Allergies are the worst, and they seem to increase in intensity every single year. For weeks during the months of spring, you are congested, your eyes water and you are so fatigued that you cannot go outside to enjoy the beautiful blossoming of spring – and that's just if you have seasonal allergies. I am allergic to dust, which means that I have all the above symptoms and none of the respite from the remaining three seasons.

Even though scientists say that allergies are indicative of a hyperactive immune system, that knowledge does not make the symptoms easier to cope with. However, researchers in Norway have managed to come up with a ray of light for people with allergies though – allergy sufferers have as much as a 50 percent decreased risk of developing brain tumors.

Researchers have noticed a link between allergies and this type of tumor, called glioma, before. Because they knew that the tumors suppressed immune systems in order to grow, they were unsure whether allergies kept the tumors at bay or whether tumors suppressed the immune system response to allergens.

The researchers found their answers in one of Norway's carefully catalogued blood banks. At the Janus Serum Bank in Oslo, they have kept the blood records from individuals for the past 40 years, collected during annual medical exams or volunteer donations. Norway has also kept records of every case of cancer since 1953.

Judith Schwartzbaum, associate professor of epidemiology at Ohio State University, and her team analyzed blood samples from 594 people who had been diagnosed with glioma, and 374 people who had the particularly common and lethal glioblastoma. (The average life expectancy after a glioblastoma diagnosis is just one year; 60 percent of people with brain tumors have glioblastoma.) The blood samples were taken 20 years before their glioma diagnoses, and were compared with 1,177 samples of people who had not been diagnosed with glioma. Researchers tested for common types of allergens, like dust mites, cat, dog, horse dander and pollen.

Schwartzbaum and her colleagues found that women who had specific allergy-related antibodies in their systems were 50 percent less likely to develop glioblastoma. For men, that difference was not as pronounced as for women. However, researchers did find that, for men with specific and unknown allergy-related antibodies, their risk was sliced by 20 percent.

In fact, the researchers say, the absence of allergies is the greatest risk factor for this type of brain tumor.

The study was published in the Journal of the National Cancer Institute.

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