How do neuritic plaques and neurofibrillary tangles relate to Alzheimer disease?

Neuritic plaques and neurofibrillary tangles are hallmark tissue lesions found in the cerebral cortex of patients with Alzheimer disease and are used to diagnose the condition during autopsy.12

• Neuritic plaques: Also known as amyloid or senile plaques, these consist of deteriorating neuronal material surrounding a core of a sticky protein called amyloid beta. This protein is derived from amyloid precursor protein, a normal component of nerve cells.12
• Neurofibrillary tangles: These are twisted fibers of a protein called tau located within neurons. When incorrectly processed, these tau molecules clump together to form the tangles.12

While both structures are thought to interfere with normal cellular functioning, it remains unknown whether they are a primary cause or a consequence of the disease. Some research suggests that amyloid beta may function as a natural antibiotic in response to infection, leading to theories that plaque formation might be linked to an abnormal immune response in the brain.1