Which stain is commonly used to aid in the diagnosis of Alzheimer's disease?

• A. Bielschowsky
• B. Cajal
• C. PTAH
• D. Bodian

Answer: (A)

Visualizing the hallmark lesions of Alzheimer's disease is the central idea here. Neurofibrillary tangles and neuritic plaques are best seen with silver impregnation methods, which differentially stain these structures to stand out against the surrounding tissue. Bielschowsky stain is favored because it provides a clear, high-contrast visualization of both tangles and plaques, making the characteristic patterns easy to identify and assess across brain regions. This stain has long been a standard tool in diagnostic neuropathology for evaluating Alzheimer-type changes, and its ability to highlight these specific pathology is why it’s commonly used.

Other stains listed can reveal neural elements or tangles, but they’re not as specifically informative for Alzheimer lesions. The Cajal method and Bodian stain are valuable silver stains for certain neural components, yet they don’t offer the same combination of clarity and diagnostic usefulness for both neurofibrillary tangles and neuritic plaques as Bielschowsky. PTAH is more oriented toward muscle fibers and general neural elements and doesn’t provide the same targeted contrast for Alzheimer's hallmarks. In practice, Bielschowsky’s ability to distinctly show the key AD features makes it the best choice among these options.