Age-related enhancements in positive emotionality across the lifespan: structural equation modelling of brain and behaviour

Ageing is associated with a bias in attention and memories towards positive and away from negative emotional content. In addition, emotion regulation appears to improve with age, despite concomitant widespread cognitive decline coupled with gray matter volume loss in cortical and subcortical regions thought to sub-serve emotion regulation. Here, we address this emotion-aging paradox using the behavioural data of an emotion regulation task from a population derived sample (CamCAN) and utilise Structural Equation Modelling together with multivariate analysis of structural MRI images of the same sample to investigate brain-behaviour relationships. In a series of measurement models, we show the relationship between age and emotionality is best explained by a four-factor model, compared to single and hierarchical factor models. These four latent factors are interpreted as Basal Negative Affect, Positive Reactivity, Negative Reactivity and Positive Regulation (upregulating positive emotion to negative content). Increasing age uniquely contributes to increased Basal Negative Affect, Positive Reactivity and Positive Regulation, but not Negative Reactivity. Furthermore, we show gray-matter volumes, namely in the bilateral frontal operculum, medial frontal gyrus, bilateral hippocampal complex, bilateral middle temporal gyri and bilateral angular gyrus, are distinctly related to these four latent factors. Finally, we show that a subset of these brain-behaviour relationships remain significant when accounting for age and demographic data. Our results support the notion of an age-related increase in basal emotionality together with a positivity bias and are interpreted in the context of the Socioemotional Selectivity Theory of improved emotion regulation in older age.