Social inequalities in depressive symptoms and physical functioning in the Whitehall II study: exploring a common cause explanation

Abstract

Study objective: This study investigated which risk factors might explain social inequalities in both depressive symptoms and physical functioning and whether a common set of risk factors might account for the association between depressive symptoms and physical functioning. Design: A longitudinal prospective occupational cohort study of female and male civil servants relating risk factors at baseline (phase 1: 1985-8) to employment grade gradients in depressive symptoms and physical functioning at follow up (phase 5: 1997-9). Analyses include the 7270 men and women who participated at phase 5. Setting: Whitehall II Study: 20 London based white collar civil service departments. Participants: Male and female civil servants, 35-55 years at baseline. Main results: Depressive symptoms were measured by a subscale of items from the 30 item General Health Questionnaire. Physical functioning was measured by a subscale of the SF-36. Employment grade was used as a measure of socioeconomic position as it reflects both income and status. The grade gradient in depressive symptoms was entirely explained by risk factors including work characteristics, material disadvantage, social supports, and health behaviours. These risk factors only partially explained the gradient in physical functioning. The correlation between depressive symptoms and physical functioning was reduced by adjustment for risk factors and baseline health status but not much of the association was explained by adjustment for risk factors. Among women, the association between depression and physical functioning was significantly stronger in the lower grades both before and after adjustment for risk factors and baseline health. For women, there was only a significant grade gradient in depressive symptoms among those reporting physical ill health. Conclusions: Some risk factors contribute jointly to the explanation of social inequalities in mental and physical health although their relative importance differs. Work is most important for inequalities in depressive symptoms in men, and work and material disadvantage are equally important in explaining inequalities in depressive symptoms in women while health behaviours are more important for explaining inequalities in physical functioning. These risk factors did not account for the association between mental health and physical health or the greater comorbidity seen in women of lower socioeconomic status. The risk of secondary psychological distress among those with physical ill health is greater in the low employment grades. Many studies have shown gradients in physical ill health and mortality by socioeconomic position.

Associations of C-reactive protein and interleukin-6 with cognitive symptoms of depression: 12-year follow-up of the Whitehall II study

“…Yet, the scale was reliable, it was factorially derived from a validated questionnaire within the Whitehall II study (Stansfeld, Marmot, 1992) and is composed of four of the seven items of a validated severe depression subscale, and has been used in previous publications. (Stansfeld et al, 2003;Nicholson et al, 2005) We did not find a consistent cross-sectional relationship between high levels of inflammation and depressive symptoms. It is possible that the cognitive symptoms of depression we measured are not associated in the same way with inflammation as measures of depression which include neurovegetative symptoms which might more readily be expected to be associated with inflammation.…”

“…This has been validated within the Whitehall II study, (Stansfeld, Marmot, 1992) based on principal components factor analysis (Nicholson et al, 2005) and compared with the seven-item severe depression subscale from the GHQ-28. (Stansfeld et al, 2003) The items requested whether, compared to a usual state, the participant has recently: been thinking of yourself as a worthless person; felt that life is entirely hopeless; felt that life isn't worth living; and, found at times you couldn't do anything because nerves were too bad. These items assess cognitively-based symptoms of depression only.…”

“…The test-retest reliability was r=0.78 in a sub-sample of 286 baseline participants who repeated the GHQ within a month. (Stansfeld et al, 2003) Covariates Common correlates of inflammation and/or depression were included as covariates in the analysis and were obtained from phase 3 unless otherwise stated. (Woodward et al, 1999;Woodward et al, 2003;Elovainio et al, 2006) Sociodemographic data included age (in five-year categories), sex, observer-assigned ethnicity (White, South Asian, Black and other categories), and adult socioeconomic position based on participant's last known Civil Service employment grade categorised as high (administrators), middle (executives, professionals and technical staff) and low (clerical and office support staff).…”

The distribution of wellbeing in Ireland

“…We can also examine the extent to which well-being is affected by gender, health status, age and the presence of children. Many studies have found that socio-demographic factors play an important role in explaining inter-individual variability in well-being 14,15,16 and depressive symptoms 17,18 , as well as in physical morbidity 19,20,21,22 .…”

Informal work, unemployment and health in Brazilian metropolitan areas, 1998 and 2003

“…The association between mental health problems and unemployment, as well as atypical and temporary employment has been observed in studies carried out in Brazil 28 and elsewhere 7,25,27 . In one study among English civil servants, employment characteristics were the most influential factors in the inverse gradient between "employment grade" and depressive symptoms 29 . Unemployment and job insecurity are considered to have a negative influence on mental health not only on account of the financial implications, but also due to the psychosocial aspects such as the breakdown of an individual's time structure, a lack of future perspectives, lower self-esteem and dissatisfaction with the working situation 30 .…”