I remember being amazed by my uncle. He has arthritis in his knees and as a small child I was fascinated by his ‘psychic knees’. And by ‘psychic’ I am really describing the situation where he would look at me and knowingly state, “It’s going to rain…my knees are aching.” And then it would! How did his knees know? What aspects of weather could possibly be influencing his knees? Pressure? Humidity? Overall temperature? The dreary knowledge that if it rains he won’t get the crops in?
My uncle certainly isn’t alone. It’s estimated that anywhere from 50-100% of people with a painful condition report that their pain is influenced by the weather (1,2,3) – particularly changes in the weather. Some people report that their pain increases prior to a weather change, some report pain increases during a weather change, and some after. So if so many people report it, it must exist, right? Well, that is what Gier Smedslund and Kare Hagen aimed to find out. They recently published a systematic review that evaluated the relationship between weather (atmospheric and solar variables) and pain reports in people with rheumatoid arthritis.(4) They did loads of searching, lots of reading, and plenty of discussing and came up with 9 studies that met their eligibility criteria.
Their results were surprising to say the least. Despite heaps of anecdotal evidence supporting the relationship between pain and atmospheric variables, at the group level, there was no relationship at all between reported pain and the weather. This included pooling data from numerous studies for the variables of temperature, relative humidity, and for atmospheric pressure. There were 2 studies in the review(5,6) that analysed data at an individual level and they found that 16% and 11% of participants had increased pain with changes in temperature (some with increased temperatue, some with decreased) and 6% and 11% of participants were sensitive to changes in relative humidity (again, some sensitive to increased humidity and vice versa). These percentages are still miles away from the 60-100% of people who say their pain is affected by the weather!
So what could explain these results? Well, the authors provide some possible alternatives and I’ve added a few of my own.
First, there were some limitations to the included studies in the review – it was unclear in pretty much all the studies whether the atmospheric readouts (while great because they are standardised around the world) were measured at the same time as pain. Or should pain have been measured before and after? Further, it is also unclear how close (physically) or how relevant the recorded weather variables were to where the participants actually lived or to what they actually do in a day (ie, did they even go outside or did they stay in a temperature controlled house).
Second, is it possible that the variability in individual responses to the same weather variable (ie, some people have more pain with increased temperature and vice versa) cancelled each other out in the group level analyses, resulting in little to no correlation between weather and pain?
Or third, is our anecdotal evidence that pain is related to weather actually capturing something else? Perhaps we are falling under the trickery of cognitive mis-attribution (ie, we believe that pain is related to rain, so that we really take notice of all days where the pain has increased and it is raining but we tend to forget those days where we have an increase in pain but it is not raining)? Or perhaps it is mood-related. Is it the combination of weather change plus a bad mood or negative affect that is causing the increase in pain? Last, perhaps it is bio-physiological (not to be confused with bio-psychosocial). Is there something physiologically that is occurring during weather changes?
The authors identify a couple of studies that evaluate pain following controlled changes in temperature, humidity, and pressure using a controlled-climate chamber.(7,8) I would be fascinated to see more research in this area. Perhaps include some manipulations of patient expectation, some sham changes in atmospheric variables, and some manipulation of mood and affect, all while we directly control the ‘weather conditions’. It’s always nice to round out the physiological response data before we throw a theory away.
At the end of the day, based on this review, there is no evidence that changes in atmospheric variables influence pain in rheumatoid arthritis. However, I’m a little hesitant to tell that to my uncle’s ‘psychic knees’ before I know a little more.
Tasha Stanton is a postdoctoral research fellow working with the Body in Mind Research Group both in Adelaide (at University of South Australia) and in Sydney (at Neuroscience Research Australia). Tash has done a bit of hopping around in her career, from studying physio in her undergrad, to spinal biomechanics in her Master’s, to clinical epidemiology in her PhD, and now to clinical neuroscience in her postdoc. Amazingly, there has been a common thread through all this hopping and that common thread is pain. What is pain? Why do we have it? And why doesn’t it go away? Tasha got herself one of the very competitive Canadian IHR post-doctoral fellowships and is establishing her own line of very interesting investigations. Her research interests lie in understanding the neuroscience behind pain and its clinical implications. She also really likes nifty experiments that may have no clinical value yet, but whose coolness factor tops the charts. Last, Tash is a bit mad about running, enjoying a good red with friends and organizing theme parties. Tasha, aka Stanton Deliver, was the all round best performer at the Inaugural BiM Table Tennis Comp.
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4. Smedslund, G., & Hagen, K. (2011). Does rain really cause pain? A systematic review of the associations between weather factors and severity of pain in people with rheumatoid arthritis European Journal of Pain, 15 (1), 5-10 DOI: 10.1016/j.ejpain.2010.05.003
5. Dequeker J, & Wuestenraed L (1986). The effect of biometeorological factors on Ritchie articular index and pain in rheumatoid arthritis. Scandinavian journal of rheumatology, 15 (3), 280-4 PMID: 3798044
Smedslund, G., Mowinckel, P., Heiberg, T., Kvien, T., & Hagen, K. (2009). Does the weather really matter? A cohort study of influences of weather and solar conditions on daily variations of joint pain in patients with rheumatoid arthritis Arthritis & Rheumatism, 61 (9), 1243-1247 DOI: 10.1002/art.24729
7. Hollander JL. The controlled-climate chamber for the study of the effects of meteorological changes on human diseases. Trans NY Acad Sci 1961;24:167-72.
8. Hollander JL, Yeostros S. The effect of simultaneous variations of humidity and barometric pressure on arthritis. Bull Am Meteorol Soc 1963;44:489-94.