Imaging Tau in Alzheimer's Disease and Normal Aging

Phase 2

Terminated

Brief Summary: This study is being done to learn about tau tangles in Alzheimer's disease. A type of PET scan is used to measure the abnormal accumulation of protein called tau in the brain. These are thought to be involved in Alzheimer's disease. The investigators will also perform brain MRI and to tests to measure the participant's memory and thinking.

Detailed Description: This study is being done to determine the relationship between tau tangles and cognitive impairment in elderly subjects with different clinical and biomarker profiles of Alzheimer's disease (AD). Subjects will undergo screen that includes neuropsychological testing and brain MRI. This study uses a special type of scan called a PET scan to take pictures of the brain. During the PET scan, a special radioactive dye called 18F-THK-5351 is injected into the body. 18F-THK-5351 sticks to abnormal tangles made of the protein tau. Subjects will have the option to have lumbar puncture performed to measure CSF concentrations of biomarkers.

Recruitment & Eligibility

Inclusion Criteria

Age 50 and older.
Meet criteria for either a) amnestic mild cognitive impairment (single or mixed domain) or mild Alzheimer's disease, or b) have no cognitive impairment, based on history, exam, neuropsychological testing, and consensus diagnosis. MCI and mild AD patients must have Clinical Dementia Rating scale score of 0.5 or 1. Unimpaired subjects must have Clinical Dementia Rating scale score of 0.
Subjects unable to provide informed consent must have a surrogate decision maker.
Written and oral fluency in English or Spanish.
Able to participate in all scheduled evaluations and to complete all required tests and procedures.
In the opinion of the investigator, the subject must be considered likely to comply with the study protocol and to have a high probability of completing the study.

Exclusion Criteria

Past or present history of certain brain disorders other than MCI or AD.
Certain significant medical conditions, which make study procedures of the current study unsafe. Such serious medical conditions include uncontrolled epilepsy and multiple serious injuries.
Contraindication to MRI scanning.
Conditions precluding entry into the scanners (e.g. morbid obesity, claustrophobia, etc.).
History of kidney disease or presence of impaired kidney function based on laboratory tests at the screening visit.
History of liver disease or presence of impaired liver function based on laboratory tests at the screening visit.
Participation in the last year in a clinical trial for a disease-modifying drug for AD.
Inability to have a catheter in subject's vein for the injection of radioligand.
Inability to have blood drawn from subject's veins.

Arm && Interventions

Group	Intervention	Description
Cognitive impairment	Lumbar Puncture (optional)	Adults with Alzheimer's disease, preclinical Alzheimer's disease or impairment due to suspected non-Alzheimer's disease pathophysiology will receive 18F-THK- 5351 and/or lumbar puncture (optional).
Cognitive impairment	18F-THK-5351	Adults with Alzheimer's disease, preclinical Alzheimer's disease or impairment due to suspected non-Alzheimer's disease pathophysiology will receive 18F-THK- 5351 and/or lumbar puncture (optional).
No cognitive impairment	18F-THK-5351	Normal aging adults will receive 18F-THK- 5351 and/or lumbar puncture (optional).
No cognitive impairment	Lumbar Puncture (optional)	Normal aging adults will receive 18F-THK- 5351 and/or lumbar puncture (optional).

Primary Outcome Measures

Name	Time	Method
18F-THK-5351 Standardized Uptake Value Ratio	PET image data collected 50 min post-injection to 70 min post-injection of 18F-THK-5351	The standardize uptake value ratio is the concentration of radioactivity measured from the 18F-THK-5351 PET scan in the posterior cingulate gyrus, divided by that in the cerebellar gray matter (the reference region, which is expected to be devoid of tau pathology). This ratio is a relative measure of 18F-THK-5351 binding, and therefore of tau pathology, in brain tissue. PET image data was acquired from 50 min post-injection to 70 min post-injection of 18F-THK-5351.

Secondary Outcome Measures