The Effect of Visual Stimuli on Itch Perception Intensity in Healthy and Atopic Dermatitis Patients

Inclusion Criteria: * Adult men and women who are between 18 and 65 years of age * Diagnosis of moderate to severe atopic dermatitis including involvement of the forearm confirmed by published consensus diagnostic criteria35 (except for healthy control subjects). Severity of AD will be based on an investigator's global assessment score (IGA). * Subjects must be in general good health with no other skin disease, disease state or physical condition which would impair evaluation of their skin or which would increase their health risk by study participation * Women of child bearing potential will be required to have a negative pregnancy test in order to enroll in the study and will be required to maintain adequate birth control throughout the study. * All subjects in Groups 1 and 3 will be required to cease use of oral antihistamines for a period of one week prior to and during the study visit. * Subjects in Groups 1 and 3 must cease using topical agents on the forearm where experimentation is going to be performed at least 1 week prior. Topical agents can be used in all other parts of the body. * Baseline COVAS ratings of more than 9/100 after histamine iontophoresis at the screening visit Exclusion Criteria: * Adults over age 65 * Children less than 18 years of age * Unable to complete the required measures * Currently enrolled in any investigational study in which the subject is receiving any type of drug, biologic, or non-drug therapy and subjects undergoing treatment with another investigational drug or approved therapy for investigational use within 28 days prior to study participation * Consumption of more than 4 caffeinated beverages per day * Current treatment with oral lipophilic beta blockers, opioids, glucocorticoids, theophylline, antihistamines or other medications known to interfere with itch perception or heart rate variability as determined by the investigators * Uncontrolled asthma or COPD * Uncontrolled thyroid disease * Poorly controlled diabetes mellitus * Poorly compensated congestive heart failure * Use of illicit drugs * History of chronic urticaria * History of anaphylactic shock * History of neuropathy causing disease such as diabetes and uremia * Allergy to histamine * Blindness * Baseline COVAS ratings of less than 9/100 after histamine iontophoresis at the screening visit * Subject participation in more than one group. * Positive pregnancy test