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22-05-2012 | General practice | Article

When in pain, distract yourself


Free abstract

MedWire News: Mental distraction reduces the perception of pain through a mechanism related to a spinal process involving opioid neurotransmission, researchers suggest in Current Biology.

Christian Sprenger (University Medical Center Hamburg-Eppendorf, Germany) and team found that in individuals who are exposed to very high temperatures, mental distractions, such as performing a memory recall task, inhibit the response to incoming pain signals at the earliest stage of pain processing.

"The results demonstrate that this is not just a psychological phenomenon, but an active neuronal mechanism reducing the amount of pain signals ascending from the spinal cord to higher-order brain regions," commented Sprenger in a press statement.

The researchers noted that the effect of mental distraction on pain perception was due in part to endogenous opioids.

They asked 20 healthy men (mean age 27.2 years) to complete two working memory tasks (1-back versus 2-back letter test) ‑ one easy, one hard ‑ while undergoing thermal pain stimulation in the dermatome C6.

This allowed the researchers to test whether spinal cord blood oxygen level-dependent (BOLD) responses to pain, assessed using functional magnetic resonance imaging (fMRI), were reduced during high working memory load compared with low working memory load.

Pain ratings showed a significant decrease during high working memory load compared with low working memory load, at mean scores on a visual analog scale of 48.3 versus 60.3.

This demonstrated that pain reduction was reduced by 19% when completing the harder of the memory tasks while being distracted, indicating that the working memory load manipulation successful decreased perceived pain intensity, comment the researchers.

The finding was reflected by the fMRI results, which showed that the strongest BOLD response to pain was observed during the easy memory task approximately at the same site as the main effect of painful stimulation.

The researchers then conducted a second experiment involving 15 men (mean age 25.7 years) to investigate whether reduced pain perception during high cognitive load is monitored by endogenous opioid neurotransmission. For this experiment, they employed the same behavioral paradigm in combination with a pharmacologic challenge using the opioid-antagonist naloxone.

Sprenger et al found that the analgesic effect of working memory load by the opioid antagonist naloxone was reduced by 40.5% compared with saline, providing "evidence that endogenous opioids play an essential role."

"Our findings strengthen the role of cognitive-behavioral therapeutic approaches in the treatment of pain diseases, as it could be extrapolated that these approaches might also have the potential to alter the underlying neurobiological mechanisms as early as in the spinal cord," they said.

By Piriya Mahendra

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