RecruitingDrug trialInvestigation of Inflammation in Alzheimer's Disease and Related Dementias (ADRD) Using [11C]-CS1P1This study involves a brain positron emission tomography (PET) scan with a new, investigational radioactive tracer called \[11C\]-CS1P1 to identify inflammation in the brain by testing with healthy older adults and with cognitively impaired older adults.