**Question:** An elderly patient dies with chronic dementia. At autopsy, the brain showed diffuse coical atrophy with relative sparing of primary motor and sensory areas. Which of the following would most likely be a prominent feature on microscopic examination of her brain tissue?

A. Neurofibrillary tangles
B. Amyloid plaques
C. Neuronal loss
D. Vascular disease

**Core Concept:** In neuropathological examination of brains with dementia, we look for specific pathological changes. In Alzheimer's disease, the most prominent feature is neurofibrillary tangles (aggregates of hyperphosphorylated tau protein) and amyloid plaques (deposits of amyloid beta protein). These changes are associated with neuronal loss, which is a more general term encompassing neuronal atrophy and cell death. Vascular disease is also a potential cause of dementia, but it is less specific to dementia due to Alzheimer's disease.

**Why the Correct Answer is Right:** In Alzheimer's disease, the patient typically presents with progressive memory loss and cognitive decline, often accompanied by behavioral and personality changes. Microscopic examination of the brain reveals neurofibrillary tangles and amyloid plaques, which are characteristic of Alzheimer's disease. These changes contribute to neuronal loss, which is a more general term describing neuronal atrophy and cell death.

**Why Each Wrong Option is Incorrect:**

**A. Neuronal loss:** Although neuronal loss is present in Alzheimer's disease, it is not specific to Alzheimer's. Other conditions like vascular disease, encephalitis, and trauma can also cause neuronal loss.

**B. Amyloid plaques:** Although amyloid plaques are present in Alzheimer's disease, they are not exclusive to the condition. They can also be found in other neurodegenerative disorders like Lewy body dementia and frontotemporal dementia.

**C. Vascular disease:** Vascular disease can lead to cognitive impairment and dementia, but it is not specific to Alzheimer's disease. Vascular disease can coexist with Alzheimer's disease, but it is not the sole pathological feature of Alzheimer's.

**D. Vascular disease:** Vascular disease is a common comorbidity in Alzheimer's disease, but it is not the primary cause of Alzheimer's. Alzheimer's disease is a neurodegenerative disorder characterized by the accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles, leading to neuronal dysfunction and death.

**Clinical Pearl:** Alzheimer's disease is a common cause of dementia in geriatric patients. Recognizing the specific pathological features can help in the differential diagnosis when faced with a patient presenting with cognitive decline.