By Shireene Kalbassi
Edited By Sophie & Monika
When it comes to the recovery of wounds and other medical conditions, most people probably think of hospital beds, antibiotics, and maybe some stitches. What probably doesn’t come to mind is the role that companionship may play in speeding up the healing process.
And yet, studies in humans have shown a link between increased companionship and enhanced recovery prospects (Bae et al 2001, Boden-Albala et al 2005).
So why should it be that social interaction influences the recovery process? Well, in social species, social interaction leads to the release of the hormone known as oxytocin, AKA the “love hormone”. This hormone is released from the pituitary gland, located in the brain. Increased levels of oxytocin have been associated with lower levels of stress response hormones, such as cortisol and corticosterone, and high levels of these stress response hormones have been shown to lead to impaired healing (Padgett et al 1998, DeVries et al 2002, Heinrichs et al 2003, Ebrecht et al 2004).
This link between social interaction, oxytocin, stress hormones and recovery has been explored in studies, such as the work of Detillion et al (2004). Here, the authors investigated how companionship impacts wound healing in stressed and non-stressed hamsters. The role of companionship was explored by comparing socially isolated hamsters to ‘socially housed’ hamsters, that share a home environment with another hamster. Stressed hamsters were physically restrained to induce a stress response, while non-stressed hamsters did not undergo physical restraint.
In order to understand how these factors relate, the authors therefore compared four different groups: hamsters that were socially isolated and stressed, hamsters that were socially housed and stressed, hamsters that were socially isolated and non-stressed, and hamsters that were socially housed and non-stressed.
The hamsters that were socially isolated and stressed showed decreased wound healing and increased cortisol levels, when compared to socially housed hamsters or non-stressed socially isolated hamsters. Furthermore, when a blocker of oxytocin was given to socially housed hamsters decreased wound healing was observed, while supplementing stressed hamsters with oxytocin lead to increased wound healing and lower levels of cortisol.
So it seems that when social animals interact oxytocin is released, which reduces the levels of stress hormones, leading to increased wound healing.
But what if there is more to the story than this? These studies, and others like it, demonstrate a relationship between companionship and wound healing, but how might factors relating to social interaction impact recovery?
Venna et al (2014) explored the recovery of mice that were given a brain occlusion, where part of the blood supply of the brain is shut off to try to replicate the damage seen in stroke. However, in this study the mice were either socially isolated, paired with another stroke mouse, or paired with a healthy partner. When assessing recovery, the authors looked at multiple parameters including death rates, recovery of movement, and new neuron growth. The authors observed that, as expected, socially isolated stroke mice showed the lowest rates of recovery. Interestingly, stroke mice that were housed with other stroke mice showed decreased recovery rates when compared to stroke mice that were housed with a healthy partner.
So why should the health status of the partner influence the healing process of the mice? The work of Venna et al did not assess if the amount of social contact between stroke mice that were housed with another stroke mouse was equal to that of stroke mice that were housed with a healthy partner, which may explain the discrepancy seen between the two groups. Exploration of this could lead to better understanding of whether the quantity of social interaction may be leading to decreased recovery rates in the stroke mice housed with other stroke mice groups, or if the decreased recovery may be due to other factors.
Regardless, it appears that social interaction may not be a simple box to tick when it comes to enhancing the recovery process but is instead dynamic in nature. And while nothing can replace proper medical care and attention, companionship may have a role in speeding up the recovery process.
If you want to know more about the use of animals in research, please click here.
Bae, S.C., Hashimoto, H.I.D.E.K.I., Karlson, E.W., Liang, M.H. and Daltroy, L.H., 2001. Variable effects of social support by race, economic status, and disease activity in systemic lupus erythematosus. The Journal of Rheumatology, 28(6), pp.1245-125
Boden-Albala, B., Litwak, E., Elkind, M.S.V., Rundek, T. and Sacco, R.L., 2005. Social isolation and outcomes post stroke. Neurology, 64(11), pp.1888-1892
Padgett, D.A., Marucha, P.T. and Sheridan, J.F., 1998. Restraint stress slows cutaneous wound healing in mice. Brain, behavior, and immunity, 12(1), pp.64-73.
DeVries, A.C., 2002. Interaction among social environment, the hypothalamic–pituitary–adrenal axis, and behavior. Hormones and Behavior, 41(4), pp.405-413.
Heinrichs, M., Baumgartner, T., Kirschbaum, C. and Ehlert, U., 2003. Social support and oxytocin interact to suppress cortisol and subjective responses to psychosocial stress. Biological psychiatry, 54(12), pp.1389-1398.
Ebrecht, M., Hextall, J., Kirtley, L.G., Taylor, A., Dyson, M. and Weinman, J., 2004. Perceived stress and cortisol levels predict speed of wound healing in healthy male adults. Psychoneuroendocrinology, 29(6), pp.798-809.
Detillion, C.E., Craft, T.K., Glasper, E.R., Prendergast, B.J. and DeVries, A.C., 2004. Social facilitation of wound healing. Psychoneuroendocrinology, 29(8), pp.1004-1011.
Glasper, E.R. and DeVries, A.C., 2005. Social structure influences effects of pair-housing on wound healing. Brain, behavior, and immunity, 19(1), pp.61-68
Venna, V.R., Xu, Y., Doran, S.J., Patrizz, A. and McCullough, L.D., 2014. Social interaction plays a critical role in neurogenesis and recovery after stroke. Translational psychiatry, 4(1), p.e351