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There is a long-standing belief among anaesthsetists that people with red hair need more anaesthetic. There even appears to be some evidence. to back up this widely held idea.

Recently, though, a different study (reported by Gizmodo here) has suggested the opposite: that redheads are less sensitive to some types of pain. As they report

It turns out that gingers are less sensitive to stinging pain in the skin, according to researchers who injected capsicum, the active ingredient in chilies, into the arms of patients.

It may be that the experiments looked at different types of pain but both seemed to conclude that redheads are different. So, are they? Are the studies reliable enough to come to trustworthy conclusions? Are there other studies that support the findings?

  • What I wonder is where the idea originated, that red-haired people are different from the rest of the world? – Vilx- Aug 14 '12 at 21:49
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    @Vilx- Most likely it stems from the relative rarity (barring a vitamin deficiency) of red hair in most non-Anglo populations. The rare must be even more special is practically an archetype at this point. It's a conflation of correlation and causation historically. – Aarthi Aug 14 '12 at 22:00
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    You have to think logically here, red heads are red like peppers so they obviously have some type of immunity to capricorns. – SSpoke Sep 17 '12 at 17:09
  • I find the use of the word 'Ginger' to be offensive. – Chris Cudmore Sep 17 '12 at 18:00
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    @matt_black: See youtube.com/watch?v=WLLYO8Hd_sE – Joel Rein Sep 18 '12 at 0:07
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Answer

This scientific article states that a mutation in the MC1R (which is what causes red hair) can also cause some sort of pain reduction, as well as a lesser sensitivity to anaesthetics.

Results: C57BL/6-Mc1re/e mutant mice and human redheads—both with non-functional MC1Rs—display reduced sensitivity to noxious stimuli and increased analgesic responsiveness to the µ-opioid selective morphine metabolite, M6G. In both species the differential analgesia is likely due to pharmacodynamic factors, as plasma levels of M6G are similar across genotype.

However, this report adds that redheads were more sensitive to thermal pain, while less responsive to the common anaesthetic lidocaine.

Results: Current perception, pain perception, and pain tolerance thresholds were similar in the red-haired and dark-haired women at 2000, 250, and 5 Hz. In contrast, redheads were more sensitive to cold pain perception (22.6°C [15.1, 26.1] vs. 12.6°C [0, 20], P=0.004), cold pain tolerance (6.0°C [0, 9.7] vs. 0.0°C [0.0, 2.0], P=0.001), and heat pain (46.3°C [45.7, 47.5] vs. 47.7°C [46.6, 48.7], P=0.009). Subcutaneous, lidocaine was significantly less effective in redheads, e.g., pain tolerance threshold at 2000 Hz stimulation in redheads was 11.0 mA [8.5, 16.5] vs. >20.0 mA [14.5, >20] in others, P=0.005)

Additionally, this article states that redheads are significantly less sensitive to the anaesthetic desflurane.

The desflurane requirement in redheads (6.2 volume-percent [95% CI, 5.9 - 6.5]) was significantly greater than in dark-haired women (5.2 volume-percent [4.9 – 5.5], P = 0.0004). Nine of 10 redheads were either homozygous or compound heterozygotes for mutations on the melanocortin-1 receptor gene.

Lastly, this Wikipedia article explains...

These observations suggests a role for mammalian MC1R outside the pigment cell, though the exact mechanism through which the protein can modulate pain sensation is not known.

In summary: Redheads do appear to be less responsive to general anaesthetics, as far as reported. However, either an increase and/or decrease to different types of painful stimuli is shown. Also, the mechanism for these results is still unknown, but is very probably related to the mutation in the MC1R which gives redheads their red hair in the first place.

Note: All added emphasis is my own.


References

  • Mogil, J, J Ritchie, S Smith, K Strasburg, L Kaplan, M Wallace, R Romberg, et al. “Melanocortin-1 Receptor Gene Variants Affect Pain and Μ-opioid Analgesia in Mice and Humans.” Journal of Medical Genetics 42, no. 7 (July 2005): 583–587.

  • Liem, Edwin B., Teresa V. Joiner, Kentaro Tsueda, and Daniel I. Sessler. “Increased Sensitivity to Thermal Pain and Reduced Subcutaneous Lidocaine Efficacy in Redheads.” Anesthesiology 102, no. 3 (March 2005): 509–514.

  • Liem, Edwin B., Chun–Ming Lin, Mohammad–Irfan Suleman, Anthony G. Doufas, Ronald G. Gregg, Jacqueline M. Veauthier, Gary Loyd, and Daniel I. Sessler. “Anesthetic Requirement Is Increased in Redheads.” Anesthesiology 101, no. 2 (August 2004): 279–283.

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    OMG my dad is the mutant I thought he was growing up :P – Chad Aug 15 '12 at 1:46
  • This answer really surprised me. I did NOT think that this is what I was going to be posting until I did some research. Immediately after I answered, I though of every redhead I knew, and sent them the link ahah :). – LanceLafontaine Aug 15 '12 at 1:53
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    Charles Xavier mentions the mutated MC1R gene in "X-Men: First Class" when he notices Moira's auburn hair ;) – Oliver_C Aug 15 '12 at 8:12
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    Funny how people get so funny about knowing they (or someone they know) have a mutation. Every one of us has lots, there is nothing weird about it. – nico Sep 16 '12 at 19:33

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