Which of the following is a key pathological feature of Alzheimer's disease?

The presence of amyloid plaques is a key pathological feature of Alzheimer's disease and plays a significant role in its progression. These plaques are formed by the accumulation of beta-amyloid peptides, which are fragments of a larger protein known as amyloid precursor protein (APP). In Alzheimer's, the process of breaking down APP becomes abnormal, leading to excessive production and deposition of beta-amyloid that clumps together, forming plaques in the brain.

Amyloid plaques disrupt cell communication, trigger inflammatory responses, and contribute to neuronal degeneration. This accumulation is one of the hallmarks used in diagnosing Alzheimer's disease and is associated with the cognitive decline observed in patients. The plaques typically aggregate in areas of the brain that are critical for memory and learning, which correlates with the symptoms experienced by individuals with Alzheimer’s.

In contrast to amyloid plaques, the other options do not accurately reflect pathological features directly associated with Alzheimer's disease. Inflammation of the spinal cord and thickening of blood vessels are not primary characteristics of the disease, while a decrease in gray matter density, while observable in Alzheimer's, does not represent a specific pathology like the formation of amyloid plaques. Thus, the presence of these plaques is a defining characteristic of Alzheimer's pathology and is essential for understanding the disease's