Why are the elderly more susceptible to respiratory infections like pneumonia?

The elderly are more susceptible to respiratory infections like pneumonia primarily due to a decreased cough rate. As people age, various physiological changes occur, including a decline in lung function and changes in the respiratory system. A reduced cough reflex can impair the body's ability to effectively clear mucus and pathogens from the airways, leading to an increased risk of respiratory infections.

The cough reflex is crucial in protecting the lungs and upper airways from irritants and infections. When this reflex is diminished, there is a greater likelihood that bacteria and viruses can establish an infection, as the body's primary defense mechanism is compromised. Furthermore, aged individuals may also have pre-existing conditions that can exacerbate this susceptibility, such as chronic obstructive pulmonary disease (COPD) or heart failure, which further hinder respiratory function.

While the other options suggest factors that could have a protective effect or promote health, they do not apply to the elderly in the context of respiratory infections. An increased lung capacity, a better immune response, or higher physical activity levels are not generally characteristics that define the aging process in a way that protects against pneumonia. Instead, the physiological changes that occur with aging, such as a decreased cough rate, clearly highlight the increased vulnerability of older adults to respiratory infections.