A new study analysing long-running US survey data suggests that family-level cognitive ability may be linked to how healthy mothers are in midlife. Researchers found that mothers whose children performed better in mathematics and reading tended to report better physical and mental health, while poorer cognitive performance in children was associated with larger declines in mothers’ physical health between ages 40 and 50. The research has been published in the journal Intelligence.
Intelligence is described by the authors as the general capacity to learn, reason, solve problems, understand complex information and adapt to new situations. It has long been connected with a wide range of health outcomes, with higher cognitive ability typically linked to better physical and mental health, and a lower risk of death. These associations have helped fuel the field of cognitive epidemiology, which examines how cognitive abilities relate to health across the lifespan.
The researchers emphasise that the relationship between intelligence and health may begin early in life and be bidirectional. Parental health can influence children’s cognitive development, while a child’s cognitive performance can, in turn, affect parental well-being. As a result, the study emphasises the family as an important unit for understanding how cognitive abilities relate to health.
Lead author Linda Wänström and colleagues set out to explore the link between family intelligence and maternal health, focusing on how the intelligence of children relates to the health of their mothers.
The team used data from the National Longitudinal Survey of Youth 1979 (NLSY79), a long-running survey of thousands of US adolescents and young adults. The NLSY Children (NLSYC) dataset contains all biological children of the NLSY79 mothers, totalling more than 11,500 individuals, with participants followed every two years since 1986. About half of the children were male.
Children in the NLSYC completed the Peabody Individual Achievement Test (PIAT) in mathematics, reading recognition and reading comprehension at up to five assessments each, across ages 5 to 15 between 1986 and 2014.
Health assessments of the mothers were conducted as they reached ages 40 and 50, beginning in 1998 and 2008 respectively. These included self-reported measures of physical and mental health, plus a depression scale. In addition, the mothers underwent an intelligence assessment in their own youth, between ages 15 and 23, using the Armed Forces Qualifying Test as a proxy for intelligence.
The study found that, on average, mothers experienced a rise in depression symptoms between 40 and 50 and a decline in physical health scores. Meanwhile, the children’s math and reading scores rose as they grew older.
Mothers whose children achieved stronger math and reading scores tended to report better physical and mental health. Conversely, low levels of math and reading comprehension in children were linked to larger declines in mothers’ physical health between ages 40 and 50.
“The results indicated that family-level intelligence is positively related to maternal health at middle-age,” the study authors wrote.
The authors also discuss a notion of a “Flynn effect transfer” within families—the idea that higher cognitive levels and gains, potentially from later motherhood and later cohorts, may relate to better maternal health outcomes in midlife, a topic they suggest could be explored in future work.
While the study contributes to understanding the links between health and cognitive abilities, it notes a methodological caveat: the analysis did not use a dedicated intelligence test, instead relying on achievement tests as proxy indicators for intelligence. The authors acknowledge that, although achievement scores tend to correlate highly with intelligence, this approach is not universally accepted among researchers.
The paper, “Family-level intelligence and maternal health: A cross-cohort, cross-generational longitudinal study using the NLSY,” is authored by Linda Wänström, Patrick O’Keefe, Graciela Muniz-Terrera, Stacey Voll, Frank D. Mann, Sean Clouston, Scott Hofer and Joseph L. Rodgers.
