Olfactory Function and Model-Based Behavior in People Living With HIV and SUD

Background: Human immunodeficiency virus (HIV) infection can affect areas of the brain that control thinking ability. These same areas of the brain also control the sense of smell. HIV infection is common in people with substance use disorder (SUD). SUD also affects thinking ability. Researchers want to learn more about the connection between the sense of smell and decision-making ability in people with HIV, SUD, or both. Objective: To test the sense of smell in people with HIV and/or SUD and how they make choices based on odors. Eligibility: People aged 18 to 65 years with any of these: (1) HIV, (2) SUD, (3) both HIV and SUD, or (4) neither SUD nor HIV. Design: Participants will have 2 visits. Each visit will last 3 to 5 hours. In visit 1, participants will have a blood draw and a saliva swab. They will answer questions about their health, sleep habits, food intake, and substance use. They will have smell tests: They will smell scented sticks and answer questions about them. They will be blindfolded for some tests. They will perform tasks on a computer. They will look at pictures and smell pleasant food odors, such as chocolate cake or pizza. Smells will be delivered using a nasal mask. Their sniffing and breathing will be measured. They may also be exposed to odor-free air. They will eat food that corresponds to one of the food odors they smelled. In visit 2, participants will do a saliva swab and a different computer task that involves odors. They will also have tests of their attention and memory. Participants may opt to have an imaging scan of the brain.