Participants will undergo phone screening, two in-person visits, and telephone follow-up. The first visit will last 4 hours and the second visit will last 10.5 hours. Phone screening and follow-up will take no longer than 30 minutes.~Phone Screening and Visit #1:~Following phone screening to determine potential eligibility, participants will have an in-person evaluation. Following informed consent in the first session, participants will undergo semi-structured clinical interviews and complete questionnaires to assess medical- and medication histories; current- and past history of psychiatric disorders, and evaluation of behavioral symptoms of anxiety and depression. They will also complete computer tasks that assess motivation and sensitivity to reward. As part of one of these tasks, they will be asked to provide a picture of a loved one, which they will later view during a fMRI scan.~Visit #2 and telephone follow-up:~The second session will be about two weeks later. It will begin at 7:30AM and will involve placement of two intravenous catheters (one in each arm), evaluation of heart rate and blood pressure, administration of endotoxin vs. placebo, repeated blood sampling along with questionnaires about mood and symptoms for approximately 10.5 hours. Two hours post-injection participants will complete a 1-hour brain scan that includes tasks to assess motivation and sensitivity to reward. Study staff will escort the participant to a nearby facility to complete the brain scan. 24 hrs and 2-weeks following this session, study staff will call the subject and ask about physical and mood symptoms, using the same set of items used during the experimental protocol.
The purpose of this study is to use an experimental inflammatory challenge to examine whether older adults with symptoms of anxiety experience loss of pleasure or loss of motivation when they are exposed to inflammation. Loss of pleasure or loss of motivation will be evaluated using self-report questionnaires, computer tasks, and during a brain scan.