The Pittsburgh Compound is a radioactive compound which was developed to successfully cross the blood-brain barrier. It is significant to Alzheimer's research because it attaches itself to beta amyloid plaques for a short period of time before it clears out of the brain. The half life of the compound is 20 minutes. This allows for the plaque tangles to be seen by the use of a PET scan. It took over 10 years of research to identify the compound and it has been available for use in research since at least 2004.
The compound allows for the tangles to be identified in living patients. This is significant because Alzheimer's was previously only fully diagnosed through a post-mortem exam. The hope was that the compound would aid not just in diagnostics, but also in researching other compounds which could be made small enough to cross the blood-brain barrier for the purpose of clearing out the tangles.
In the years since, that research has not yet resulted in a cure. However, another compound has been created. It is Florbetapir. Florbetapir is similar to the Pittsburgh Compound in function however, it is based off of a different chemical and has a radioactive half life of 110 minutes. It received FDA approval for use in diagnosing Alzheimer's in 2011.
Tests have continued on the two compounds to determine if they really were imaging the plaque tangles. The final confirmation required the brains of previously imaged patients to be physically examined in a post-mortem exam and the plaque tangles counted. Those count where then compared to the results of the scans done with the the Pittsburg Compound and a second set of scans done with Florbetapir.
A year ago, an article was published with the findings that both sets of scans were found to be consistent in their results with the results of the autopsies.