome. The team identified 554 specific genomic regions tied to SES through this technique. However, it is essential to note that these findings do not suggest that SES is genetically determined in a deterministic sense. Instead, the data reflect patterns in how specific genetic variants may correlate with social outcomes when embedded within broader environmental and societal contexts.
To better understand whether and how SES impacts brain health, the researchers then turned to a separate group of approximately 40,000 individuals who had undergone brain imaging. Their focus was on white matter hyperintensities — small lesions in the brain that increase with age and are linked to poorer thinking skills heightened dementia risk, and general declines in brain function. They found that people with higher SES tended to have fewer white matter hyperintensities, suggesting that socioeconomic advantage may offer some protection against age-related brain changes. This indicates a likely causal relationship in which SES influences neurobiological outcomes, not merely correlates with them.
Despite the genetic associations identified, the study was careful to underscore genetics’s modest role in explaining SES differences. Common genetic variation accounted for only about nine per cent of the variation in socioeconomic status among the study population. The vast majority of social standing, income, and education differences are shaped by environmental factors — including social policies, access to education, systemic inequalities, and even chance events. In this context, genes may set the stage, but the play is directed by the conditions in which people live, learn, and work.
Dr David Hill, lead author and MRC Research Fellow at the University of Edinburgh’s School of Philosophy, Psychology and Language Sciences, emphasised the significance of identifying a shared genetic factor for SES. According to Hill, this composite measure enabled a more comprehensive understanding of the socioeconomic forces that influence brain structure. “By using this common socioeconomic status factor,” he said, “we were able to capture aspects of socioeconomic status shared between the individual, the household, and the area in which one lives. This enabled us to better identify the causal effects of socioeconomic status on brain structure.”
Co-author Dr Charley Xia offered a vital clarification: the findings should not be misconstrued as evidence that brain health is genetically predetermined. “Studies examining traits such as socioeconomic status using genetic data can be easily conflated,” Xia warned. “We have not shown that brain health is genetically determined – rather that through genetic data we were able to identify socioeconomic status as a modifiable environmental influence on brain health in older age.” Overall, the research illustrates the potential of combining genetic and environmental data to understand better how societal inequalities might translate into long-term differences in brain health and cognitive ageing.
More information: David Hill et al, Deciphering the influence of socioeconomic status on brain structure: insights from Mendelian randomization, Molecular Psychiatry. DOI: 10.1038/s41380-025-03047-4
Journal information: Molecular Psychiatry Provided by University of Edinburgh
