What is a hallmark of Alzheimer's disease found in the brain?

Senile plaques are a key hallmark of Alzheimer's disease and serve as a prominent pathological feature observed in the brains of affected individuals. These plaques consist primarily of beta-amyloid peptides that accumulate extracellularly, forming dense deposits that disrupt neuronal communication and may contribute to neurodegeneration. The presence of these plaques can be detected through histological examination, often using specific staining techniques that highlight the amyloid proteins.

In the context of Alzheimer's disease, the accumulation of senile plaques is associated with a range of clinical symptoms, including memory loss, cognitive decline, and behavioral changes. The degree of plaque formation correlates with the severity of the disease, making it a crucial element in both diagnosis and research targeting therapeutic interventions.

Meanwhile, the other options presented do not specifically characterize Alzheimer's disease in the same defining way. Microglial nodules can be a response to various types of brain injury and inflammation but are not exclusive to Alzheimer's. Rosenthal fibers, which are typically associated with conditions like Alexander disease or certain tumors, do not play a role in Alzheimer's pathology. Astrogliosis refers to the proliferation of astrocytes in response to injury or disease, which may occur in various neurological conditions, but it is not a defining feature of Alzheimer's disease itself. Thus,