Mental disorders and increased risk of obesity: possible link
7 October 2009
People with common mental disorders are at increased risk of becoming obese, according to new UCL research.
Professor Mika Kivimäki of UCL Epidemiology & Public Health led research published today on the website of the British Medical Journal that shows that individuals with chronic or repeat episodes of common mental disorders, such as depression and anxiety, are particularly at risk of becoming obese.
Previous studies report contradictory results and it remains unclear if common mental disorders lead to an increased risk of obesity, or if obesity is a risk factor for future mental disorders. Understanding the connection between these common conditions is vital because they have a significant impact on health care systems and could aid effective treatment and prevention.
The UCL findings are based on four medical screenings of 4,363 British civil servants aged between 35 and 55 years old, over a 19-year period between 1985 and 2004 (the Whitehall II study).
Each screening included a standardised assessment of common mental disorder (General Health Questionnaire) and measurement of height and weight from which body mass index (BMI) was calculated.
After adjusting for several factors, weight gain was more common among individuals with common mental disorder symptoms at the start of the study than among those who were symptom free.
Individuals with a common mental disorder at all three preceding screenings were twice as likely to be obese at the final screening compared to individuals who exhibited no symptoms at all previous screenings.
The researchers also found evidence that people who experienced more incidences of a common mental disorder had a greater risk of weight gain and obesity.
Contrary to some previous research, there was little evidence that obesity leads to common mental disorders in people with no pre-existing mental disorder.
"In this population of British middle-aged adults, common mental disorder is predictive of subsequent weight gain and obesity," said Professor Kivimäki. The authors call for more research to verify whether the findings can be applied to wider populations.
The Whitehall II study was set up by Professor Sir Michael Marmot (UCL Epidemiology & Public Health) to investigate the importance of social class, psychosocial factors and lifestyle as determinants of disease by following a cohort of 10,308 men and women.
The study began by looking at the health of working people. It now seeks to answer questions about how previous and current circumstances affect health and quality of life in an ageing cohort.
The Whitehall II study is funded by the Medical Research Council, British Heart Foundation, National Heart, Lung and Blood Institute and the National Institutes of Ageing.