Alzheimer’s disease is usually diagnosed based on the person’s medical history, history from relatives, and behavioural observations. The presence of characteristic neurological and neuropsychological features and the absence of alternative conditions is supportive.[104][105] Advanced medical imaging with computed tomography (CT) or magnetic resonance imaging (MRI), and with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) can be used to help exclude other cerebral pathology or subtypes of dementia.[106] Moreover, it may predict conversion from prodromal stages (mild cognitive impairment) to Alzheimer’s disease.[107]
Assessment of intellectual functioning including memory testing can further characterise the state of the disease.[19] Medical organisations have created diagnostic criteria to ease and standardise the diagnostic process for practising physicians. The diagnosis can be confirmed with very high accuracy post-mortem when brain material is available and can be examined histologically.[108]
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