A Comparison of Scalp Blood Flow and Hair Shaft In Premenopausal Women Versus Postmenopausal Women

Inclusion Criteria: * Must be willing to sign informed consent * Female in age groups 19-25 years old and 60 years or older * Must be of Caucasian descent, to avoid any ethnic differences in hair biology or pigment among different races * Must be willing to have a thorough scalp and hair shaft examination * Must be willing to discuss current and past hair care regimens * Must have washed hair at least 48 hours, but not less than 12 hours prior to study visit * Must be willing to not wash hair between Baseline and second visit. * Pregnant and nursing females will not be allowed in the study; a baseline pregnancy test will be done to exclude pregnancy on females of childbearing potential * Must be \>6 months (26 weeks) postpartum * Must have sufficient contrast between scalp skin color and hair color (Fitzpatrick skin type I-IV) * Must have hair at least 2 inches long * May have mild itching and mild scaling of the scalp, but not dandruff * Must be willing to have hair clipped and shaved to 1 mm within an approximately 1cm2 test site * Must be a non-smoker for the past 6 months * Must be in good stable general health, with no current infections * Must be able to return to the study site 48 hours after the Baseline visit for the second visit. Exclusion Criteria: * Must not have hypertension, diabetes, or any neurological disease since all these can affect scalp blood flow * Must not take any antihistamines for two weeks prior to the baseline visit and throughout the study. * Must not have any known allergy or past history of anaphylaxis to histamine * May not have sewn-in or glued hair pieces or extensions at the time of the study * Must not cut hair during the study * Must not have hair loss beyond what is considered normal in the opinion of the Investigator at the time of the study * Must not color hair or have other salon-type procedures (relaxer, permanent, highlighting, etc.) performed within 2 weeks of the initial visit * Must not have any other underlying scalp disorder that could interfere with the test procedures or findings * Must not have lost ≥10% of body weight within the past 12 months * Must not have been on a weight reduction program overseen by a physician or nutritionist within the past 12 months * Has used hair growth products e.g. minoxidil in the past 18 months * Has undergone a hair transplant or scalp reduction surgery * Has participated in a hair growth study within the past 15 months * Is currently participating in another clinical study at this or any other facility * Is taking, for a chronic condition, any prescription or over the counter medication(s) that in the opinion of the Investigator are likely to affect the hair properties (e.g. immunosuppressive agents, corticosteroids, or chronic use of anti-inflammatory medication) * Application of any over-the-counter or prescription drug to the scalp on a routine basis within the past 3 months including but not limited to retinoids (e.g. retinal, tretinoin, retinylpalmitate, retinyl acetate, retinyl propionate), topical corticosteroids, benzyl peroxide, or any topical hormone therapy (e.g. Eterna 27)