The nature of the relation between mental wellbeing and illbeing

Research on mental health has traditionally separated the study of illbeing—including clinically defined mental and behavioural disorders and subthreshold problems—from the study of wellbeing—which encompasses factors such as life satisfaction and positive affect. While previous reviews of studies primarily employing self-report scales indicate that illbeing and wellbeing are distinct yet interconnected constructs, a deeper examination of their relationship is lacking. In this Perspective, we synthesize genetic, biological, developmental, psychosocial, societal, cultural, and clinical research on illbeing and wellbeing. Our review reveals substantial genetic overlap and similar biological underpinnings for illbeing and wellbeing. In contrast, environmental factors and societal changes often exert divergent influences. We propose a differentiated multidisciplinary framework in which the shared and unique determinants, predictors, mechanisms, and consequences of mental illbeing and wellbeing vary across levels of analysis, offering a more nuanced understanding of the interconnections.