Living With Chronic Pain

Gender Impacts Pain Pathways

It had been accepted for decades that men and women experience pain the same way. But this wasn’t based on any scientific proof, especially when all the data came from research on male participants. Women suffer from chronic pain conditions far more than men. For decades this difference led to assumptions that minimized and diminished woman’s pain, often stamping it as “in their heads” and not real. In too many cases this misperception of how men and women feel and express pain had serious consequences, leading to delayed treatment, misdiagnoses and neglect.

Women and men do not experience pain the same way. This was proven the hard way when it was learned over 60% of women do not have chest pain when experiencing a heart attack. According to the American Heart Association, our complaints can be more vague, like upper abdominal, back and/ or jaw pain, shortness of breath, dizziness, fatigue, a generalized feeling “something is off”. As a result, women are far more likely to be sent home with a diagnosis of anxiety or indigestion than cardiac.

Despite clear differences in how pain was reported scientific consensus remained steadfast for decades in their claims men and women were affected by pain equally. The fact women not only experience pain differently than men but actually have a heightened physiological response to pain was finally documented when women were asked to participate in previously all male studies. In double blind studies inducing pain across multiple modalities- mechanical, electrical, chemical- women consistently showed more sensitivity than men.

It turns out we are not equal. A female brain’s immune cells are more active in regions that involve pain processing than those in males. When these cells were blocked, women experienced the same relief men experienced normally with pain medication finally explaining why opioids are less effective in females. But the brain isn’t the only area that’s more sensitized to pain in women. The superficial dorsal horn is a region of gray matter in the spinal cord. In post mortem studies in donated cadavers it was discovered that a specific protein – BDNF ( brain derived neurotrophic factor) plays an important role in how we process pain. Once women were finally added to the mix, it was realized that only men changed the way accessory neurons impacted BDNF and subsequently decreased pain signals. It appears to be hormonally mediated, specifically by estrogen levels since this particular difference disappeared when ovaries were removed in female rats.

From a purely biological perspective women have been shown to perceive pain different than men because:

* There’s a greater density of nerve cells in women not just in the brain, but everywhere in the body. For example women have 34 nerve fibers per square centimeter of facial skin compared to men who only average 17.

* Studies have shown the female body itself is hard wired differently than men causing women to have a more intense response to painful stimuli. Gender affects how long neurons that transmit pain signals survive and the strength of that signal.

*Fluctuating female hormones, particularly estrogen, appear to amplify pain. Receptors for sex hormones are in the same area of the nervous system as those that pick up and transmit pain signals. As hormones levels change during the monthly cycle tissues, muscles and skin become more or less sensitive to pain. Pain levels increase when estrogen levels are low and progesterone levels are high, as they are in the second half of the menstrual cycle. It’s believed there are more “feel good hormones” circulating when estrogen levels are elevated.

*Women have a higher risk of suffering from conditions that cause pain e.g. fibromyalgia, headaches, gastrointestinal complaints, and arthritis, because of their fluctuating hormone levels. After puberty women are 2 to 6 times more likely to suffer from chronic pain. As a result they report pain more frequently than men.

*Female hormones increase inflammation within women unlike testosterone that is an anti-nocioceptive hormone, meaning it blocks or lessens the effects of painful stimuli. Another reason why men experience less severe pain levels than women to the same painful stimuli.

* Testosterone appears to a key player in preventing pain caused by T cells one of two types of lymphocytes and regulators of the immune system. These immune cells can promote chronic pain by releasing pro inflammatory cytokines that regulate pain either through pain seeing nuerons or modulation of nueroinflamation. Without the testerone levels seen in men, T cell inflammation mediated pain is higher in women.

*Testosterone assists opioids in crossing the blood brain barrier and helps to activate a number of central receptors and neurochemical systems. Another reason why targeting brain mediated pain works better in men.

*Testosterone is crucial for cellular growth, immunity and a healthy nervous system. It helps support body composition, bone mass and muscle strength. According to new research low testosterone levels may also increase risk for osteoarthritis and developing rheumatoid arthritis.

*MRI scans show substantial differences in how the central nervous system processes painful stimuli and even the anticipation of pain in women.

*Some data has implied a genetic predisposition to chronic pain. In those with chronic neck, shoulder or back pain after a motor vehicle accident a specific suite of RNA molecules associated with pain has been elevated. Since many of these molecules are encoded by genes on the X chromosome it may mean women have a higher propensity towards chronic pain because we have two.

Men and women are not the same. Each has their own unique responses that impacts how they perceive and feel pain. One is not stronger or weaker than the other. Chronic pain is debilitating. Acknowledging the disparity and increased physiological propensity women have to painful conditions can help medical providers recognize, diagnose and improve treatment plans. It has also encouraged scientists to find more targeted ways to diminish pain.









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