Valérie Lannoy - Postdoctoral Fellow in Microbiology, Sorbonne University
Our elders sometimes act like weather stations! Thanks to their joint pain, they can predict the day's weather. But is there any truth to this?
Illustration image Pixabay
Rheumatism includes about
200 diseases that affect the components of joints, such as bone and joint cartilage. They also impact the soft tissues, like ligaments on the bones or tendons connecting muscles to bones.
These are classified based on their origin into non-inflammatory and inflammatory rheumatisms. The first group includes osteoarthritis and osteoporosis, which mainly affect elderly individuals, as well as musculoskeletal disorders or fibromyalgia. Inflammatory rheumatisms include types of arthritis, such as ankylosing spondylitis and rheumatoid arthritis, both autoimmune diseases. Today, over
16 million French people suffer from rheumatism.
Rain or humidity?
In 2019, a
team from the University of Manchester studied the symptoms of more than 2,500 patients over 15 months. Several conditions were represented, such as osteoarthritis, rheumatoid arthritis, and fibromyalgia. The symptoms were recorded via a smartphone app, capturing information that included weather, mood, and physical activity. It was one of the first participative science experiments to utilize an app.
The authors suggest that such tools can be offered to patients to anticipate their pain. They found that relative humidity, meaning the saturation of air with water vapor, and atmospheric pressure were most strongly correlated with joint pain.
This correlation, though significant, remains modest. For instance, simultaneous changes in the two meteorological variables lead to only a slight increase in pain. Three years later, a team from the same university decided to
reanalyze the same data. They determined that there is indeed a link between climate and joint pain, but it affects only about 4% of the participants. These researchers explain that pain is subjective and encoded by the brain, meaning individual reactions vary based on differences in neural activation among patients.
The joint as a barometer
The link between joint pain and weather is a topic of heated debates among scientists! In 2017, an
international collaboration led by Dr. Jena analyzed symptoms from about 1.5 million Americans over the age of 65. Their conclusion was that there is no correlation between joint pain and rainy days. Four days later, the
response to this scientific article was swift! Here's how Dr. Bamji, a retired rheumatologist, began his reply: "The reason Dr. Jena and his colleagues failed to find a link between joint pain and rain is simple. They looked at the wrong variable—and as far as I know, no one has considered the correct one."
How could rain or relative humidity influence patients' pain when our body does not have a mechanism to detect fluctuations in humidity levels? Dr. Bamji specifies that the joint is a structure enabling proprioception or deep sensitivity. This is the ability, whether conscious or unconscious, to perceive the position of body parts without using vision. Tendons contain
"proprioceptors", which are receptors sensitive to pressure induced by muscle contraction. Proprioceptors are also sensitive to changes in atmospheric pressure.
Atmospheric pressure actually follows the variations in relative humidity. As for proprioceptors, they transmit their signals via sensory nerves that travel to the brain.
Joint pain is directly linked to atmospheric pressure and indirectly to relative humidity. Each patient's experience depends on their own central nervous system. The most important thing is to listen to your pain, for example, by keeping a daily journal of symptoms.