The findings also could potentially be used to diagnose Alzheimers disease in living people instead of during an autopsy, says Amanda J. Haes, Ph.D., a co-author of the study. At present, Alzheimers can only be accurately diagnosed after death.
Haes, a National Research Council postdoctoral researcher at the Naval Research Laboratory in Washington, conducted this work while she was a graduate student at Northwestern under the direction of Richard Van Duyne. The findings were presented today at the 230th national meeting of the American Chemical Society, the worlds largest scientific society.
Haes, in cooperation with Van Duyne, Northwestern professor William Klein and research associate Lei Chang developed a method to detect small harmful proteins in cerebrospinal fluid using nanoscale optical biosensors. The proteins, known as ADDLs (amyloid ?-derived diffusible ligands) are so small that they cant be detected by conventional diagnostic tests. They are usually less than 5 nanometers wide and are found in extremely low concentrations.
Discovered by Klein in 1998, ADDLs accumulate in the brain tissue of individuals with Alzheimers disease at levels up to 70 times higher than found in people who dont have the disease. Many researchers now suspect that ADDLs cause some of the earliest symptoms of Alzheimers disease. ADDLs, they theorize, attack and disrupt synapses, the sites on nerve cells that are critical for memory formation and information processing. ADDLs tend to stick together, and some researchers suspect that as they