Alzheimer disease (AD) is a clinical-neuropathological diagnosis . Affected individuals have slowly progressive dementia (see Clinical Description), gross cerebral cortical atrophy by neuroimaging studies and microscopic A Beta amyloid neuritic plaques, intraneuronal neurofibrillary tangles, and amyloid angiopathy at postmortem examination. The numbers of plaques and tangles must exceed those found in non-demented age-matched controls and there are guidelines for these quantitative changes . The plaques should stain positively with A Beta amyloid antibodies and negative for prion antibodies.
clinical diagnosis of AD (prior to autopsy confirmation) is correct about
80-90% of the time . Incorrect clinical diagnosis of AD is usually the
result of one of the disorders noted under Diagnoses Excluded.