Massive study finds strong correlation between “early affluence” and “faster cognitive drop” in old age
- Survivor bias: it may be that poor people who experience loss of verbal fluency die younger, so if you experience verbal fluency loss but don't die, you're probably rich.
Sampling bias: it may be that poorer people were less likely to be included in the SHARE study cohort.
The study was based on six waves of the Survey of Health, Aging, and Retirement in Europe (SHARE). Researchers looked at 24,066 people at baseline who were ages 50 to 96 years; 56% of the sample was female and people suspected to have dementia at baseline were excluded. Data were collected at baseline (2004) and every 2 years after that. Childhood socioeconomic status was based on four indicators at age 10: the main breadwinner's occupational position, the number of books at home, overcrowding, and housing quality. The researchers examined trajectories of two cognitive functions, delayed recall (assessed by a 10-word delayed recall test) and verbal fluency (assessed by an animal naming test). Over the study period, the average number of observations for each participant was 2.76 for delayed recall and 3.29 for verbal fluency. Overall, the more advantaged the childhood environment was, the higher the levels of delayed recall and verbal fluency were in later life. Cognitive decline was related to childhood affluence only for verbal fluency, not for delayed recall: people with a more advantaged childhood experienced more decline in verbal fluency than people with the most disadvantaged childhood socioeconomic conditions. Associations between childhood environment and level of functioning were partly mediated by socioeconomic conditions throughout the life course, but not by current levels of physical activity, depressive symptoms, or having a partner.
Advantaged socioeconomic conditions in childhood are associated with higher cognitive functioning but stronger cognitive decline in older age [ Marja J. Aartsen, Boris Cheval, Stefan Sieber, Bernadette W. Van der Linden, Rainer Gabriel, Delphine S. Courvoisier, Idris Guessous, Claudine Burton-Jeangros, David Blane, Andreas Ihle, Matthias Kliegel, and Stéphane Cullati/PNAS] Early Affluence Tied to Faster Cognitive Drop Late in Life [Judy George/Medpagetoday]