The objective of this study is to examine the cognitive, immunological, and neurophysiological effects of transitioning from tobacco cigarettes to electronic cigarettes. The central hypothesis of this study is that this transition will be accompanied by a decrease in peripheral inflammation, which will lead to significant changes in the neurocircuitry underlying interoception and appetite.

Participants who are current cigarette smokers will be randomly assigned to either the experimental or control groups. Following a baseline psychiatric assessment session, subjects will return to the study center for two to three additional follow-up visits.

During the second visit, all subjects will undergo a functional magnetic resonance imaging (fMRI) scanning session, during which they will perform a series of functional neuroimaging tasks designed to examine the neural substrates involved in visceral interoception and eating behavior. Prior to the start of the scan session, blood samples will be collected from each subject, for the measurement of bio-markers related to nicotine use and peripheral inflammation. After the end of the second visit, subjects within the experimental group will be asked to switch from combustible to electronic cigarettes. Subjects within the control group will continue to smoke combustible cigarettes as previously.

During the third visit, which will follow two to eight weeks after the second visit, all subjects will provide a second blood sample and complete a second fMRI scan session. Both groups of participants will complete the same fMRI tasks as they did during the second visit.

Inclusion Criteria:

• current cigarette smokers who have smoked for at least one year
• right-handed adults
• able to provide written informed consent

Exclusion Criteria:

• use of anticonvulsant, stimulant, or antipsychotic medication for 3 weeks prior to scanning
• any medical conditions or medications likely to influence cerebral blood flow or neurological function including cardiovascular, respiratory, endocrine and neurological diseases
• any history of drug (other than nicotine) or alcohol abuse within 1 year
• current pregnancy or breast feeding
• primary language other than English
• meeting general MRI exclusion criteria such as magnetic implants or claustrophobia
• Past history of any axis I psychiatric condition, other than major depressive disorder and post-traumatic stress disorder
• Current major depression or post-traumatic stress disorder
• Serious suicidal ideation