Living Happily Ever After: Longitudinal Insights into Enduring Mental Health and Wellbeing

Enduring Mental Health (EMH) has been defined as 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 prevalence, we included both stricter and broader lenient thresholds for mental health problems and low wellbeing.Data came from 16,030 participants (35.2% male; average birth year 1970) from the longitudinal Netherlands Twin Register, who completed ≥4 assessments of mental health and/or wellbeing 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 genetic predispositions for mental health outcomes.As expected, the choice of threshold had a substantial impact on EMH prevalence estimates, 71% for absence of problems and 93% for high wellbeing when applying stricter thresholds for mental health compared to lenient thresholds, 42% and 82%, respectively. Heritability estimates (46-61%) and patterns of associations for EMH were similar across the different mental health thresholds. Protective factors included optimism, social support, and good self-rated health (OR= 1.50-2.86), while neuroticism, loneliness, and perceived stress were risk factors (OR=0.31-0.84).We show the importance of defining EMH as both the absence of problems and the presence of wellbeing. While prevalence varied depending on threshold and definition used, the consistent genetic and psychosocial correlates for different definitions of EMH suggest stable underlying mechanisms that can inform prevention to help individuals maintain mental health.