Psychology MCAT Practice Exam 2025 - Free Practice Questions and Study Guide for Aspiring Psychologists.

Alzheimer's disease is characterized by the presence of amyloid plaques and neurofibrillary tangles, which are key brain abnormalities associated with the condition. Amyloid plaques are deposits of beta-amyloid peptides that accumulate outside neurons, disrupting cell communication and triggering inflammatory responses. Neurofibrillary tangles consist of hyperphosphorylated tau protein that aggregates inside neurons, leading to their dysfunction and eventual cell death. The presence of these pathological features is crucial for the diagnosis of Alzheimer's and is linked to cognitive decline observed in individuals with the disease.

In contrast, the other options do not accurately reflect the core pathophysiological features of Alzheimer's disease. Excessive dopamine levels are more characteristic of psychiatric conditions such as schizophrenia rather than neurodegenerative diseases like Alzheimer's. Increased neural plasticity refers to the brain's ability to adapt and reorganize, which tends to decline in Alzheimer's as cognitive function deteriorates. Lastly, massive neuronal regeneration is not typical of Alzheimer's; instead, the disease is associated with neurodegeneration and loss of neuronal connections. Thus, the identification of amyloid plaques and neurofibrillary tangles provides critical insights into the mechanisms underlying Alzheimer's disease.