History of myocardial infarction, angina pectoris, sustained or episodic cardiac arrhythmias, symptomatic peripheral vascular disease, current peptic ulcer disease or any other medical condition which the physician investigator deems inappropriate for subject participation. Insulin-dependent diabetes. Pregnant or lactating, or not using adequate birth control methods. Requirement of any form of regular psychotropic medication (antidepressants, antipsychotics, or anxiolytics) and recent psychiatric history (less than 1yr). Chronic use of systemic steroids or antihistamines. Abuse of alcohol or any other recreation aor prescription drug (more tha 3 drinks per day or 21 drinks per week). Use of any other nicotine products, including smokeless tobacco, cigars and nicotine replacement products. Inability to fulfill all scheduled visits and examination procedures throughout the study period. History of schizophrenia or manic depressive disorder. Recent history of other psychiatric illness;less than 1 year since last episode of major depressive episode.