title: Social inequality in physical and mental health comorbidity dynamics.
abstract: OBJECTIVE
  To examine how socioeconomic position influences physical and mental health dynamics.
  
  
  METHODS
  The Whitehall II study of civil servants collected questionnaires on six occasions from 1991/93 to 2006/07. Civil service grade measured socioeconomic position and Short Form 36 General Health Survey component scores rated physical and mental health. Bivariate growth curve models of physical and mental health over 15 years were estimated for high, medium, and low grades (n = 8309).
  
  
  RESULTS
  At baseline, levels of physical and mental health were correlated for participants in low grades only. Among study participants in medium grades, mental health was maintained over time, even as physical health decreased. Restoring mental health after a negative response to poor physical health was more difficult for some in low grades. Recovery from downturns in physical health associated with poorer mental health also depended on better socioeconomic circumstances There was greater variability in baseline levels and rates of change in the mental and physical health of those in lower grades compared with higher grades.
  
  
  CONCLUSIONS
  Homeostatic mechanisms may vary by socioeconomic position. The greater variability of change in health function for those in lower grades implies considerable scope for improvement if sources of variation in health within disadvantaged groups that are amenable to intervention can be identified.
authors.affiliation: Institute for Social and Economic Research, University of Essex, Colchester, UK. asacker@essex.ac.uk
authors.forename: Amanda
authors.initials: A
authors.lastname: Sacker
authors.forename: Jenny
authors.initials: J
authors.lastname: Head
authors.forename: David
authors.initials: D
authors.lastname: Gimeno
authors.forename: Mel
authors.initials: M
authors.lastname: Bartley
mesh_terms: D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D015897:Comorbidity; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008603:Mental Health / Q000706:statistics & numerical data*; D008875:Middle Aged; D015233:Models, Statistical; D009790:Occupations / Q000145:classification* / Q000706:statistics & numerical data; D010809:Physical Fitness; D011788:Quality of Life; D012307:Risk Factors; D012737:Sex Factors; D012923:Social Class; D012944:Social Support; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires