A study from the Yale School of Medicine published in Experimental Dermatology compared 79 individuals with “tanning dependence” – people who are essentially addicted to tanning (for example continuing to tan despite skin cancer) – with 213 individuals who tan recreationally but who are not addicted. They found that people with tanning dependence were more likely to have a unique gene – the “patched domain containing 2” (PTCHD2) gene. The protein product of this gene is found throughout the brain, but scientists have yet to describe its exact function. You can read the full study here: http://onlinelibrary.wiley.com/doi/10.1111/exd.12503/pdf.
Another article in Archives of Dermatology from the University of Texas in Galveston describes this subset of patients whose tanning closely resembles alcohol abuse, applying the DSM-IV criteria for alcohol dependence to UV light dependence. With growing rates of skin cancer secondary to excessive tanning, this under-recognized addiction may have significant public health implications: http://archderm.jamanetwork.com/article.aspx?articleid=398011.
Daily Dermatology 