Do individuals with red hair require additional anesthesia?

Key Insights

It's already concerning that people with red hair -- or gingers, as our British counterparts refer to them -- might eventually disappear. Now, it's discovered that redheads require more anesthesia than others. A 2002 study by the University of Louisville in Kentucky confirmed what anesthesiologists -- doctors specializing in anesthesia management -- had suspected for years: that redheads are harder to sedate.

At the University of Louisville, researchers selected 20 female participants, aged 19 to 40. Of these, 10 were redheads, and the other 10 were brunettes. The brunettes served as the control group.

The researchers exclusively chose women to eliminate any potential gender biases. Additionally, they ensured that the women’s menstrual cycles were synchronized, as hormonal fluctuations can influence how the body responds to anesthesia.

Each of the 20 women was given desflurane, a commonly used anesthetic gas. Once the anesthesia took effect, the researchers administered electric shocks at a level that would be unbearable for someone awake [source: Medscape]. If the subject still experienced pain, the researchers increased the dose of desflurane and continued administering shocks until there was no response.

The researchers’ results confirmed the long-held belief among anesthesiologists: Redheads require more anesthesia. Specifically, it took an average of 20 percent more to achieve the desired effect.

Anesthesiologists carry out a high-risk job that demands precision. Insufficient anesthesia could cause a patient to awaken during surgery, experiencing pain or recalling the procedure. On the other hand, too much anesthesia could lead to an overdose, potentially causing a coma, or even death.

Although the experiment might seem harsh, it provided valuable insights for anesthesiologists to better treat redheaded patients. The discomfort experienced by the redheads in the University of Louisville study could help reduce pain for countless other redheaded individuals undergoing surgery. This characteristic isn't exclusive to redheaded women, though. A 2004 study found that both redheaded men and women require more anesthesia than their peers [source: Consumer Reports].

Genetics and Pain

It’s a bit unsettling, but medical science still doesn't fully understand how anesthesia works. However, the University of Louisville study has shed some light on the enigmatic processes within the higher brain. If redheads need more anesthesia than others, it likely relates to their genetic makeup. Fortunately, geneticists have already pinpointed the gene causing this anomaly.

The melanocortin-1 receptor (MC1R) gene is responsible for producing pigments in the body. Redheads produce more of the red pigment pheomelanin while producing less of the dark pigment eumelanin. These pigment levels explain why redheads have red hair and are prone to poor tanning.

Beyond this, scientists can only theorize about why this gene might influence pain. One theory is that the MC1R gene may also play a role in producing hormones that activate pain receptors in the brain. The same mutation that affects pigment production might lead to an overproduction of pain-related hormones, making redheads more sensitive to pain.

Another theory proposes that the pigments themselves might directly contribute to heightened pain sensitivity. When the MC1R gene doesn't function properly, the melanin can't bind with its designated receptors, and the pigments may attach to other, similar receptors, like those in the brain that process pain. This improper binding could overstimulate pain responses, explaining why redheads need more anesthesia.

Further studies on mice have also shown a connection between this gene and pain sensitivity. Mice with a mutated MC1R gene and lighter fur colors require more anesthesia to manage pain compared to mice with a functional MC1R gene.

While geneticists are certain the MC1R gene is linked to pain sensitivity, the exact mechanism remains unclear. The University of Louisville's study was the first to link a phenotype (a visible genetic trait) with anesthesia needs. Since the effects of anesthesia on the brain are not fully understood, studying how genes influence these processes could shed light on which brain regions are involved in these functions.

Pharmacogenetics, an emerging field of medicine, is also benefiting from these developments. This relatively new discipline examines how genetic variations influence people's responses to medications. Instead of using a standard, higher dose of anesthesia for individuals with red hair, which increases the risk of overdose, future research in pharmacogenetics might lead to a specialized anesthesia tailored for redheads.