How did plaques and tangles play a role in the history of Alzheimer's?
Plaques and tangles were first described by a Bavarian psychiatrist by the name of Alois Alzheimer. That's how this illness derived its name, and, by the way, it was someone else that dubbed it Alzheimer's disease. So, Alois wasn't necessarily an egotist who named the illness after himself. He was the first individual that described this condition literally 100 years ago. So, back in 1907, a gentleman basically came in seeking Alois' help and basically stated that his wife, a woman by the name of Auguste D, who had started out with some memory problems, and again, this was a woman who was in her early fifties, had also developed some very strange and unusual symptoms. She had become psychotic and was having a lot of behavioural problems. Upon death, what Alois decided to do was to scoop out some brain tissue and take a look at it under a microscope. He found what are still considered the pathognomonic, or the telltale signs associated with the illness. The plaques, which he called senile plaques, are basically extra-cellular Beta-amyloid plaques and tangled neurons. In other words, this is a situation in which hyperphosphorylation of the tau protein with thin cells creates a problem, whereby the cytoskeleton of the neuron or the brain cell, all of a sudden, causes a collapse within itself. So, again plaques and tangles are the telltale signs that we need to verify that, in fact, this individual suffered from Alzheimer's disease. The reason that they are important is that this is the only way to make a 100% accurate diagnosis of the illness. One thing that is important, though, is that just based on the clinical acumen, or in other words, the notion that we have made sure that all other causes have been ruled out, the doctor can make a diagnostic certainty of this illness with a degree of about, maybe 90-95% accuracy.
