Polymyalgia Rheumatica (PMR): Causes

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.