What are the pathologic hallmarks of Alzheimer's disease?

What are the pathologic hallmarks of Alzheimer's disease?

• A. Lewy bodies
• B. Amyloid plaques & Neurofibrillary tangles
• C. Loss of myelin
• D. Gliosis

Answer: (B)

Amyloid plaques and neurofibrillary tangles are the defining pathologic features of Alzheimer's disease. The plaques are extracellular deposits of beta-amyloid protein that accumulate in the cortex, especially areas important for memory like the hippocampus, leading to synaptic loss and neuron death. The tangles are intracellular twisted fibers composed of hyperphosphorylated tau that disrupt microtubule stability and axonal transport, further impairing neuronal function and causing cell death. Together, the presence and spread of these two lesions correlate with the severity of cognitive decline. Lewy bodies are classic for Lewy body dementia and Parkinson disease, not the primary hallmark of Alzheimer disease. Loss of myelin points to demyelinating conditions, such as multiple sclerosis, rather than Alzheimer pathology. Gliosis is a nonspecific reactive change seen after CNS injury or degeneration and is not unique to Alzheimer disease.

Amyloid plaques and neurofibrillary tangles are the defining pathologic features of Alzheimer's disease. The plaques are extracellular deposits of beta-amyloid protein that accumulate in the cortex, especially areas important for memory like the hippocampus, leading to synaptic loss and neuron death. The tangles are intracellular twisted fibers composed of hyperphosphorylated tau that disrupt microtubule stability and axonal transport, further impairing neuronal function and causing cell death. Together, the presence and spread of these two lesions correlate with the severity of cognitive decline.

Lewy bodies are classic for Lewy body dementia and Parkinson disease, not the primary hallmark of Alzheimer disease. Loss of myelin points to demyelinating conditions, such as multiple sclerosis, rather than Alzheimer pathology. Gliosis is a nonspecific reactive change seen after CNS injury or degeneration and is not unique to Alzheimer disease.