Brain PET Scans (IMAGE) University of California - Los Angeles Caption Brain PET scans from a healthy volunteer (left), a subject with mild cognitive impairment (middle) and a subject with Alzheimer's disease (right). Red and yellow areas show the new chemical marker FDDNP binding to abnormal brain proteins or "plaques and tangles." Credit UCLA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.