Which chronic condition is characterized by persistent pain in the muscles or joints in older adults?

Fibromyalgia is characterized by persistent pain in the muscles and joints, particularly affecting older adults. This condition is often accompanied by various other symptoms such as fatigue, sleep disturbances, and cognitive issues like memory problems. Unlike other conditions listed, fibromyalgia is specifically defined by its widespread musculoskeletal pain without obvious inflammation or damage to the joints or muscles.

Both rheumatoid arthritis and osteoarthritis primarily involve joint inflammation or degeneration, which may lead to pain, but they do not typically describe the widespread pain pattern seen in fibromyalgia. Osteoporosis is primarily a bone density issue that increases the risk of fractures rather than involving muscular or joint pain directly. Therefore, fibromyalgia's unique presentation of chronic, widespread pain makes it the most fitting answer to the question.