National report — Ultraviolet radiation from a tanning bed appears to stimulate reward pathways in the brains of frequent tanners, similar to the response seen with other pleasurable stimuli such as food, sex and illicit drugs, according to a recent study.

The work was inspired by a dermatology resident, Cynthia Harrington, who was "concerned with patients who tan frequently and show up with basal cell carcinoma, but after they are treated go out and tan again," says Bryon Adinoff, M.D., an addiction researcher at the University of Texas Southwestern Medical Center, Dallas, and senior author of the paper.

The pilot study recruited seven "frequent tanners" who had used sunbeds at least twice a week during the previous 90 days and met other criteria. Subjects used the same bed twice — once with normal exposure to UV radiation (UVR) and once when a filter was used to block UVR.

The order was randomized to the patients, with at least two days between each session.

Brain activity — cerebral blood flow, which highly correlates with neuronal activity and energy utilization — was measured by single-photon emission computed tomography (SPECT), Dr. Adinoff says.

Radioisotopes were injected into the subjects at the beginning of each tanning session. These isotopes "go up into the brain and are taken up very quickly, within a minute or two," Dr. Adinoff says. "The isotopes stay in the brain and don't wash out, so 90 minutes later you put the subject in the SPECT scan and take a picture. It enables us to essentially trap a picture of the blood flow while they are under the UV light, but we don't have to take the camera image until 90 minutes later."

The scans found a relative increase in cerebral blood flow in areas of the brain associated with rewards — the dorsal striatum, anterior insula and medial orbitofrontal cortex. This strongly suggests that frequent tanners experienced positive stimulus from their UVR exposure that reinforced the desire to tan.

Subjects also were asked before and after the UVR exposure how much they desired to tan. "Their desire went down when they received UVR, but it stayed high when they got the fake light," Dr. Adinoff says. "And it didn't matter whether they received the real light during the first session or second."