What is the Difference Between Amyloid Plaques and Neurofibrillary Tangles

The key difference between amyloid plaques and neurofibrillary tangles is that amyloid plaques are the gradual accumulations of beta-amyloid protein fragments between neurons in Alzheimer’s disease, while neurofibrillary tangles are the accumulations of tau proteins within healthy neurons in Alzheimer’s disease.

Amyloid plaques and neurofibrillary tangles are two hallmark characteristics of the brain tissue associated with Alzheimer’s disease. Both these characteristics are extremely important in diagnosing Alzheimer’s disease through brain imaging. These unique structures are thought to interfere with nervous messages within the brain. However, the exact role of these unique structures is not known yet. Moreover, it remains unclear if they cause Alzheimer’s disease or if they are a byproduct.

CONTENTS

1. Overview and Key Difference
2. What are Amyloid Plaques 
3. What are Neurofibrillary Tangles
4. Similarities – Amyloid Plaques and Neurofibrillary Tangles
5. Amyloid Plaques vs Neurofibrillary Tangles in Tabular Form
6. Summary – Amyloid Plaques vs Neurofibrillary Tangles

What are Amyloid Plaques?

Amyloid plaques are the gradual build-up or accumulation of beta-amyloid protein fragments (protein peptides) between neurons in Alzheimer’s disease. These plaques consist of dense, insoluble clumps in the spaces between nerve cells in the brain. The beta-amyloid protein fragments appear to have toxic effects on brain cell function.

During the disease progression, some people may develop amyloid plaques in the central nervous system as they age. Moreover, some parts of the brain are particularly prone to amyloid plaque development. Hippocampus is one such part. Normally, the hippocampus controls the processing of short-term to long-term memories. Therefore, damage to the hippocampus is associated with symptoms of Alzheimer’s disease. Furthermore, the role of amyloid plaques in the pathogenesis of Alzheimer’s disease is still not known. However, they are more prevalent in people who are suffering from Alzheimer’s disease. Additionally, few recent research studies found some evidence to support this as they identified some genetic mutations that lead to the increase in beta-amyloid accumulation responsible for causing some forms of Alzheimer’s disease.

What are Neurofibrillary Tangles?

Neurofibrillary tangles are the accumulation of tau protein within healthy neurons in Alzheimer’s disease. Neurofibrillary tangles are a knot of the brain cells and are a primary biomarker of Alzheimer’s disease. Neurofibrillary tangles are also found in other diseases or tauopathies, as well. Generally, in healthy individuals’ nervous systems, microtubules provide support to the neurons and help in the transportation of nutrients and vesicles. The tau protein threads with some phosphate molecules bind to these microtubules to stabilize them.

People who are suffering from Alzheimer’s disease have a large number of phosphate molecules bound to tau protein than in normal conditions (hyperphosphorylation). This causes the formation of paired helical filaments, which can then become tangled inside the neuron cell. Moreover, this formation also reduces the stability of microtubule support to neurons. Ultimately, all these processes collapse the internal neural network that inhibits neural communication.

What are the Similarities Between Amyloid Plaques and Neurofibrillary Tangles?

• Amyloid plaques and neurofibrillary tangles are two hallmark characteristics of the brain tissue associated with Alzheimer’s disease.
• Both these characteristics are extremely important in diagnosing Alzheimer’s disease through brain imaging.
• These unique structures are thought to interfere with nervous messages within the brain.
• However, the exact role of these unique structures in Alzheimer’s disease is not known yet, whether they cause Alzheimer’s disease or if they are a byproduct.

What is the Difference Between Amyloid Plaques and Neurofibrillary Tangles?

Amyloid plaques are the gradual accumulations of beta-amyloid protein fragments between neurons in Alzheimer’s disease. At the same time, neurofibrillary tangles are the accumulations of tau protein within healthy neurons in Alzheimer’s disease. Thus, this is the key difference between amyloid plaques and neurofibrillary tangles. Furthermore, amyloid plagues are clusters in the spaces between nerve cells, while neurofibrillary tangles are knots of the brain cells.

The below infographic presents the differences between amyloid plaques and neurofibrillary tangles in tabular form for side-by-side comparison.

Summary – Amyloid Plaques vs Neurofibrillary Tangles

Amyloid plaques and neurofibrillary tangles are two peculiar characteristics of the brain tissue associated with Alzheimer’s disease. Both are extremely important in diagnosing Alzheimer’s disease. Amyloid plaques are the gradual accumulation of beta-amyloid protein fragments between neurons in Alzheimer’s disease. In contrast, neurofibrillary tangles are the accumulation of tau protein within healthy neurons in Alzheimer’s disease. So, this summarizes the difference between amyloid plaques and neurofibrillary tangles.

Reference:

1. Robertson, Sally. “What Are Amyloid Plaques?” News, 23 Aug. 2018.
2. Metaxas, Athanasios, and Stefan J Kempf. “Neurofibrillary Tangles in Alzheimer’s Disease: Elucidation of the Molecular Mechanism by Immunohistochemistry and Tau Protein Phospho-Proteomics.” Neural Regeneration Research, U.S. National Library of Medicine, Oct. 2016.

Image Courtesy:

1. “Neurofibrillary tangles in the Hippocampus of an old person with Alzheimer-related pathology, HE 2” By Patho – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Beta-Amyloid Plaques and Tau in the Brain” By NIH Image Gallery (Public Domain) via Flickr