Living happily ever after: longitudinal insights into enduring mental health and wellbeing

PURPOSE: Enduring Mental Health (EMH) reflects maintaining good psychological functioning without developing mental health problems. Estimates of the proportion of individuals who have EMH vary widely. We investigated EMH across the lifespan, defined not only as absence of mental health problems, but also as consistent presence of high wellbeing. To explore how defining EMH affects the phenotype, we included both stricter and broader lenient thresholds for mental health problems and low wellbeing. METHODS: Data came from 16,030 Netherlands Twin Register participants (35% male; mean birth year 1970) with ≥ 4 assessments over 8-20 years. For each EMH definition, preregistered analyses included computation of prevalence, genetic and environmental influences using twin modeling, and phenotypic and genetic correlates including education, personality, social factors and polygenic scores. RESULTS: Threshold choice for low mental health strongly affected prevalence of EMH: 71% (absence of problems),93% (high wellbeing), and 71% (combined) for stricter thresholds versus 42%, 82%, and 42% for lenient thresholds of low mental health. Heritability (46-61%) and patterns of associations were similar across definitions. Optimism, social support, and good self-rated health were positively associated with EMH (OR = 1.5-2.9), while neuroticism, loneliness, and stress lowered the likelihood (OR = 0.3-0.8). CONCLUSION: Defining EMH using different thresholds for mental health changed prevalence estimates, whereas heritability and correlates were broadly similar across definitions. Threshold choice is important for estimating how common EMH is, while the consistent pattern of correlates suggest shared underlying mechanisms that can inform prevention to help individuals maintain mental health.