Childhood social class as a moderator of late-life cognitive abilities

Introduction: Genetic influences on cognitive ability vary across socioeconomic groups, where the heritability of cognitive ability is attenuated in poor childhood environments compared to more advantaged environments where... [ view full abstract ]

Introduction: Genetic influences on cognitive ability vary across socioeconomic groups, where the heritability of cognitive ability is attenuated in poor childhood environments compared to more advantaged environments where the genetic influences seems to have a greater influence [1]. The objective of this study was to investigate this moderation by socioeconomic environment on cognitive ability persist into late life. We investigated if increase in genetic variance with increasing social class is maintained in advancing age, as the distance from childhood and education increases.

Methods: We used data from the Swedish Adoption/Twin Study of Aging (SATSA), consisting of 859 individuals (Twins Reared Apart=425 (200 pairs) and Twins Reared Together=434 (220 pairs)) aged 50-96, with cognitive data from up to 9 in-person testing occasions spanning over 28 years. We utilized data from all time points using the intercept at the centering age 65. Cognitive ability was measured via a principal component score that covered four domains: verbal, fluid, memory and perceptual speed abilities. A general ability score was derived through principal component analysis. Childhood social class (parental occupation) and education were self-reported. Models with childhood social class or education moderating A, C, and E for cognitive ability were applied to both the total sample and separately to the TRT.

Results: The results from the moderator models for both childhood social class and own education showed similar patterns. C increased with higher socioeconomic measures at the same time as a relative decrease in A for general ability, verbal and spatial. Moderation by childhood social class was statistically significant only for verbal abilities and by education for general ability and verbal abilities. Moderation by childhood social class differs between childhood and late-life cognitive abilities. We will be replicating these findings on other samples within IGEMS.

1. Turkheimer, E., et al., Socioeconomic status modifies heritability of IQ in young children. Psychol Sci, 2003. 14(6): p. 623-8.