Are amyloid plaques and tau tangles a cause or a consequence of Alzheimer disease?

Whether amyloid plaques and tau tangles are a cause or a consequence of Alzheimer disease remains a subject of scientific uncertainty. While these features are hallmark indicators used to diagnose the condition during autopsy, it is not definitively known if they trigger the disease or are merely a byproduct of its progression.12

Neuritic plaques consist of amyloid beta deposits, while neurofibrillary tangles are composed of tau fibers. Both are thought to interfere with normal cellular function, and their presence is associated with the loss of neurons and neurotransmitter deficiencies. Some research suggests that amyloid-beta plaques may form as a natural response to infection, implying that in Alzheimer patients, this process might be excessive or abnormal. Although certain genetic mutations are linked to increased amyloid deposition, the precise causal relationship between these protein aggregates and the onset of the disease continues to be investigated.12