Test-retest Study With [18F]PI-2620 in PSP-RS and NDC

Inclusion Criteria (for all subjects) * Males and females aged 50-80 years * Able to understand, sign and date written informed consent * Signed and dated written informed consent obtained from the subject * The subject has an appropriate caregiver capable of accompanying subject, if necessary * Have an Montreal Cognitive Assessment (MoCa) score ≥ 27 * Female subjects must be documented by medical records or physician's note to be either surgically sterile (by means of hysterectomy, bilateral salpingectomy or bilateral oophorectomy) or post-menopausal for at least 1 year (no menses for 12 months without an alternative medical cause). If they are of child-bearing potential, must commit to use of a highly effective contraceptive measure for the duration of the study * Male subjects and their partners of childbearing potential must commit to the use of a highly effective method of contraception for a minimum of 90 days following each PET scan * Male subjects must commit to not donate sperm for a minimum of 90 days after each PET scan * Willing and able to cooperate with study procedures including lying flat and still on the scanning bed for 60 minutes Inclusion criteria for non-demented controls (NDC) * Healthy with no clinically relevant finding on physical examination at screening * No cognitive impairment from neuropsychological battery as judged by the investigator * A brain MRI without evidence of significant neurological pathology * A beta-amyloid Neuraceq® PET demonstr…