Allergic reactions can occur without being triggered by an allergen such as grass or birch pollen - it is enough for the patient to be back in the same place in which he or she was previously exposed to the allergen, as researchers at the University of Tübingen have found.
However, this kind of conditioned reaction to an intrinsically neutral and harmless situation only happens after a sleep phase that follows the conditioning.
The new study on the influence of psychological factors on allergic reactions was led by Dr. Luciana Besedovsky and Professor Jan Born from the Institute of Medical Psychology and Behavioral Neurobiology.
The findings go some way towards explaining why allergic reactions are frequently observed as a form of placebo reaction when the original allergen is not even present. The study has been published in the latest Proceedings of the National Academy of Sciences.
The research team recruited volunteers with allergic rhinitis, who were then given a nasal spray containing their respective allergens (grass or birch pollen) in a neutral test room. The strength of the allergic reaction occurring in the test persons was measured by the amount of a specific enzyme in the nasal secretion.
Half of the test persons went to sleep for eight hours after this experiment, while the other half had to stay awake until the following evening. One week later, the experiment was repeated in the same test room. But this time no allergens were given.
The test persons reacted with allergic rhinitis already shortly after entering the room - but only those from the group that slept. Dr. Luciana Besedovsky, Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen Related Stories
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