a1 PenCLAHRC, Peninsula Medical School, University of Exeter, Exeter, UK
a2 Public Health Directorate, NHS Devon, Exeter, UK
a3 Epidemiology & Public Health Group, Peninsula Medical School, University of Exeter, Exeter, UK
a4 Department of Geriatric Medicine, School of Medicine, Cardiff University, Penarth, South Wales, UK
a5 Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
a6 Veterans Affairs Center for Practice Management and Outcomes Research, Ann Arbor, MI, USA
a7 Institute for Social Research, University of Michigan, Ann Arbor, MI, USA
Background The prevalence of psychological distress and common mental disorders has been shown to peak in midlife but analyses have ignored the association of poor material circumstances with prevalence. This study aimed to test the hypothesis that the midlife prevalence peak occurs only in lower-income households.
Method Pooled data were used from the annual Health Survey for England, a nationally representative cross-sectional study, on community-dwelling individuals aged ≥16 years from years 1997 to 2006 (n=100 457). 12-item General Health Questionnaire scores, reported mental illness diagnoses and receipt of relevant medication were assessed in relation to household income and age. Analyses were separated by gender and adjusted for age, ethnicity, smoking, social class, education and co-morbidities.
Results Prevalence of psychological distress, diagnoses and treatments rose with age until early middle age and declined subsequently. In analyses conducted separately by income categories, this pattern was marked in low-income groups but absent in high-income groups. Income-related inequalities in the prevalence of psychological distress were greatest in midlife; for example, in men aged 45–54 years the odds ratio of receiving psychiatric medication in the lowest income group compared with the highest was 7.50 [95% confidence interval (CI) 4.24–13.27] and in women aged 45–54 years the odds ratio of reporting mental illness was 10.25 (95% CI 6.16–17.05).
Conclusions An increased prevalence of psychological distress, common mental disorder diagnoses and treatment in midlife is not a universal phenomenon but is found only in those in low-income households. This implies the phenomenon is not inevitable but is potentially manageable or preventable.
(Received November 10 2009)
(Revised August 01 2010)
(Accepted September 23 2010)
(Online publication December 10 2010)