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Insulin resistance and depressive symptoms in middle aged men: findings from the Caerphilly prospective cohort study

BMJ 2005; 330 doi: (Published 24 March 2005) Cite this as: BMJ 2005;330:705
  1. Debbie A Lawlor, senior lecturer in epidemiology and public health (,
  2. Yoav Ben-Shlomo, senior lecturer in clinical epidemiology1,
  3. Shah Ebrahim, professor in epidemiology of ageing1,
  4. George Davey Smith, professor of clinical epidemiology1,
  5. Stephen A Stansfeld, professor of psychiatry2,
  6. John W G Yarnell, reader in epidemiology and public health3,
  7. John E J Gallacher, senior lecturer in environmental epidemiology4
  1. 1 Department of Social Medicine, University of Bristol, Bristol BS8 2PR,
  2. 2 Centre for Psychiatry, Barts and the London, Queen Mary, University of London,
  3. 3 Department of Epidemiology and Public Health, The Queen's University of Belfast,
  4. 4 Department of Epidemiology, Statistics and Public Health, University of Wales College of Medicine
  1. Correspondence to: D A Lawlor
  • Accepted 10 January 2005


Insulin resistance may protect against depression, possibly through an effect on circulating free fatty acid concentrations and brain serotonin concentration,1 2 although a recent study contradicted these findings.3 Studies to date have either used indirect measures of insulin resistance,1 or they have been cross sectional.2 3 We assessed the association of insulin resistance with depressive symptoms in a prospective cohort.

Participants, methods, and results

The Caerphilly cohort study has been described in detail before.4 In phase I (1979-83), 2512 (89% of eligible) men aged 45-59 years from Caerphilly in Wales provided fasting blood samples. Insulin resistance (homoeostasis model assessment (HOMA) score) was derived from fasting insulin and glucose.5 HOMA scores were not calculated for men with diabetes or high fasting glucose (≥ 7.0 mmol/l).

In phases II (1984-88), III (1989-93), and IV (1993-7), depressive symptoms were measured by the 30 item general household questionnaire (GHQ). This was validated at phase II in a subgroup (n = 97) by comparison with a clinical interview schedule given by a psychiatrist blinded to the …

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