"Addiction" may fuel tanning, risk-taking

Maui – Taken together, two new studies suggest that among teens, indoor tanning is linked with other risky behaviors, and that tanners may be seeking a sort of natural high. This information may help dermatologists discuss healthy living in general with patients.

Recent data reflect a slight downturn in tanning among teenagers, said Hensin Tsao, M.D., Ph.D., at MauiDerm. He is clinical director of the Massachusetts General Hospital (MGH) Melanoma & Pigmented Lesion Center, director of the MGH Melanoma Genetics Program, and professor of dermatology at Harvard Medical School.

A national survey shows that the proportion of teens who had tanned indoors fell from 25.45 to 20.9% between 2009 and 2011.¹ Among the heaviest users, non-Hispanic white females aged 16 years and up, the corresponding figures are 37% and 29%.

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Perhaps more surprising are statistically significant associations that surfaced between indoor tanning and other risky behaviors, such as binge drinking (reported by 31.2% of female tanners and 6.2% of male tanners), unhealthy dieting (27.8% versus 9.3%, respectively) and sexual intercourse (29.6% versus 6.5%). For girls, the data also revealed statistically significant associations between tanning and sunscreen avoidance (24.9%), illegal drug use (28.4%), and having four or more sexual partners (26.6%).

Frequent tanners exhibit even more willingness to take risks, said Dr. Tsao. Among girls who tan more than 10 times yearly, 55% to 65.5% reported sunscreen avoidance, binge drinking, and steroid use without prescriptions.

Overall, Dr. Tsao said that by age 18, "Roughly one-third of all American high school girls probably have tanned. More importantly, there's a chance that patients who routinely tan also regularly engage in unprotected sex, binge drinking, and illicit drug use." And a similar biochemical buzz may drive all these ill-advised behaviors, he surmised.

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In this regard, a mouse study has shown that, with respect to tanning, β-endorphins in the skin may drive addictive behavior.² UV damage to keratinocytes produces hormone products in the skin including the pro-opiomelanocortin (POMC) gene, said Dr. Tsao. Components that split off this peptide include melanocyte-stimulating hormone, which stimulates tanning. "The other component people don't think about is a natural endogenous opiate, β-endorphin. Maybe this secondary product has some more central behavioral influence" than previously recognized.

In the study, UVB-irradiated mice had higher serum β-endorphin levels versus unirradiated mice. Additionally, threshold pressure testing of the skin showed that irradiated mice could tolerate more pressure and heat, suggesting that their skin had been anesthetized – an effect that the opiate antagonist naloxone reversed.

Giving irradiated mice naloxone moreover produced opiate withdrawal symptoms. And when given a choice, irradiated mice avoided water infused with naloxone in favor of pure water. "That's additional evidence that they're somewhat behaviorally addicted."

Although tanning beds provide largely UVA rather than UVB, he said, "The study is intriguing. UVB creates mutations in the skin. Perhaps the genesis of this pathway is sunburn pain."

If tanning is truly a component of global risk-taking behavior, "That has much less to do with mutations in the skin than with the brain's pleasure center." Ultimately, he'd like to see studies showing convincingly that tanners have higher β-endorphin and opiate levels – and then investigating whether opiate antagonists could curb humans' urge to tan.

For now, he said that when counseling patients who tan, dermatologists can consider it an opening to discuss whether they're engaging in other risky behaviors. "Tanning may be an opportunity to open a dialogue about risk behaviors and healthy living overall." That includes eating five servings of fruit or vegetables daily – another healthy habit that tanners in the survey shunned.

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NEXT: REFERENCES & DISCLOSURES

REFERENCES

DISCLOSURES: Dr. Tsao serves on the editorial boards of several dermatology journals and has received research funding from the National Institutes of Health and the American Skin Association.

Physician: Hensin Tsao, M.D., PhD

Phone: 617-726-9569 office, 617-331-3958 cell

E-mail: hensintsao@gmail.com

1.  Guy GP Jr, Berkowitz Z, Tai E, Holman DM, Everett Jones S, Richardson LC. Indoor tanning among high school students in the United States, 2009 and 2011. JAMA Dermatol. 2014;150(5):501-11.

2.  Fell GL, Robinson KC, Mao J, Woolf CJ, Fisher DE. Skin β-endorphin mediates addiction to UV light. Cell. 2014;157(7):1527-34.