What are neurofibrillary tangles composed of?

Neurofibrillary tangles are primarily composed of hyperphosphorylated tau protein. Tau is a microtubule-associated protein that stabilizes microtubules in neurons. In certain neurodegenerative conditions, such as Alzheimer's disease, tau undergoes hyperphosphorylation, leading to the formation of aggregates within the neuronal cytoplasm. This aggregation disrupts the normal function of microtubules, contributing to cell dysfunction and death.

The presence of neurofibrillary tangles is a hallmark of Alzheimer's disease and is associated with cognitive decline. By identifying hyperphosphorylated tau as the primary component of these tangles, we can better understand the pathological processes underlying Alzheimer's and other tauopathies, which are conditions characterized by tau accumulation.

While other options reference proteins and aggregates involved in various neurological diseases—such as beta-amyloid plaques in Alzheimer's disease, alpha-synuclein in Parkinson's disease, and leucine-rich repeat kinase 2 related to familial Parkinson's disease—they do not specifically describe the composition of neurofibrillary tangles. Thus, the focus on hyperphosphorylated tau protein is essential for recognizing the pathology of neurofibrillary tangles in neurodegenerative disorders.