About 380 males and females aged 55 to 90 years with psychosis associated with Alzheimer's disease will take part in this worldwide study. This study will be conducted at up to 100 sites in the United States, Canada, France, Germany, Spain and others in approximately 10 countries. The study will test KarXT, a combination of 2 study drugs, xanomeline tartrate and trospium chloride. Xanomeline tartrate stimulates the muscarinic receptors (a receptor in the nervous system) that is involved in cognitive and neurobehavioral functions. Stimulation of these receptors has been shown to effect changes in cognitive performance and promote antipsychotic activity. Trospium chloride is a muscarinic inhibitor that is expected to reduce the negative peripheral (outside the brain) muscarinic side effects of xanomeline tartrate without reducing its intended therapeutic effects in the brain.
The goal of this study is to assess whether KarXT helps in relapse prevention in people with psychosis associated with AD as compared to placebo, see how safe and well accepted KarXT is in people with psychosis associated with AD as compared to placebo, and check what the body does to KarXT and how long does it stay in the body (pharmacokinetics) as compared to placebo.

The purpose of the Alzheimer's Disease Registry Study (ADRS) is to (1) create a registry that will continue to provide study-ready subjects who meet research diagnostic criteria for the different stages of AD and who have been evaluated using research instruments that allow for their participation in clinical trial research, (2) provide a platform to allow for continual follow-up with registry participants to allow for their participation in clinical trial research at different stages of the disease process, and (3) to incorporate a population of veterans and minorities suffering from AD, a population that is not proportionally represented in clinical trial research, into the registry.

By collecting data pertaining to medical history, current medication details, family history, vital signs, and memory/thinking symptom concerns and evaluating a subject's ability to perform certain tasks, such as memory and thinking tests, questions about their daily activities, and social functioning; researchers are able to determine a research subject's potential eligibility in a clinical trial research protocol.

A registry with such information would enable researchers to effectively and efficiently identify potentially eligible research subjects for the program's evolving portfolio of Alzheimer's disease-related clinical trials.

With this research study, we want to learn if methylphenidate (Ritalin® and others) helps people with Alzheimer's disease and apathy (lack of interest or concern for things that others find moving or exciting).