Mice with companions seemed to experience less neuropathic pain than those kept in isolation.


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PROBLEM: Peripheral neuropathy, a side effect of diabetes and one of the most common chronic diseases in the U.S., manifests itself as persistent pain and numbness in the hands and feet. Medications provide some relief, but no cure is currently known to exist.

METHODOLOGY: Researchers at Ohio State University separated their lab mice into two groups. Some were left socially isolated, while the others were each given a cage-mate to keep them company. Some mice from each group were also exposed to three separate periods of stress.

After a week of either hanging out with their cage-mate or presumably getting to do some private soul-searching, half of the mice were subjected to a nerve surgery that caused a similar pain to that experienced by people with peripheral neuropathy.

RESULTS: While normally mice are down with high-fives, those who had undergone the operation exhibited pain by withdrawing their paws when lightly touched by the researchers. The mice who had spent a week in solitary confinement and were exposed to stress has the lowest threshold of pain: They withdrew their paws at the lightest stimulus. They also had increased markers of inflammation in their brain and spinal cord tissue. Mice who lived with a "social partner" (or, if we want to anthropomorphize it, a "friend") and who were non-stressed were able to withstand much higher levels of pain, but even those who were exposed to stress had a higher threshold than those who were isolated.

CONCLUSION: Companionship was shown to have both behavioral and physiological effects on mice, who experienced less pain from nerve damage when they were paired with another mouse.

IMPLICATIONS: Something as simple as not being alone has potential as an alternative treatment for peripheral neuropathy. What's more, the reductions in inflammation indicate that social companionship can have physical, observable effects. As Courtney DeVries, the study's principal investigator put it: "We believe that socially isolated individuals are physiologically different from socially paired individuals."

The full study, "Mechanisms of Neuropathic Pain: Inflammatory Mediators," will be presented at the annual meeting of the Society for Neuroscience.

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