In 1906, Alois Alzheimer, a psychiatrist and neuroanatomist, reported “a peculiar severe disease process of the cerebral cortex” to a gathering of psychiatrists in Tübingen, Germany. The case was a 50-year-old woman who suffered from memory loss, delusions, hallucinations, aggression and confusion – all of which worsened until her untimely death five years later.
In the autopsy, Alzheimer noticed distinctive plaques on her brain. These plaques – clumps of amyloid-beta protein – are still considered to be the cause of Alzheimer’s disease.
However, this theory has two major problems. First, it does not explain why many subjects (even old people) have plaques in their brains in the absence of any neurological symptoms, such as memory loss. Second, clinical trials for drugs that reduce these plaques have been unsuccessful – with one recent exception, but more of that later.
