Pittsburgh Compound B: An emerging technique for the diagnosis of Alzheimer's disease

Happy New Year! It's good to be back with you after a one-month hiatus. The first post of 2009 is by a guest blogger named Sarah Scrafford, who agreed to write an update on the status of Pittsburgh Compound B in the diagnosis of Alzheimer's disease. A graduate of Indiana Bloomington with a degree in English literature, Sarah is pursuing a career in online journalism. Here's Sarah's report:

According to Wikipedia, Pittsburg Compound B or PiB is “a fluorescent derivative of Thioflavin T, which can be used in positron emission tomography (PET) scans to image beta-amyloid plaques in neuronal tissue”. Simply put, it is a dye-like imaging agent that’s used in PET scans to determine the amount of beta-amyloid plaques in tissues in the brain. (The image depicts an Alzheimer brain on the right, which lights up with PiB, compared to a normal control brain on the left.) PiB was invented by Professors William E. Klunk (departments of psychiatry and neurology) and Chester A. Mathis (department of radiology) at the University of Pittsburgh School of Medicine.
PiB helps reveal the possibility of Alzheimer’s disease (AD) by binding to some forms of amyloid protein plaques that are believed to destroy brain cells and are a reason for people to develop the disease. Amyloid proteins hasten memory loss and lead to a degeneration of brain cells. The creation of PiB was a major breakthrough in the diagnosis of AD. Before PiB was invented, the only way doctors could prove that people were affected by AD was by autopsy – an answer that comes too late for an individual seeking treatment.
A new study conducted by the same team that invented PiB has paved the way to possibly detecting AD even before symptoms appear. The study, which is the largest of its kind, is led by Howard J. Aizenstein, associate professor of psychiatry and bioengineering at the University of Pittsburg, and includes the team of Klunk, Mathis, Robert D. Nebes, and Judith Saxton. The researchers found that PiB could be used to detect amyloid deposits before patients show signs of Alzheimer’s disease.
The study included 43 people between the ages of 65 and 88, all of whom performed well in cognitive tests, and 9 of whose PET scans showed the presence of amyloid deposits. PiB positivity in asymptomatic patients could be a sign that amyloid deposits are present in the brain long before the onset of symptoms, according to the researchers. But, warn the researchers, the study does not prove definitely that the presence of these deposits is a sure sign that clinical AD will develop. They are not revealing the results of the tests to the participants so as not to cause undue concern among those with a positive test, since the significance of a positive test in an asymptomatic individual is unknown. Instead, researchers will monitor the subjects of the study throughout their lives to study the predictive value of PiB scans.

This article is contributed by Sarah Scrafford.