Does pain cause depression, or does depression cause pain? Many research studies have been conducted trying to establish and analyze the connection between pain and depression. A review of several of these studies, which was published in 2003, concluded (in part) that there was more pain found in those seeking help with depression and more depression in those seeking help with pain than when either condition was examined individually.

The two common medical conditions frequently occur together, respond to similar treatments, share the same brain chemistry pathways, and can become worse when not treated as co-existing diagnoses. In spite of this, underlying depression is seldom recognized by the physician or the patient when pain is the reason for the office visit. A work-up can include a complete history and physical exam, labs for various painful conditions, and x-rays; oftentimes, the patient is referred to a pain specialist or physical therapist. Approximately 50 percent of the time the work-up in a primary care setting does not include evaluation for depression.

Included in the 2003 review were 14 studies where the patient sought treatment for depression and then was assessed for pain; also included were 42 studies where the patient sought treatment for pain and then was assessed for depression. Excluded from the review were studies of patients whose pain had been diagnosed as a condition known to be painful (rheumatoid arthritis, fibromyalgia, diabetic nerve pain, etc.) Interestingly, there appears to be less depression in that population. The authors were more interested in chronic pain for which no concrete medical explanation could be found.

Conclusions drawn from this review:
1. Pain in a depressed sample and depression in a pain sample are higher than when these conditions are examined individually: 65 percent of patients with depression experience one or more pain complaints, and depression exists in 5-85 percent (depending on the study) of patients with pain

2. When pain is the chief complaint, depression is often not recognized; at least 75 percent of the time, patients with depression seek medical care for symptoms of pain

3. More studies are needed to determine if getting rid of pain results in less symptoms of depression and whether treating depression results in improvement of pain.

Some of the studies showed that when depression and pain are treated with anti-depressants, both conditions improve simultaneously. This appears to be especially true when some of the newer anti-depressants are used. These medications work on the brain chemicals (serotonin and norepinephrine) associated with helping both conditions. The older anti-depressants (tricyclics) have been studied. The authors suggest more studies be done on the newer anti-depressants. They also suggest the need to adopt a model of assessing for depression when treating chronic pain.

For more information, refer to: "Depression and Pain Comorbidity," Bair, M MD MS; Robinson, R MS; Katon, W MD; Kroenke, K MD; Archives of Internal Medicine, 2003 Nov 10;163 (20).