Real-world Momentary Assessment of Kratom Use Accompanied by Product Assays: A Natural-history Study for Interdisciplinary Characterization of Kratom Use and Pharmacology

Background: Mitragyna speciosa, also called kratom, is a plant used in Southeast Asia for its psychoactive effects. Its use has increased in the US, and an estimated 10 million adults may take it at least semiregularly. Most scientific research on human use of kratom has consisted of surveys in which people looked back on their experiences with it. Results from those surveys have been useful, but, like many behaviors, kratom use can be more fully understood if it is also studied as it happens. The technical term for this procedure is ecological momentary assessment (EMA). In EMA, people report their moods and activities in real time, a few times per day, usually with a smartphone app. Objective: This natural history study will collect data about how people use kratom and how it affects them. Eligibility: People aged 18 and older who use kratom 3 or more times per week Design: Most participants will be remote only. They will fill out an online consent form. They will also answer an initial set of questions about their kratom use. They will download an app on their smartphones for EMA (described above). They will use this app to answer short sets of questions for 15 days in a row about their ongoing behaviors and moods, including kratom use. They will use a prepaid envelope to mail in a sample of their kratom product. Some participants, after doing the EMA part of the study, can also come to a clinic. They will have 1 visit for informed consent (1-3 hours) and 1 visit for a monitoring session (8 hours) where we can directly assess the effects of their usual dose of kratom. They will bring their kratom produce with them to take on site. Before they take the kratom, they will have a physical exam. They will have blood and urine tests. They will answer questions about their sleep, driving, and general feelings. They will complete tasks on a computer to measure their reflexes and response times. Their driving performance will be assessed in a simulator. Resea