Dopamine Response to Ultraviolet Light in Frequent and Infrequent Tanners
The overall goal of this study is to determine if uVR induces striatal dopaminergic efflux and if basal D2/D3 receptors and uVR-induced dopamine efflux is altered in compulsive tanners. Two groups will be tested: a group of frequent, compulsive salon bed tanners and a group of age-, sex-, and skin-phototype matched infrequent tanners. Subjects will be studied under two conditions on two separate days: (1) tanning under a commercially available tanning canopy ([Quote]active uVR[Quote]), and (2) lying under the same canopy with a uVR-filter in place ([Quote]sham uVR[Quote]). The filter allows the visible spectrum of light and heat to come through but blocks uVa and uVB light. Basal D2/D3 receptors and uVR-induced dopamine efflux will be assessed by using 123i-iBZM binding potential (BP) and Single Photon emission Computerized Tomography (SPeCT).
* Age: 18-45 years old. As tanning frequency dramatically decreases in subjects over 40 years old (5, 6, 27) and limit variability, only subjects 18-45 y/o will be included. Men and women will be studied.
* Subjects with Fitzpatrick skin type II-V will be included regardless of ethnicity or race (see Section III.B.1). Tanning for skin type I (pale white) is not recommended due to likelihood of burning. Tanning in skin type VI (dark brown or black skin) is unusual due to ineffectiveness. Inclusion of skin type II-V is expected to include more than 90% of tanners (6, 27).
* Subjects report tanning at least two times weekly over the previous year. (The typical tanning interval for frequent tanners is 2-3 times weekly.) At least 50% of the tanning episodes will be in an indoor tanning bed. (Many compulsive tanners tan outside during the summer months).
Infrequent tanners will be included as a comparison group. Familiarity with the salon tanning experience, without the compulsive use, offers a more appropriate comparison group than a tanning-naive group. This is similar to studying occasional drinkers or gamblers as comparison groups for alcohol-dependent subjects (30, 31) or pathological gamblers (32), respectively, to assess reward and craving mechanisms.
* Similar age, gender, and race/ethnic criteria as for Compulsive Tanners. Infrequent tanners will be recruited to match age, gender, and skin phototype distributions with Compulsive Tanners.
* Reports at least ten lifetime episodes of use of a tanning bed. This will assure familiarity with tanning bed environment.