Characterising mental wellbeing and associations with subcortical grey matter volume at short intervals in early adolescence

This temporally rich, longitudinal study of early adolescents (N = 88, 277 datasets, 12–13 years) investigated the relationship between bilateral subcortical grey matter volume (GMV) in the hippocampus, amygdala, accumbens-area, caudate, putamen and pallidum with self-reported mental wellbeing at four timepoints, across 12 months. Generalised Estimating Equations (GEE) revealed (1) higher ‘total wellbeing’ was associated with smaller left caudate and larger left accumbens-area; (2) higher eudaimonic wellbeing was associated with smaller left caudate and larger right caudate; and (3) higher hedonic wellbeing was associated with larger left accumbens-area. Further analyses and plots highlighted different associations between GMV and wellbeing for adolescents who consistently experienced ‘moderate-to-flourishing’ wellbeing (n = 63, 201 datasets), compared with those who experienced ‘languishing’ wellbeing at any timepoint (n = 25, 76 datasets). These findings demonstrate several associations between subcortical GMV and measures of wellbeing, at short intervals in early adolescence. Taken together, sub-types of wellbeing appear uniquely associated with specific subcortical regions; and there may be a distinct neurobiological and wellbeing profile for adolescents who experience poorer wellbeing over the course of their first year(s) of secondary school. This study implicates the bilateral caudate and left accumbens-area as important targets for future research into the mental wellbeing of adolescents. •Adolescent wellbeing measures may elucidate understandings of brain development.•Wellbeing associated with bilateral caudate and left accumbens grey matter volume.•Eudaimonic and hedonic wellbeing differently associated with grey matter regions.•Short-interval longitudinal neuroimaging reveals impacts of wellbeing fluctuations.•‘Languishing’ adolescents may have a distinct neurobiological and wellbeing profile.