New clue for diagnosing Alzheimer's Disease
Scientists are still in the dark about what exactly causes Alzheimer’s disease.
This is despite the fact that many billions of dollars have been spent on research by the National Institutes of Health (NIH) and pharmaceutical companies worldwide.
Alzheimer’s is also very difficult to diagnose. Recently, PET scan procedures have become better at analysing who may have the disease, but an autopsy is still the only way to confirm a diagnosis.
PET scans are used to look for the sticky beta-amyloid protein plaques that surround brain cells as it is thought that the more of these plaques you have, the more likely it is that you are developing Alzheimer’s. Therefore, individuals with an exceptional amount of amyloid plaques are usually diagnosed as having early-stage Alzheimer’s disease. However, this theory is rather flawed as autopsy evidence shows that nearly a third of all people who do not display any signs of dementia have a multitude of amyloid plaques in their brains when they die.
A study featured recently in the journal ‘Science Translational Medicine’ deals with this issue by concentrating on a different plaque, also associated with Alzheimer’s, called tau protein.
Recent advances in scanning techniques have given researchers the opportunity to bind an agent to tau proteins in the brain to see how many of them are present.
Scientists at Washington University in St. Louis studied ten patients diagnosed with early-stage Alzheimer’s and thirty-six adults who were free of the disease. Binding agents were used to see both amyloid plaques and tau plaques. It was discovered that the more tau plaques found in the temporal lobe of the brain, the more likely it was that the person would not perform well on memory tests.
One theory that has arisen is that the brain may be able to deal with a certain level of amyloid plaque progression, but when tau plaques start forming in abundance they can result in late-stage Alzheimer’s disease. This means that PET scans for tau could be useful in diagnosing Alzheimer’s.