The brain as a target organ for allergic and irritant sensitivity: A review and suggestions for research

Abstract

Objective: Clinical descriptions of behavioral and neurological manifestations of allergy and irritant sensitivity are described. Public health implications and mechanisms are discussed, with recommendations for further research. Data sources: MedLine searches of articles combining the terms allergy, asthma, rhinitis, irritant rhinitis, irritant asthma, chemical sensitivity, and multiple chemical sensitivity syndrome were combined with searches on fatigue, chronic fatigue syndrome, depression, anxiety, and insomnia. Textbooks of allergy and books on irritant sensitivity were reviewed. Data extraction and synthesis: Quantitative evidence on the neurological and psychiatric manifestations of asthma and chemical sensitivity is limited, though a few controlled studies exist. Irritant sensitivity is generally self-reported in studies, though objective parameters exist for diagnosis of allergy. Clinical descriptions and controlled studies are analyzed for their support for the hypothesis that the brain is a target organ for allergic and irritant sensitivity. Conclusions: This literature review supports the hypothesis that the brain is a target organ for allergic and irritant reactions with neuropsychological manifestations. Technology exists to conduct controlled challenge studies using real-time monitoring of cerebral function with state-of-the-art imagining modalities, correlating neuropsychological manifestations, and serum biomarkers. This research could have implications for treatment and prevention of some forms of neuropsychological illnesses.