Are trajectories of social isolation from childhood to mid-adulthood associated with adult depression or suicide outcomes

Purpose Social isolation has been shown to have negative effects on mental health outcomes though little is known about trajectories across the life course. We examined the relationship between trajectory groups and selected mental health outcomes in mid-adulthood.Methods We previously created a typology of social isolation based on onset during the life course and persistence into adulthood, using group-based trajectory analysis of longitudinal data from a New Zealand birth cohort. The typology comprises four groups: 'never-isolated', 'adult-only', 'child-only', and 'persistent (child-adult) isolation'. We undertook logistic regression analyses of three mental health outcomes with trajectory group as the predictor, adjusting for sex and a range of familial and child-behavioural factors.Results Lifetime suicide attempt, and depression and suicide ideation in mid-adulthood were each associated with adult-only but not child-only social isolation. Depression in mid-adulthood was also associated with persistent child-adult social isolation.Conclusion Although our findings are associational and not causal, they indicate that interrupting persistent social isolation may help to prevent adult depression whereas halting adult social isolation may ameliorate both depression and suicide outcomes.