For decades, scientists have known that men and women perceive pain differently, with women often reporting higher sensitivity. As experts in neuroscience, we've followed emerging research closely, and a new study from Canadian researchers at Carleton University sheds light on the biological roots of these sex-based differences.
Chronic pain disproportionately affects women, who are more likely to experience low back pain, orofacial pain, cervical pain, and neuropathic pain compared to men. Women are also twice as likely to suffer from migraines and tension headaches.
Laboratory studies confirm this trend: women exhibit heightened sensitivity to experimentally induced pain across mechanical, electrical, thermal, and chemical stimuli. Potential explanations include greater nerve density in female tissues or hormonal fluctuations that intensify pain signals. Yet, the precise mechanisms have remained elusive.
Published in the journal Brain, research led by Dr. Annemarie Dedek at Carleton University examined nerve receptors in human spinal cord tissue—a critical hub in pain transmission.
The spinal cord acts as an intermediary: sensors in muscles, skin, organs, and joints detect threats and relay signals to it, which then forwards them to the brainstem and brain in milliseconds.
This study stands out for two reasons: it included female subjects and focused on human tissue, addressing gaps in prior male-dominated animal research.
A key player is brain-derived neurotrophic factor (BDNF), a protein in the spinal cord discovered 40 years ago. BDNF amplifies pain signals short-term but dampens them long-term—a role confirmed in earlier studies, mostly on male rodents.
Analyzing spinal cord tissues, the team found BDNF crucial for enhancing pain signals in male humans and rats, but not in females. This confirms that males and females process pain differently at a molecular level.
The researchers concluded: "This sex difference in BDNF response is hormone-mediated." Elevated estrogen in females may drive this, as ovariectomy in female rats eliminated the disparity—aligning with prior hormone-pain links.
This is the first report of sex-based pain signaling differences in human spinal cords. Further studies are essential to fully elucidate these mechanisms.
The findings are significant: most analgesics ignore these differences. They pave the way for targeted therapies that could transform chronic pain management for millions.
