Final answer:
The statement is true: mortality rates are typically higher in the underweight elderly compared to the overweight elderly, as undernutrition can lead to higher frailty and increased vulnerability to diseases.
Step-by-step explanation:
The statement that mortality rates are higher in the underweight elderly than in the overweight elderly is generally considered to be true. In geriatric health, there's a concept known as "heterogeneous frailty" which refers to the variable risk of death among individuals in a population. This concept implies that due to a range of factors including genetics, environment, and socioeconomic status, some individuals are more susceptible to disease and death. Typically, those with higher frailty, which can be associated with being underweight, have a higher mortality rate. Being overweight in the elderly can sometimes act as a protective buffer, though it is associated with other health risks. Underweight elderly often face issues associated with malnutrition and a weakened immune system, which increases their vulnerability to infectious diseases and other complications. Therefore, having a healthy weight, or sometimes even being slightly overweight, may confer a survival advantage in the elderly population.