Steps toward new medication for women’s arthritis pain
Anyone who lives with arthritis knows that there can be many types of arthritis pain, and sometimes treatments that work for one kind of pain won’t work for another. Dr. Jason McDougall, a professor in the Department of Pharmacology and the Department of Anesthesia, Pain Management and Perioperative Medicine at Dalhousie University in Nova Scotia and PhD student Melissa O’Brien have been leading a research team to learn more about why women and men living with arthritis can have different experiences with pain.
What is nerve pain?
Joint inflammation is not the only source of arthritis pain. Some people living with osteoarthritis (OA) or rheumatoid arthritis (RA) also have neuropathic pain. “It’s a particular type of pain where there’s damage to the actual nerves themselves. This can lead to abnormal firing of these nerves, resulting in a type of pain that’s like a stabbing, pins-and-needles type of pain,” explains Dr. McDougall. “The numbers vary but typically about 30 to 40% of patients have a neuropathic pain component to their disease.”
Dr. McDougall and his team are interested in learning more about differences in neuropathic pain based on sex assigned at birth. “Females are more likely to develop arthritis, and females are more prone to neuropathic pain, so there’s a much greater need, I think, to try and address the sex differences in what’s contributing to arthritic pain,” he says.
Why can women have a different arthritis pain experience?
Sex hormones do play a role in pain, but their exact impact remains unclear. “Some studies show that the female sex hormones can be very neuroprotective and prevent neuropathic pain, but there are other studies showing that in neuropathic pain conditions, the female sex hormones can actually be contributing to that type of pain,” he says. “When we talk about sex differences, it’s an easy go-to to talk about the sex hormones, but there must be many other contributing factors responsible for these sexual differences. We don’t know what they are yet.” Other studies also suggest that women respond differently to pain medication than men.
Treating neuropathic pain
Anti-inflammatory medications such as ibuprofen can work well on pain related to inflammation, but aren’t effective on neuropathic pain. Currently, there are medications used to treat neuropathic pain related to diabetes and multiple sclerosis. “We’ve done some preliminary studies using some of these drugs and applying them to arthritis models and found them to be quite effective in reducing joint pain as well,” notes Dr. McDougall.
In a study published in the medical journal Pain in 2019 involving research on lab rats, Dr. McDougall and his colleagues found that nerve damage in the rats’ knee joints impacted females and males differently. Females also experienced more neuropathic pain. Additionally, treatment with a drug that blocks neuropathic pain signals showed that it was more effective in females. The research is ongoing, but it’s an important step in researching new drug therapies that will target the neuropathic component of arthritis pain. “The drugs that we’ve used so far are really quite short-lasting, so now we’re trying to develop something like an antibody approach where we can target this pathway and get weeks or months of pain relief out of it,” says Dr. McDougall. “Hopefully in the future it will be valuable for patients living with arthritis.”
This research was supported by a Strategic Operating Grant to Dr. Jason McDougall active from 2018-20 and a Graduate PhD Salary Award to Melissa O’Brien active from 2017-18.