Final answer:
Alzheimer's disease can be diagnosed pathologically through an autopsy, which is the only definitive method to identify amyloid plaques and neurofibrillary tangles characteristic of the disease.
Step-by-step explanation:
Alzheimer's disease can be definitively diagnosed pathologically through a Option 3: Autopsy. An autopsy allows direct examination of the brain tissue, revealing the presence of hallmark characteristics of Alzheimer's, such as amyloid plaques and neurofibrillary tangles, which are associated with the disease. While research is ongoing to find early detection methods, such as blood tests for biomarkers or brain scans using radiolabeled chemicals like Pittsburgh Compound B (PiB), these currently are not definitive for diagnosis and are more about detecting risk or early signs of the disease.
In Alzheimer's disease, the abnormal changes including amyloid plaques, neurofibrillary tangles, and the loss of neurons, especially in the hippocampus, result in cognitive decline, and this damage worsens over time as the disease progresses through mild, moderate, and severe stages. Clinicians categorize the progression of Alzheimer's, but definitive diagnosis usually occurs post-mortem, when these changes can be clearly identified.
Figure 11.1.2 indicates a comparison between a healthy brain and an Alzheimer's-affected brain, showing a marked difference in size, highlighting how AD is a progressive disease leading to a shrinking of brain volume over time. Although there is no cure, treatments such as cholinesterase inhibitors can slow the progression of the disease.