Use MRI findings in AD, PET/SPECT findings in AD, and the pathological hallmarks of AD to frame the working diagnosis and next step; treat it as a safety constraint before prescribing or reassuring. Make PET/SPECT findings in AD the checkpoint that determines whether you escalate testing, narrow the differential, or change treatment.

This volume loss is so distinct that it can often be picked up early on, even during the mild cognitive impairment stage; Functional imaging usually reveals a very specific pattern of low activity; Structural shrinkage, specifically medial temporal lobe and hippocampal atrophy; Under the microscope, you'll see a collection of classic features: widespread neuronal loss, neurofibrillary tangles, extracellular amyloid plaques, granulovacuolar degeneration, Hirano bodies, and signs of cerebral amyloid angiopathy; Abnormal structures made up of paired helical filaments of hyperphosphorylated tau protein