View all news

New from the International Journal of Epidemiology

Press release issued: 23 August 2004

Possible links between anxiety and heart disease are explored in the latest edition of the International Journal of Epidemiology. Other papers include studies on asthma and heart disease, and the possible health risks of mercury-based dental amalgam.

Anxiety and depression may lead to heart disease

-Are patients with asthma at increased risk of heart disease?

- Largest ever study examines effects of dental amalgam on health

  Anxiety and heart disease

A study of French power company employees has found a significant link between depression and the development of coronary heart disease (CHD).  The research is published today in the International Journal of Epidemiology (IJE), edited in the Department of Social Medicine at Bristol University. 

Anne Chevalier and colleagues in the health insurance department of France’s nationwide power company, Electricité de France – Gaz de France (EDF-GDF), studied 660 of the company’s male employees, aged between 31 and 55 years, who had presented with an initial clinical form of CHD between 1993 and 1997.

They found a significant association between heart disease and sick leave for any medical reason in the three years before its onset – an association that was strengthened when only absences for depression and anxiety were considered.  This association remained important when adjusted for socio-economic factors.  A previous sick-leave for depression or anxiety in the ten years before the heart disease diagnosis strengthened the association further.

Dr Chevalier said: “Complex relations seem to link markers of mental health and predictors of heart disease, with depression and anxiety appearing to play a major role in this chain.  The practical consequences of this study may help lead to recommendations for the management of depression.  Although it may be premature to take depression into account as a risk factor in its own right for CHD, our findings constitute an additional argument in favour of its role.”

Paper: C Allonier, A Chevalier, M Zins, O Catelinois, SM Consoli, M Goldberg and G Lahon: ‘Anxiety or depressive disorders and risk of ischaemic heart disease among French power company employees’ IJE 2004, Vol 33 No 4 pp 779-786

Asthma and heart disease

Carlos Iribarren of the Kaiser Permanente Division of Research in Oakland, California, and colleagues studied 70,047 men and 81,573 women in Northern California, aged between 18 and 85 years.  Asthma was ascertained by self-report and/or hospitalisation for asthma.  

After a median follow-up time of 27 years and adjusting for other factors such as age, ethnicity, smoking status, alcohol consumption and body mass index, asthma was found to be associated with a small increased risk of heart disease among women.  This association was found both in smokers, former smokers and never smokers, and in younger and older women.  By contrast, asthma was not associated with CHD among men.

Dr Iribarren said: “Coronary heart disease is now understood as a disease with an inflammatory basis.  Because asthma is also of an inflammatory nature, it may contribute to the development of CHD. 

“The interaction between sex and asthma as predictors of CHD is intriguing and deserves further testing.  It has been suggested that women may have a greater biological susceptibility to the inflammatory milieu of asthma, or greater susceptibility to the cardiotoxic effects of certain asthma medications.

“Further studies are needed to confirm or refute these findings and to elucidate sex-specific factors in asthma physiology or management potentially leading to athero-thrombotic disease.”

Paper: C Iribarren, I V Tolstykh and M D Eisner: ‘Are patients with asthma at increased risk of coronary heart disease?’ IJE 2004 Vol 3 No 4 pp 743-748

Dental amalgam

A new study into whether dental amalgam fillings containing mercury are hazardous to health has found little evidence of an association between amalgam and disease.  The research, carried out on people in the New Zealand Defence Force (NZDF) between 1977 and 1997, is published today in the International Journal of Epidemiology (IJE), edited in the Department of Social Medicine at Bristol University. 

The use of mercury in dentistry has been controversial since at least the middle of the nineteenth century as inorganic mercury can cause a wide variety of health problems, particularly in the nervous system and the kidneys.  Modern dental amalgam currently contains about 50% mercury and, although alternative dental materials are increasingly available, amalgam’s advantages, including low cost and durability, have maintained its popularity as a filling material.

The controversy has intensified over the last 20 years or so because highly sensitive analytical techniques have shown mercury to be continuously released from dental amalgam fillings and absorbed into the body.

Michael Bates of the School of Public Health, University of California, Berkeley and colleagues in New Zealand and Australia, used data on 20,000 people (84% males) from the NZDF’s own dental service which provides all military personnel with regular and consistent treatment and maintains comprehensive records. 

They found no association between dental amalgam and chronic fatigue syndrome or kidney disease.  A very small association was found between amalgam and multiple sclerosis.  As the cohort was relatively young, there were insufficient cases of Alzheimer’s or Parkinson’s to investigate the possibility of a link between amalgam and these diseases.

Dr Bates said: “The debate about possible health effects induced by dental amalgam is marked by an absence of adequate epidemiological studies.  Previous studies have mostly been small with limited exposure data.  By contrast, our study had a large sample size, detailed exposure data and a consistent level of dental treatment across the cohort.

“This study is the most comprehensive so far to investigate the amalgam safety issue and generally provides reassurance.  Some important questions remain, however, and it is essential that the cohort be followed up in the future to establish whether there were any associations with rarer diseases and diseases more common in the elderly.”

Paper: M N Bates, J Fawcett, N Garrett, T Cutress and T Kjellstrom: ‘Health effects of dental amalgam exposure: a retrospective cohort study’ IJE 2004, Vol 33 No 4 pp 894-901

The International Journal of Epidemiology

The International Journal of Epidemiology is a key journal in the field of epidemiology and public health, published six times per year by Oxford University Press.  It is edited at the Department of Social Medicine, University of Bristol, which is a leading centre for epidemiology, health services research and public health in the UK and was one of only three to be awarded the top 5* grade in the 2001 Research Assessment Exercise.


Edit this page