Stability of mental abilities and physical growth from 6 months to 65 years: Findings from the Zurich Longitudinal Studies

Mental abilities and physical growth are important determinants of health across the lifespan. Here, the stability of these traits was assessed from 6 months to 65 years of age to investigate periods of stability and malleability. Mental abilities, height, and weight were assessed at 11 time-points in participants of the Zurich Longitudinal Studies. Individuals with more than three missing data points per trait across the 11 assessment time-points (i.e., more than approx. 25% missing data) were excluded from further analyses (final N = 281). Bivariate cross-time correlations showed that the stability of mental abilities was low in infancy and gradually increased. The stability of growth measures was uniform across development, with height being highly stable and weight moderately so. When a latent model was used, the overall stability of mental abilities approached that of weight. The findings indicate that stability and malleability across development differ between mental abilities and growth measures. This requires consideration in interventions targeting these traits as facilitators for improving health outcomes.