Depressed have high rates of physical illness

People with recurrent depression have high rates of many common physical illnesses, such as gastric ulcer, rhinitis/hay fever, osteoarthritis, thyroid disease, hypertension and asthma, a new study has found.

The study compared 1546 people with recurrent depression with 884 psychiatrically healthy controls in terms of past treatment for 16 different physical disorders.

Since many medical disorders are related to obesity, the researchers also examined body mass index (BMI) in both groups.

It was found that 15 physical disorders were significantly more frequent in people with recurrent depression than in controls. However, when BMI, age and gender were taken into account, depression was found to predict 6 disorders - gastric ulcer, asthma, rhinitis, hypertension, thyroid disease and osteoarthritis.

For the remaining physical health problems - diabetes, epilepsy, hypercholesterolaemia (high blood fats), kidney disease, liver disease, heart attack, osteoporosis, rheumatoid arthritis and stroke - the difference between those with and without each disorder could be accounted for by BMI, age or gender.

Both men and women with recurrent depression had significantly higher BMIs than men and women in the control group.

Although the percentages of the two groups were similar in the overweight range, a greater proportion of people with depression were in the obese range, and substantially fewer were in the normal range, compared with controls.

Thus, around a quarter of the men and women with depression were obese, which increases their susceptibility to physical health problems. In this study, obesity was associated with an increase in self-reported rates of hypercholesterolaemia, type II diabetes and heart attack.

High rates of obesity may be caused by some antidepressant medications, or arise because people who are depressed take less exercise and/or 'comfort' eat. However, it is also possible that genetic factors may be involved.

Evidence from previous research, and from this study, lends some support to the hypothesis that there are shared causal factors between recurrent depression, obesity and certain physical disorders.

One possible explanation for this is the effect that stress, and stress hormones, have on the brain and body. For instance, high levels of the stress hormone cortisol may link both obesity and gastric ulcers with depression.

The researchers comment that inflammatory processes that activate stress hormones may also link depression with asthma, hay fever, osteoarthritis and hypertension. These are speculations, however, and need confirmation from further studies.

Although long neglected, the physical health of people with schizophrenia is starting to be addressed, particularly in relation to the weight gain caused by antipsychotic drugs. This study suggests that attention needs to be paid to the physical health needs of people with depression.

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Farmer A, Korszun A, Owen MJ, et al. Medical disorders in people with recurrent depression. Br J Psychiatry 2008 192: 351-355   [Abstract]