They studied 218 RA patients who provided information about their pain levels, depression symptoms, year of RA onset, smoking and drinking habits and socioeconomic demographics. The researchers collected blood samples from the patients to measure levels of CRP, a protein produced by the liver. Levels of CRP rise during periods of acute inflammation. RA treatments often focus on reducing inflammation.

The study found that inflammation and depression each independently increased the likelihood of severe pain. The combined effects of high CRP levels and depression predicted severe pain even more strongly.

"Results of our research demonstrate the potential for clinicians to improve pain control by addressing their patients' psychological symptoms in addition to conducting anti-inflammatory therapy," study leader Dr. Masayo Kojima said in a news release.

The findings suggest that psychotherapy and/or psychotropic medication might be a priority for RA patients who experience severe pain without elevated levels of CRP.

"A clinical approach that takes into account both the body and the mind could have benefits and could enable optimal pain control," the researchers at Nagoya City University and Nagoya University Graduate Schools of Medicine said in a news release.

The study appears in the August issue of the journal Arthritis Care & Research.

Another report in the same issue found that RA patients with depressed spouses suffered worse disease progression over the one year studied. The Canadian study included 133 married RA patients.

"Our findings highlight the key role played by the spouse in disease course of individuals with RA, and point to the importance of including the spouse in clinical interventions," Anita DeLongis and colleagues at the University of British Columbia said. "The mood and mental health of the marital partner or other key members of the family may be critically important to consider in developing more effective and evidence-based treatment for RA patients."

More information

The Arthritis Foundation has more about rheumatoid arthritis .