Final answer:
Age-related changes that increase the risk of infections include the decline of the immune system's function, known as immunosenescence, beginning around age 50; thymic involution; increased chronic health conditions; and physical and cognitive declines.
Step-by-step explanation:
As individuals age, several age-related changes occur that increase the risk of infections. One of the central factors contributing to a higher susceptibility to infections is a process known as immunosenescence, which describes the gradual decline of the immune system's effectiveness. This decline starts around age 50 and becomes more pronounced with advancing age. Immunosenescence leads to a decreased capacity to fend off pathogens, resulting in a higher frequency of infections and slower wound healing in the elderly.
The aging process is also linked to thymic involution, the progressive shrinkage of the thymus gland that reduces the production of thymocytes, crucial for the immune response. Chronic health conditions, such as heart diseases, respiratory syndromes, and type 2 diabetes, become more prevalent with age and can exacerbate the risk of infection. Compounded by age-related cognitive and physical declines, including muscle weakness, slower reflexes, and potentially cognitive impairment as seen in diseases like Alzheimer's, the body's ability to manage and recover from infections diminishes.
Additionally, aging may lead to an increased incidence of nosocomial (hospital-acquired) and opportunistic infections. The skin, being the first line of defense, when compromised by age-related changes, can increase the susceptibility to skin infections, sinusitis, and food poisoning. The changes in the immune system can also render the elderly more vulnerable to diseases that were once rare, such as certain autoimmune disorders, due to a lack of early immune challenges.