2026 Edition,Amyloid β protein (Aβ) is the main component of neuritic plaques

Amyloid plaques made of beta peptide are a hallmark of Alzheimer's disease, representing abnormal clumps of protein fragments that accumulate outside of nerve cells in the brain. These plaques, primarily composed of amyloid beta peptide (Aβ), are a critical area of research in understanding and potentially treating neurodegenerative disorders like Alzheimer's.

The amyloid beta (Aβ) peptide originates from a larger transmembrane protein known as the amyloid precursor protein (APP). APP is a protein composed of 771 amino acids. Through a process called proteolytic processing, involving enzymes like β-secretase (BACE1) and γ-secretase, APP is cleaved to produce amyloid beta peptides. These peptides are typically fragments made of 36-43 amino acids. Among these, the amyloid beta 42 (Aβ42) variant is particularly implicated in Alzheimer's pathology, as it is more prone to aggregation. While smaller amounts of Aβ peptides are produced throughout life and may have normal physiological roles, their excessive production or impaired clearance can lead to their accumulation.

The aggregation of these amyloid beta peptides leads to the formation of amyloid plaques. These plaques are characterized by their β-sheet-rich assemblies, which contribute to their stable, insoluble structure. They are considered extracellular deposits of amyloid beta (Aβ) protein and are found predominantly in the grey matter of the brain. The presence of these amyloid plaques is considered one of the two lesions in the brain that define the neuropathological diagnosis of Alzheimer's disease, the other being neurofibrillary tangles made of tau protein.

The precise mechanism by which amyloid plaques contribute to Alzheimer's disease pathogenesis is still an active area of investigation. However, it is widely believed that the accumulation of amyloid beta (Aβ) peptide is a critical initiator that triggers the progression of Alzheimer's Disease (AD). These plaques can disrupt normal neuronal function and communication, potentially leading to synaptic dysfunction and neuronal death. Research suggests that beta amyloid may begin destroying synapses even before it clumps into visible plaques.

While amyloid plaques are a central feature, it's important to note that senile plaques can vary in their protein composition, not only in the types of Aβ peptides but also in the presence of other proteins. Understanding the intricacies of amyloid beta peptide production, aggregation, and deposition is crucial for developing effective therapeutic strategies. Researchers are exploring various avenues, including ways to reduce the production of beta-amyloid, enhance its clearance, and prevent its aggregation, to combat the devastating effects of Alzheimer's disease. The study of amyloid beta and its role in the development of Alzheimer's disease continues to be a priority in neuroscience, aiming to shed light on the complex mechanisms underlying this condition.