Causes Make an Appointment Refer a Patient Ask a Question Reviewed by National Institute of Arthritis and Musculoskeletal and Skin Diseases. (April 01, 2009) The cause of polymyalgia rheumatica is not known, but research has shown that it is associated with immune system problems, genetic factors, and an event, such as an infection, that triggers symptoms. The fact that polymyalgia rheumatica is rare in people under the age of 50 and becomes more common as age increases indicates that it may be related to the aging process. Symptoms Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.