The heritability of mental health and wellbeing defined using COMPAS-W, a new composite measure of wellbeing
Introduction
Psychiatric research has been driven by an illness ideology; a focus on identifying risk markers for mental illness, their underlying mechanisms and appropriate treatment strategies. In comparison, much less focus has been given to mental health and wellbeing and ways to promote it. This is because of the common misconception that the absence of mental illness is the equivalent to mental health (Keyes, 2005, Slade, 2010). However, only one quarter of the factors that define mental health and mental illness are shared in common (Kendler et al., 2011; Keyes, 2005, Slade, 2010). This suggests that the genetic, environmental and biological markers that underlie mental illness differ substantially from those that underlie mental health. Accordingly we are witnessing a paradigm shift towards mental health or wellbeing (Maddux, 2008), in which the focus is on defining optimal wellbeing and on the emerging science of resilience (Russo et al., 2012, Southwick and Charney, 2012).
Existing definitions of wellbeing have tended to emphasize concepts of subjective wellbeing, psychological wellbeing, or their combination. “Subjective wellbeing” reflects hedonia (Andrews and Withey, 1976, Bradburn and Caplovitz, 1965, Diener et al., 1995, Diener et al., 1999, Wilson, 1967) and has been quantified by measures of positive and negative affect (Diener et al., 2010) and satisfaction with life (Diener et al., 1985). “Psychological wellbeing” is tied to the concept of eudaimonia, which is focused on the development of human potential (Broadie and Rowe, 2002, Ryff, 1989). For instance, Ryff (1989) defined psychological wellbeing as a composition of autonomy, positive relations with others, purpose in life, self-acceptance, environmental mastery and personal growth, which was later quantified by the Ryff Scales of Psychological Well-Being (Ryff and Keyes, 1995). Only recently has a distinction been drawn between subjective and psychological wellbeing (Ryff and Singer, 1998) whereas early theorists never made such a distinction (Argyle, 1987, Brickman and Campbell, 1971, Wilson, 1967). There is much to be gained in the empirical study of both the subjective and psychological aspects of wellbeing as demonstrated by accumulating evidence from composite indices of wellbeing (e.g., the Mental Health Continuum, MHC-LF; Keyes, 2007); both constructs are strongly associated with each other with factor analytic studies showing shared variance of 49–74% (Keyes et al., 2002, Waterman, 1993). Other studies suggest that psychological wellbeing directly influences subjective wellbeing (Kasser and Ryan, 1996, Ryan and Deci, 2001, Sheldon, 2002). The direction of causation of these effects however is unclear, as many of these studies were correlational (Kashdan et al., 2008). In any case, each construct of wellbeing – whether correlated or causal – accounts for notable variance in wellbeing that would otherwise be unaccounted for if focusing only on one aspect (Kashdan et al., 2008). Recently, the PERMA theory of wellbeing, has attempted to encompasses aspects of both subjective wellbeing (positive emotion, meaning) and psychological wellbeing (engagement, relationships, accomplishment) (Seligman, 2011). This theory is a central component of The Positive Health Initiative (http://www.authentichappiness.sas.upenn.edu/) which aims to understand what defines wellbeing, how to determine its underlying neural circuitry and ways to promote it in the general population.
A composite measure of wellbeing may assist in assessing functional status in clinical and population cohorts. Functional correlates of wellbeing include enhanced cognitive functioning, increased marital satisfaction, and higher income and economic flourishing (Diener and Chan, 2011, Seligman, 2008). Wellbeing is also associated with physiological correlates of neuroendocrine level, cardiovascular and inflammatory activity (effect sizes of .38) (Brummett et al., 2009, Fredrickson and Levenson, 1998, Lyubomirsky et al., 2005, Steptoe et al., 2005). In addition, the measurement of wellbeing may be useful as a prognostic indicator of long-term health, disease outcomes and health behaviors. For instance, evidence from longitudinal studies shows that wellbeing is significantly predictive of longevity and ill-health (with effect sizes of .14–.18) (Diener and Chan, 2011, Howell et al., 2007, Lyubomirsky et al., 2005), as well as lower mortality in both healthy and diseased populations (Chida and Steptoe, 2008). In other studies, measures of wellbeing have been related to improved health behaviors such as non-smoking, physical exercise, healthy diets and use of sun protection (Grant et al., 2009).
In this study, we combine this theoretical background with a focus on heritability in order to address the questions of whether we have an innate disposition towards wellbeing or whether it is something we can modulate and elevate through personal life experience. Twin studies comparing monozygotic (MZ) to dizygotic (DZ) twins allow the contributions of genetics versus environment to wellbeing to be determined. In terms of hedonic (subjective) wellbeing, twin studies suggest additive genetics contributes 0% (Baker et al., 1992, Gatz et al., 1992) to 33% (Silberg et al., 1990) variance in positive affect, up to 46% in hedonia (Bogdan and Pizzagalli, 2009) and 48% for optimism (Schulman et al., 1993). In comparison, larger heritability estimates have been reported for eudaimonic (psychological) aspects of wellbeing. In young adult twins (23–24 years), additive genetics is reported to contribute from 37% variance in personal growth up to 64% in positive relations (Gigantesco et al., 2011), with estimates of 41% (autonomy), 47% (purpose in life), 58% (self-acceptance) and 62% (mastery) also reported (Gigantesco et al., 2011) for Ryff׳s psychological wellbeing scale. In contrast, in older twins (51–60 years), additive genetics contributes smaller estimates of 30% for locus of control (an element of mastery) and 41% for flow proneness (an element of engagement) (Mosing et al., 2012). Together, these findings suggest that some aspects of wellbeing may be more heritable than others; however they could also simply reflect differences between the twin cohorts. Each of these twin studies varied considerably in age of the cohort: all of the twin studies focusing on hedonia were based in twins across multiple decades, whereas the eudaimonic studies were within very specific age groups.
In this study, we first aim to derive a valid self-report measure of wellbeing that includes both hedonic and eudaimonic aspects of wellbeing and quantifies these individual differences in an overarching construct of wellbeing, along with sub-constructs that contribute to it, using a multifactorial approach. Our second aim is to evaluate the contributions of genes and environment to wellbeing (both hedonic and eudaimonic aspects), and how this may be shared or unique to specific subcomponents. In this study, we report the development and heritability of the COMPAS-W index of wellbeing in 1669 healthy adult twins ranging in age from 18–61 years from the TWIN-E study (Gatt et al., 2012).
Section snippets
Participants
Healthy same-sex monozygotic (MZ) and dizygotic (DZ) twins from the TWIN-E study (the Twin study in Wellbeing using Integrative Neuroscience of Emotion) conducted at the University of Sydney, Australia (see Gatt et al., 2012 for the complete study protocol) participated in this study. The study received approval from the Human Research Ethics Committees of the University of Sydney (03-2009/11430) and Flinders University (FCREC#08/09). All participants provided written informed consent prior to
Demographic characteristics
There were no significant differences between MZ and DZ twins, or twin 1 and 2 groups for age and education (p>0.05). There were proportionally more female DZ than male DZ twins, compared to MZ twins (p<0.001). Age, education and gender were included as covariates in analysis. Sample distribution information for the self-report measures between MZ and DZ twin pairs and twins 1 and 2 is presented in Table 1. No significant differences were found for the WHOQOL scales, SWLS, ERQ, ICI or NEO-FFI (p
Discussion
We validated a new 26-item measure of wellbeing called COMPAS-W, which provides an assessment of total Wellbeing as well as six subcomponents: Composure during stress, Own-worth, Mastery over environment, Positivity, Achievement and goal orientation and Satisfaction with physical, psychological health and social relationships. We tested the reliability of this scale in 846 first twins, and then independently confirmed it in 823 second twins. Good internal consistency and test–retest reliability
Author contributions
JMG developed the concept, conducted the literature search, developed the COMPAS-W scale, conducted the psychometric analyses, and wrote the first draft of the paper. KLOB assisted with the genetic modeling and data interpretation and development of the manuscript. PRS, RAB and LMW assisted with data interpretation and development of the manuscript.
Acknowledgments
This project was supported by an Australian Research Council (ARC) Linkage grant (LP0883621), with Brain Resource Ltd as industry partner. JMG was supported by an ARC Linkage Postdoctoral Fellowship (LP0883621) and a Westmead Charitable Trust Grant, and is currently supported by a National Health and Medical Research Council (NHMRC) Career Development Fellowship (APP1062495). KLOB is a PhD student working on the twin project. LMW was the chief investigator of the project and PRS was a partner
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