Study suggests depressed people experience a negative bias in the processing of pain

New research indicates that depression impacts the subjective perception of pain. The findings appear in the journal Frontiers in Psychiatry.

“As a clinician, I encounter many patients suffering from depression, and pain symptoms seem to be extremely common in this population. Up to 80% of patients who present in primary care settings with major depression suffer from physical symptoms, and the nature and mechanisms of this bidirectional relationship is intriguing and of importance to our understanding and treatment of depression,” said study author Uri Nitzan, the director of the depression and crisis intervention department at the Shalvata Mental Health Center.

Using a temperature stimulation device, the researchers compared the pain sensitivity of 25 patients suffering from a moderate to severe depressive episode to 25 matched controls. They found that depressed participants tended to rate lower temperatures as more painful. Depressed participants also reported more perceived pain during the last month.

“The present study stresses that a negative bias in the processing of pain stimuli might be central in the pathophysiology of pain in patients with unipolar depression. Possibly, depressed patients’ increased evaluation of pain intensity accords with their cognitive bias, and is similar to their processing pattern of facial expression,” Nitzan told PsyPost.

“Consistent evidence demonstrates that individuals suffering from depression have a negative response bias towards sadness, so that they tend to evaluate positive (happy), neutral, or ambiguous facial expressions as sadder or less happy than do non-depressed subjects.”

The findings shed some light on why pain symptoms are associated with depression. However, more research is needed.

“This is a preliminary study, and further studies are needed to unravel the aberrations in pain processing among depressed patients along the course of time and in patients without antidepressant medications,” Nitzan explained.

“Traditionally, pain symptoms in depression were attributed to changes in pain perception and modulation. We suggest that it is the processing of the emotional aspects of pain in the cortex that are responsible for excessive pain symptoms reported by depressed patients.”

The study, “Initial Evaluation of Pain Intensity Among Depressed Patients as a Possible Mediator Between Depression and Pain Complaints“, was authored by Uri Nitzan, Maya Hecht, Yoram Braw, Hagai Maoz, Yechiel Levkovitz, David Yarnitsky, Yelena Granovsky, and Yuval Bloch.