Caption: PET scan images show distribution of tau (top panel) and beta-amyloid (bottom panel) across a brain with early Alzheimer’s disease. Red indicates highest levels of protein binding, dark blue the lowest, yellows and oranges indicate moderate binding. Credit: Brier et al., Sci Transl Med
In people with Alzheimer’s disease, changes in the brain begin many years before the first sign of memory problems. Those changes include the gradual accumulation of beta-amyloid peptides and tau proteins, which form plaques and tangles that are considered hallmarks of the disease. While amyloid plaques have received much attention as an early indicator of disease, until very recently there hadn’t been any way during life to measure the buildup of tau protein in the brain. As a result, much less is known about the timing and distribution of tau tangles and its relationship to memory loss.
Now, in a study published in Science Translational Medicine, an NIH-supported research team has produced some of the first maps showing where tau proteins build up in the brains of people with early Alzheimer’s disease . The new findings suggest that while beta-amyloid remains a reliable early sign of Alzheimer’s disease, tau may be a more informative predictor of a person’s cognitive decline and potential response to treatment.
Caption: GluCEST imaging of the brain of a person with drug-resistant epilepsy, showing the hippocampi (highlighted) with signal for high glutamate (red). Credit: Reddy Lab, University of Pennsylvania
For many of the 65 million people around the world with epilepsy, modern medications are able to keep the seizures under control. When medications fail, as they do in about one-third of people with epilepsy, surgery to remove affected brain tissue without compromising function is a drastic step, but offers a potential cure. Unfortunately, not all drug-resistant patients are good candidates for such surgery for a simple reason: their brains appear normal on traditional MRI scans, making it impossible to locate precisely the source(s) of the seizures.
Now, in a small study published in Science Translational Medicine , NIH-funded researchers report progress towards helping such people. Using a new MRI method, called GluCEST, that detects concentrations of the nerve-signaling chemical glutamate in brain tissue , researchers successfully pinpointed seizure-causing areas of the brain in four of four volunteers with drug-resistant epilepsy and normal traditional MRI scans. While the findings are preliminary and must be confirmed by larger studies, researchers are hopeful that GluCEST, which takes about 30 minutes, may open the door to new ways of treating this type of epilepsy.