Harrison Ford, Usain Bolt, and Peyton Manning have all had to deal with back pain. And they're just some of the 31 million Americans who, on any given day, contend with that agony.

What causes all this discomfort? Sometimes it's a slipped disc, muscle spasm, or congenital spine problem like scoliosis.

Other times, however, the source of pain is harder to diagnose, and conventional medical treatments don't provide relief.

A study published in the journal PAIN suggests that in such cases, stress and emotional/psychological factors may be the cause.

For instance, stress can cause vasodilation, which makes a person blush. So, say the researchers, stress or repressed emotions can trigger physiological changes (in your nervous system and muscles) that cause nonspecific back pain.

To treat such cases, the researchers used a 12-week, psychophysiologic symptom relief therapy (PSRT) program. It educates patients about the links between stressors, emotions, and pain, and helps reverse ingrained associations of certain activities (bending, sitting) with pain. In addition, it teaches a mindfulness-based stress-reduction technique.

After four weeks, the researchers saw an 83% decrease in reported pain disability in PSRT participants. And after six months, 64% of patients in the PSRT group were pain-free.

PSRT, which was developed at Beth Israel Deaconess Medical Center, isn't yet available to the public.

However, if you can't find a solution to your lower back pain, ask your doctor about pain-related psychological therapy. And check out "Mindfulness: 17 Simple Ways to Ease Stress" at health.clevelandclinic.org.