Friday, April 9, 2010

Words Can Trigger Pain Centers in the Brain

Pain and the Great Brain Robbery! Part 1

New research shows that merely hearing pain-related words can fire-up the brain's pain centers. The clinical question is, when patients discuss, or just think about, their chronic physical pain symptoms can it actually make the pain worse?

Storage of painful experiences in memory is of biological advantage, since it encourages the avoidance of future situations that might cause physical pain and possibly be life threatening. Past research suggests that areas of the brain’s “pain matrix,” serving as a repository of painful memories, can be activated by environmental cues such as certain images or words. However, the particular areas of the brain affected and the specificity of verbal cues was unknown.

Psychologists at Friedrich Schiller University in Germany had 16 subjects read pain-related words while imagining situations that corresponded to each word [Richter et al. 2010]. Participants were then asked to repeat the exercise but were mentally distracted by a brain-teaser as they read the words. During the experiments, all subjects had their brains scanned with functional magnetic resonance imaging (fMRI). Words such as "plaguing," "tormenting," and "grueling" associated with pain triggered specific areas in the “pain matrix” that retain memories of painful experiences. Conversely, negative words that were not pain-related — such as "disgusting," "terrifying," and "horrible" — did not activate those brain regions. As expected, reading neutral or positive words also did not produce activity patterns comparable to the pain-related words. Even when subjects were mentally distracted the pain-related words still had a more significant impact than the other verbal cues.

Limbic StructuresCOMMENTS: This study size was small, which is typical of brain-imaging research, and there also may have been linguistic nuances particular to German language and culture. Still, the concepts involved have some neurobiological precedents. When subjects were instructed to imagine situations associated with pain-related words, specific areas in the “pain matrix” were activated — namely, the dorsolateral prefrontal cortex, inferior parietal gyri, and precuneus — which broadly comprise a part of the limbic-brain complex (some limbic structures, brightly-colored, are shown in the illustration) . The limbic brain is at the heart of central pain processing, signaling alarms and lending emotional overtones and meaning to the experience, among other functions. For example, negative perceptions of fear, anxiety, and subsequent suffering are mediated by the limbic brain. [More to come about the limbic brain and pain in future postings in this series.]

This study suggests that pain-related words, themselves, may have neurobiological powers to significantly affect patient health and well-being. The question remains, however, what role verbalizations of painful experiences or symptoms may play for chronic pain patients. Is it possible that simply discussing their pain with healthcare providers or other persons activates the limbic brain in ways that intensify the pain experience for these patients? Does thinking about the pain, as a form of pre-verbalization, make it worse? Further research will be needed to provide answers, but these are questions for healthcare providers to consider if a patient appears to become more agitated and distressed when describing pain symptoms. It seems plausible that words can hurt — physically.

REFERENCE: Richter M, Eck J, Straube T, Miltner WHR, Weiss T. Do words hurt? Brain activation during explicit and implicit processing of pain words. Pain. 2010;148(2):198-205 [abstract here].