A 85-year-old male patient has been suffering from progressive memory loss over the last two years. She also needs help with her daily activities. MRI revealed diffuse coical and hippocampal atrophy in this patient. HPE in such conditions demonstrates the following findings. Which of the following drug used in the treatment of the above condition does not act by increasing acetyl choline levels in nucleus basalis of meyne?

The patient is suffering from Alzheimer's disease. HPE shows: A. Neurofibrillary tangles and neuropil threads (Gallya's silver staining) B. Fibrillar nature of tangles (arrows) neuritic plaques (arrowheads), whose major component - Ab (inset - immunohistochemistry for Ab). Treasure 8 (pathology) Drugs used in the management of Alzheimer's disease: Central acting choline esterase inhibitors: Tacrine: hepatotoxic Rivastigmine Gallantamine Donepezil NMDA antagonist: Memantine Impoant points about Alzheimer's disease: Predominant clinical symptoms: Slow, progressive memory loss with loss of executive function Macroscopic brain appearance: Generalized brain atrophy Microscopic brain appearance: Neurofibrillary tangles, senile plaques and cerebral amyloid angiopathy Biochemical abnormalities: Decreased acetylcholine levels in the hippocampus and nucleus basalis of meyne.