Women with major depression are more likely than women who are not depressed to have allergies, and allergies also appear to be more common in men with nervous, anxious personalities, a study has found.

The findings, from a national survey of 3,032 U.S. adults, suggest there is a relationship between depression or neurotic personality traits and allergy - and suggest that these associations are different for men and women.

Past studies have linked depression and allergies, though it’s not clear if one leads to the other. One hypothesis has been that people with “neurotic” personalities - who have a tendency to be nervous, anxious and moody - might be prone to both depression and allergies. The trait is already thought to be a risk factor for depression.

To test this idea, the authors analyzed data from a nationally representative survey of Americans between the ages of 25 and 74. Depression and personality traits were all measured using a standard battery of questions.

Overall, the researchers found, both depression and “neuroticism” were associated with a greater likelihood of allergy. Study participants with major depression were 50 percent more likely to have allergies than those without depression, while adults with neurotic personalities were 22 percent more likely to have allergies than their peers without neurotic personalities.

However, a closer analysis showed that depression and allergies were linked only among women, and neurotic personality did not explain the relationship.

In contrast, men with neurotic personalities had a higher risk of allergies, but there was no connection between depression and allergies.

Dr. Renee D. Goodwin of Columbia University’s Mailman School of Public Health, in New York, led the study, which is published in the journal Psychosomatic Medicine.

More research, according to Goodwin’s team, is needed better understand the connections between depression and allergies, and between neuroticism and allergies - as well as why there are sex differences.

In the case of depression, the researchers speculate, it’s possible that the disorder contributes to allergy development by impairing the immune system or through some other biological effect.

On the flip side, the stress of dealing with chronic allergies may lead to depression in some people.

Similarly, the relationship between neurotic personality and allergies could work in either direction, according to the study authors.

They note that people who are naturally anxious, for example, may be more sensitive to allergic responses and seek treatment for milder symptoms that other people might ignore.

On the other hand, although personality traits are thought to form early in life, it’s possible that allergies cause some people to think more negatively in general and respond to daily stresses with more anxiety.

SOURCE: Psychosomatic Medicine, January/February 2006.