Dopamine Response to Ultraviolet Light in Frequent and Infrequent Tanners

UV radiation has recently been classified as a known human carcinogen by the US Department of Health and Human Services. Nevertheless, the voluntary exposure to sunlight continues unabated despite progressively increasing rates of ultraviolet radiation (UVR)-induced illness and death, particularly skin cancer. An increasingly common form of UVR administration is through the use of indoor tanning salons. Almost 30 million Americans, including 20% of 18-39 year olds, visit indoor tanning salons each year. Frequent and excessive tanning, despite a growing understanding by those who tan of the morbidity and mortality associated with tanning, suggests that UVR may impart rewarding effects beyond the assumed cosmetic benefits. Recent studies, in fact, have shown that up to 40% of both frequent beach and salon tanners exhibit signs and symptoms consistent with an addictive disorder, including an inability to decrease their tanning frequencies, compulsive tanning, and/or continued tanning despite adverse consequences. As the mesostriatal dopaminergic pathway plays a key role in reward and addiction, the investigators propose to extend this novel finding by directly assessing the mesostriatal dopaminergic reward pathway in compulsive and infrequent tanners. This pathway plays a key role in the experience and integration of reward and alterations in this system have been observed in addicted populations. Specifically, 1) striatal dopamine is released in response to rewarding substances and experiences, 2) striatal dopamine2/3 receptor densities are lower in cocaine, alcohol, opioid, and nicotine dependent, as well as obese, subjects, and 3) reward-induced striatal dopamine efflux has been shown to be decreased in addicted, relative to non-addicted, subjects.