Barbara Geller, MD reviewing Walhovd KB et al. Proc Natl Acad Sci U S A 2016 Jul 18.

Across the lifespan, trajectories of brain size and cognition followed parallel pathways, and the highest trajectories were associated with greater birthweight and better parental education.

Relationships between cognition and environmental factors in specific age groups are often studied (e.g., lower Alzheimer disease risk with higher education). But less has been known about relationships between intellectual ability and brain development across the lifespan. Investigators in Norway examined this issue in 974 individuals aged 4 to 88 years who underwent magnetic resonance imaging and tests of general cognitive ability (GCA; age-specific Wechsler IQ tests); most underwent rescanning 2 years later (1633 observations).

First, in a subsample of 502 children (ages, 4–12 years), investigators located brain cortical areas strongly associated with GCA. Within this defined region of interest (ROI), studies have previously shown that cortical area had a higher correlation with GCA than cortical volume or cortical surface measurements.

Trajectories of cortical area and GCA ran parallel and were stable over time, with larger cortical surface areas and higher GCA occurring in those with larger birthweights and higher parental education. Numerous other prenatal and neonatal variables were not significant. Analysis of independent study data on male twins confirmed genetic and environmental contributions to trajectory patterns. In an assessment of genetic factors in the population-level study, height (which is genetically determined) was added to data analyses, but did not alter the findings.

CITATION(S):

Walhovd KB et al. Neurodevelopmental origins of lifespan changes in brain and cognition. Proc Natl Acad Sci U S A 2016 Jul 18; [e-pub].

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