Tau Imaging in Young Onset Dementia

Inclusion Criteria: 1. Participants will be 45 - 70 years of age 2. MMSE \> 10 at screening visit. 3. Participants must be informed of the investigational nature of this study and provide written informed consent in accordance with institutional and federal guidelines prior to study-specific procedures. If the patient is unable to provide informed consent, the patient's legal representative may consent on behalf of the patient but the patient will be asked to confirm assent. 4. Participants must be willing and able to comply with scheduled visits and imaging procedures. 5. A brain MRI is required. If a brain MRI has been performed within 6 months of enrollment to this study and of adequate quality that scan may be used for the study analysis, subjects who do not have a brain MRI will undergo a brain MRI either as a part of this study 6. Participants must identify a study partner who is willing to accompany the patient to study visits Exclusion Criteria: 1. Females who are pregnant or breast feeding at the time of screening scan will not be eligible for this study, urine or serum pregnancy test will be performed in women of child-bearing potential at the time of screening 2. Inability to tolerate or contraindication to imaging procedures (PET/CT or MRI) in the opinion of an investigator or treating physician 3. QTc \> 450 msec on screening ECG. 4. Any medical or psychological conditions that, in the opinion of the investigator, would compromise the subject's safety or successful participation in the study (e.g. moderate to large stroke or history of moderate or severe traumatic brain injury (TBI)).