"This is potentially a really important finding," said Alan Schatzberg, MD, the Kenneth T. Norris Jr. Professor of Psychiatry and Behavioral Sciences, who participated in the study published in the January issue of the journal Archive of General Psychiatry. "This will change how we view pain and depression."
Schatzberg said previously published research hinted that people with depression may be more likely to experience chronic pain and that depressed people with chronic pain may respond better to a class of drugs that treats both symptoms. If the relationship exists, then pain may be a symptom that guides doctors to the drugs they prescribe for depressed patients.
After hearing anecdotal evidence that certain drugs are more effective in depressed people who also have chronic pain, Schatzberg and his colleague Maurice Ohayon, MD, PhD, associate professor of psychiatry and behavioral sciences at the Stanford School of Medicine, tested the correlation using data collected previously by Ohayon. These data included information from 18,980 people in five European countries who agreed to answer health questions over the phone.
Among the participants, 17 percent had chronic pain and 4 percent had symptoms of major depression; however, 43 percent of those with major depression also had chronic pain. Of the symptoms, headaches and backaches were most commonly found in depressed people. People who had pain for 24 hours were also more likely to have major depression, indicating that continuous pain increases the likelihood of having a major depressive disorder diagnosis.
Schatzberg said he had no idea so many of the patients he treated for depression may also need treatment for chronic pain.
"I was totally shocked," he said. Now he'll know to ask his depressed patients if they also have chronic pain that should be treated, he said. He added that other doctors can monitor their chronic-pain patients for symptoms of depression.
When doctors first diagnose a person with depression, they use a checklist that includes symptoms such as changes in mood, appetite and sleep patterns to determine the severity of the person's depression along with the appropriate treatment. Schatzberg suspects that the presence of chronic pain should be added to this list as a symptom for assessing depression. He said that by more precisely diagnosing a person's symptoms doctors have a better chance of prescribing medication that will be effective in that patient.
The question now is which comes first: the depression or the pain. "We all have a certain amount of pain," Schatzberg said. "It could be that the perception of pain is greater in depressed people." He pointed out that many people with depression reported more headache, back pain or limb pain rather than pain stemming from disease.
Schatzberg added that future studies will look at how people with depression and chronic pain respond to different drugs used to treat depression.
Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at http://mednews.