Anxiety and fear are strongly associated with pain, particularly as pain increases in severity. Pain increases anxiety because the person worries that the pain will never end. A sense of control is lost and feelings of helplessness ensue. Anxiety results in muscle tension and spasm, reducing blood flow and increasing tissue ischemia, releasing chemicals into the surrounding tissues that worsen the physical pain, and on the cycle goes. By addressing these fears about the person’s current and future life, some psychological relief can be provided even if the physical pain cannot be eliminated.
(Source: Chronic Pain: Biomedical and Spiritual Approaches, by Harold G. Koenig, M.D.)