The psychosocial environment interpretation proposes that psychosocial factors are paramount in understanding the health effects of income inequality. Wilkinson has argued that income inequality affects health through perceptions of place in the social hierarchy based on relative position according to income.25
Such perceptions produce negative emotions such as shame and distrust that are translated “inside” the body into poorer health via psycho-neuro-endocrine mechanisms and stress induced behaviours such as smoking. Simultaneously, perceptions of relative position and the negative emotions they foster are translated “outside” the individual into antisocial behaviour, reduced civic participation, and less social capital and cohesion within the community. In this way, perceptions of social rank—indexed by relative income—have negative biological consequences for individuals and negative social consequences for how individuals interact. Perceptions of relative income thus link individual and social pathology.
Wilkinson's demonstration that absolute income was unrelated (r
=0.08) to health among developed countries has been important in staking a claim for this psychosocial theory of health inequalities.26
Figures and show the association between gross domestic product per person and life expectancy for 155 countries and for the 33 countries where gross domestic product was greater than $10
000—the cut-off used by Wilkinson.26
Our results, however, include data for all the countries above $10
000, not a selection of some countries in the Organisation for Economic Cooperation and Development as used by Wilkinson. The correlation between life expectancy and gross domestic product per person in the complete sample is r
=0.51 (P=0.003). Thus the association between absolute income and life expectancy among wealthier countries depends on which countries are included.
Gross domestic product per person in US dollars (adjusted for purchasing power parity) and life expectancy in 155 countries, circa 1993
Figure 2 Gross domestic product per person in all 33 countries with GDP/person greater than $10000
For 15 developed countries with comparable income inequality data, Lynch and colleagues showed that indicators of social capital, such as trust and belonging to and volunteering for community organisations, were all much more strongly related to gross domestic product per person than to income inequality.27
Diener and colleagues showed that absolute income was a better predictor of subjective wellbeing than relative income, and concluded that “exposure in natural settings to others who are better off will not automatically influence one's moods in a negative way.”28
In other analyses, social capital measured as trust and organisational membership mediated the cross sectional association between income inequality and mortality in US states.29
However, this association is difficult to interpret given that time series analyses of data from the same source show little decline in levels of trust, fairness, and helpfulness from the mid-1960s to 1994.30
The psychosocial hypothesis would lead to the expectation that these indicators of social capital should have deteriorated during this period of unprecedented increases in income inequality. In sum then, a broader consideration of relevant research raises questions about the evidence used to exclude absolute income and material conditions, and about the evidence in favour of a mainly psychosocial interpretation of health inequalities.
Areas of concern
We do not deny negative psychosocial consequences of income inequality, but we argue that interpretation of links between income inequality and health must begin with the structural causes of inequalities, and not just focus on perceptions of that inequality.27,31–35
In this regard, the psychosocial interpretation raises several areas of concern.
Firstly, it conflates the structural sources with the subjective consequences of inequality and reinforces the impression that the impact of psychosocial factors on health can be understood without reference to the material conditions that structure day to day experience.36
The structural, political-economic processes that generate inequality exist before their effects are experienced at the individual level.
Secondly, it underplays the ambiguous health consequences of tightknit social networks and greater social cohesion. Strong social networks can be coercive and can be sources of strain as well as support in relationships. In some contexts, network ties function to enhance health; in others they can be detrimental (S Kunitz, unpublished data).
Thirdly, a shallow definition of social cohesion or capital as informal social relations limits its potential relevance for public health.27
In health research, social cohesion and capital have been discussed as horizontal social relations, ignoring the crucial role that vertical, institutional social relations (political, economic, legal) play in structuring the environments in which informal relations play out.27,37,38
Finally, the psychosocial interpretation encourages understanding of psychosocial health effects in a vacuum. Although clearly not intended by its proponents, a decontextualised psychosocial approach can be appropriated for regressive political agendas, leading to claims that we lack the social cohesion of the past; that problems of poor and minority communities are really a result of deficits of strong social networks; and that local communities must solve their own problems. There has been little discussion of the possibility that focusing on what materially and politically disenfranchised communities can do for themselves may be akin to victim blaming at the community level that reinforces low expectations for structural change.39