Final answer:
Dementia is the medical factor that causes malnutrition and weight loss in older adults due to its impact on cognitive functions and appetite.
Step-by-step explanation:
The medical factor that causes malnutrition and weight loss in older adults is dementia. Dementia is a neurodegenerative disorder that affects cognitive functions including memory, thinking, and behavior. It can lead to a decline in appetite and difficulty in swallowing or understanding how to eat, resulting in malnutrition and weight loss.
For example, individuals with dementia may forget to eat or drink, lose interest in food, or have difficulty chewing and swallowing, leading to a reduced intake of essential nutrients. This can result in weight loss, weakness, and other health complications.