What Are Neurofibrillary Tangles?

Neurofibrillary tangles are pathological changes in the cerebral cortex cells of patients with Alzheimer's disease. It is also seen in other neurodegenerative patients. Traditionally confirmed by histological silver staining. Under light microscopy, the aggregates of neurofibrils stained in neurons are in different shapes and can be oriented. It appears as a flame in the neocortex, hanging from the bottom of the neuron and extending to the apical dendrites; it can also be unoriented and spherical. Under the electron microscope, the patient's NFT consisted of a straight nerve wire and a double-stranded spiral nerve wire. Many studies have shown that NFT is related to abnormal cytoskeleton composition. Immunohistochemical staining confirmed the presence of phosphorylated and non-phosphorylated neural filaments and microtubule-associated protein MAP. ^[1]

Neurofibrillary tangles

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Neurofibrillary tangles are pathological changes in the cerebral cortex cells of patients with Alzheimer's disease. It is also seen in other neurodegenerative patients. Traditionally confirmed by histological silver staining. Under light microscopy, the aggregates of neurofibrils stained in neurons are in different shapes and can be oriented. It appears as a flame in the neocortex, hanging from the bottom of the neuron and extending to the apical dendrites; it can also be unoriented and spherical. Under the electron microscope, the patient's NFT consisted of a straight nerve wire and a double-stranded spiral nerve wire. Many studies have shown that NFT is related to abnormal cytoskeleton composition. Immunohistochemical staining confirmed the presence of phosphorylated and non-phosphorylated neural filaments and microtubule-associated protein MAP. ^[1]

(1) Neurofibrils are thickened and twisted to form tangles, which are often blurred in HE staining, and silver staining is the most clear. It is confirmed by double-spiral filaments under electron microscope, which is more common in larger neurons, especially the hippocampus , Amygdala, medial temporal lobe, and pyramidal cells of the frontal cortex are most common. This change is a sign that neurons tend to die.

(2) Neuron fiber tangles are the second major pathological change that causes senile dementia. For senile dementia, neurofibrillary tangles are not specific changes, they are also found in normal elderly and other neurological degenerations. However, it is different from neuron fiber tangles in its ultrastructure and immunohistochemical characteristics. Neuron fiber tangles are the main cause of neuron fiber degradation and can be used as a sign of premature aging of the brain. However, patients with senile dementia have more neuron fiber tangles in the brain than normal elderly people, and they are distributed throughout the brain. Neuron fiber tangles have different morphologies in different neurons.

Neuronal fiber tangles increase with the development of senile dementia and are related to the degree of clinical dementia. The main component of neuron fiber tangles is paired helical filaments. The paired spiral filaments form a parallel bundle, and the filaments are connected to each other to form a mixed microfilament. The paired spiral filaments exhibit unique insolubility and resistance to proteolysis. The subunits of the paired helix are mainly hyperphosphorylated Tau protein.

Using CT to measure hippocampal volume in patients with dementia found that hippocampal atrophy was found in 87% to 95% of individuals. The main manifestation is the enlargement of the choroidal fissure of the lateral ventricle on the axial view. Studies on non-demented normal elderly have shown that the probability of hippocampal atrophy increases with age, but is far lower than that of patients with senile dementia. The follow-up survey showed that the normal elderly with hippocampal atrophy had significantly higher rates of potential risk of senile dementia than those with normal hippocampal volume.