Episode 20: Alzheimer’s is a complex disease. Although we have yet to discover a cure, we have discovered that there is not one single cause of Alzheimer's disease. For a long time, researchers thought the disease was caused by the abnormal build-up of amyloid proteins around brain cells. Now, they believe that another protein, tau, is equally responsible by forming tangles within brain cells. And there may be others as well. If this sounds confusing, join us as we speak to Tanya Lewis, associate editor for health and medicine at Scientific American, who explains - in simple terms - all of this and much, much more.