In Alzheimer's disease, what is dramatically decreased in several key brain areas?

• A. Cerebral blood flow
• B. Glucose metabolism
• C. Amyloid plaques
• D. Neurofibrillary tangles

Answer: (B)

Glucose metabolism in the brain is dramatically decreased in several key regions affected by Alzheimer's disease. Neuronal dysfunction and loss lead to reduced synaptic activity, which lowers the brain’s uptake and utilization of glucose. This hypometabolism is most pronounced in the temporoparietal cortex, posterior cingulate, and precuneus, and it correlates with the severity of cognitive impairment. Imaging with FDG-PET highlights this reduced glucose metabolism, making it a hallmark finding. In contrast, amyloid plaques and neurofibrillary tangles accumulate as part of the disease process rather than decrease, and while cerebral blood flow can decline with neurodegeneration, the most characteristic and consistent change observed is the drop in glucose metabolism.