New research on obesity and chronic pain in adolescents uncovers sex differences with troubling implications for female teenagers with these conditions. The researchers will present their findings virtually at the American Physiological Society's (APS) New Trends in Sex and Gender Medicine conference.
Over 21% of those ages 12–19 in the U.S. have obesity. The U.S. Centers for Disease Control and Prevention has described obesity among children and adolescents as a serious problem. Similarly, chronic pain affects an estimated one-fourth to one-third of children and adolescents worldwide, prompting the World Health Organization to consider it a major health concern among children and teenagers.
Obesity both exacerbates pain and hinders its treatment. Conversely, chronic pain is a barrier to exercise and can affect treatment of obesity. Obesity and pain also independently act on the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is an important part of the body's stress response because, among other things, it stimulates the release of the hormone cortisol. Cortisol affects functions throughout the body, including metabolism of glucose, fat and protein, and can act as an immunosuppressant and anti-inflammatory. Because of cortisol's anti-inflammatory action and effects on the central nervous system, the team said it "would be expected to alleviate pain."
The research team took blood samples from 144 teenagers between the ages of 13 and 17, breaking males and females each into four categories: average weight without chronic pain (controls), average weight with chronic pain, obese without chronic pain and obese with chronic pain. They then measured the amount of cortisol in the subjects' blood.
Though males with chronic pain had no difference in their cortisol levels compared to the male control group, males with both obesity and chronic pain had lower cortisol than obese males without pain. Female controls had significantly more cortisol than male controls. All three other female groups showed dramatically decreased cortisol, with obese females lower than females with chronic pain, and females with both obesity and chronic pain the least of all.
This chronic decrease in cortisol in the female subjects could account for sex differences in chronic pain and its response to treatment, researchers said.