Mechanisms of Allergic Diseases in the Elderly
Overview of the Immune System
A recent article in *Immunity & Ageing* examines the various mechanisms associated with allergic diseases in older adults. The immune system is crucial for defending against foreign substances and pathogens. Throughout life, immune cells can become sensitized to react against harmful entities; however, allergic reactions arise when the immune system overreacts to harmless substances. Immediate hypersensitivity is a common type of allergic reaction, encompassing conditions such as anaphylaxis, asthma, and eczema. Approximately 25% of individuals in industrialized countries experience these reactions, influenced by factors including climate, diet, pollution, and gut bacteria composition.
Hypersensitivity in the Elderly Population
Most studies on immediate hypersensitivity have primarily focused on younger individuals. As life expectancy increases and the elderly represent a growing demographic, especially in industrialized nations, it is essential to investigate this condition in older populations. A research team from Italy reviews the current literature on both immunological and non-immunological mechanisms behind allergic diseases in elderly patients in their article published in *Immunity & Ageing*.
With aging, various aspects of the immune system decline, resulting in impaired function. Key characteristics of an aging immune system include an imbalance in immune cell subtypes and decreased generation of new T cells, which are vital for cell-mediated immunity. As age progresses, alterations in almost all types of immune cells lead to chronic inflammation and increased allergic immune responses. This decline in immune cell function also significantly reduces the effectiveness of vaccinations; for instance, the influenza vaccine offers considerably less protection for older adults.
Allergic Rhinitis and Bacterial Composition
Allergic rhinitis, commonly known as hay fever, significantly impacts the nasal area and is prevalent in older populations. However, research on physiological changes in the nasal region with aging is limited. Some studies suggest that specific types of rhinitis may develop following infections, particularly after intensive treatments such as surgery and radiation therapy. The increased risk of allergic rhinitis in elderly individuals is believed to stem from changes in the bacterial composition within the nasal cavity, which can profoundly affect the immune system.
Asthma in the Elderly
Asthma is another prevalent condition among older adults, contributing to morbidity and mortality. Patients are often classified into two categories: those who have had asthma since childhood and those with late-onset asthma. Diagnosing asthma in the latter group proves challenging due to symptom overlap with heart conditions and chronic obstructive pulmonary disease (COPD). Additionally, older patients frequently attribute their symptoms to normal aging rather than recognizing the disease. The exacerbation of asthma symptoms is closely linked to viral infections, putting older individuals at higher risk for complications as their immune systems weaken.
Skin Allergies in Aging Adults
Skin allergies also pose significant challenges for older individuals, as aging results in diminished skin structure and function. Hormonal changes, particularly in females, can exacerbate skin aging. This process can lead to various skin conditions, including dryness, itching, melanoma, and other diseases. The decline in skin health is attributed to fewer skin cells, slower turnover of new cells, reduced lipid production, and increased permeability.
Conclusion
Allergic diseases, affecting between 5% and 10% of the elderly population, are becoming increasingly prevalent. This article highlights critical characteristics and factors related to various allergic diseases, underscoring the serious implications of aging on immune function. Advancements in the treatment of allergic diseases in the elderly are necessary to address this pervasive issue.
Author Information
Written by Branson Chen, BHSc.
Reference
Di Lorenzo G, Di Bona D, Belluzzo F, Macchia L. Immunological and non-immunological mechanisms of allergic diseases in the elderly: biological and clinical characteristics. *Immunity & Ageing*. 2017 Dec;14(1):23.
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