Education and income show heterogeneous relationships to lifespan brain and cognitive differences across European and US cohorts
Walhovd KB., Fjell AM., Wang Y., Amlien IK., Mowinckel AM., Lindenberger U., Düzel S., Bartrés- Faz D., EBMEIER KP., Drevon CA., Baaré W., Ghisletta P., Johansen LB., Kievit RA., Henson RN., Madsen KS., Nyberg L., Harris J., Solé-Padullés C., Pudas S., Sørensen Ø., Westerhausen R., ZSOLDOS E., Nawijn L., Lyngstad TH., SURI S., Penninx B., Røgeberg OJ., Brandmaier AM.
Socio-economic status (SES) has been proposed to have facilitating and protective effects on brain and cognition. Here we show that relationships between SES, brain volumes and general cognitive ability differ significantly across European and US cohorts (4-97 years, N 500,000; 54,000 with brain imaging). Education was positively related to intracranial (ICV) and total brain gray matter (GM) volume. Income was related to ICV, but not GM. Relationships varied significantly across samples, and SES was more strongly related to brain and cognition in US than European cohorts. Differences in neuroanatomical volumes explained part of the SES-cognition relationships. SES was more strongly related to ICV than to GM, implying that SES-cognition relations in adulthood are less likely grounded in neuroprotective effects on GM volume in aging. Rather, a relationship may be established early in life. The findings underscore that SES has no uniform association with, or impact on, brain and cognition.