Many Alzheimer’s disease (AD) patients have problems with the blood vessels in the brain. These problems could contribute to the cognitive decline observed in AD. We have been studying the role of a blood-based system called the contact system in AD. This system leads to blood clotting and inflammation, is activated in AD patients and contributes to the severity of disease in mouse models. We will investigate how the contact system contributes to AD pathology using mouse models. A better understanding of the effects of the contact system in AD could help better diagnose which patients have a vascular component in their disease, and help to design novel treatments for these patients.