Over 8,000 married couples aged between 30 and 74 years of age took part in the study. After adjustments were made for age, obesity and smoking status in both partners it was found that the partners of people with asthma, depression and peptic ulcer disease were 70% more likely to suffer from the disease themselves. People with partners suffering from other conditions such as high blood pressure and hyperlipidaemia (excess cholesterol in the blood) were also more likely to suffer from the same conditions as their spouse.
The link is most likely to be caused by the environment within which the couple live, with shared environmental factors putting cohabiting partners at risk of developing the same diseases. The finding for asthma may be due to shared diet or shared exposure to allergens, whilst findings for hypertension and hyperlipidaemia suggest that diet and the pattern of physical exercise shared by couples has an important role in the disease's cause. Another possible explanation for the findings is that couples may share similar attitudes towards healthcare and seeking health advice.
The researchers claim their findings could have implications for screening and other interventions. Interventions targeted at couples may prove more effective and screening spouses for some diseases should be considered, they conclude.