Table 1

Mimics and chameleons of Alzheimer's disease (AD)

AD mimicsClues to diagnosis
Anxiety, worried well*Evidence for anxiety, neuropsychometric profile, normal MRI
Depression*Psychiatric features, neuropsychometric profile, normal MRI
Other neurodegenerative diseases*Non-AD-like MRI or hypometabolism on functional imaging; abnormal dopamine transporter scan
Vascular cognitive impairment*Significant vascular burden, or strategic infarcts on MRI
Transient epileptic amnesiaClinical seizures, epileptiform changes on EEG
Obstructive sleep apnoeaAbnormal sleep study
Autoimmune or paraneoplastic encephalitisIdentifiable antibody, abnormal MRI signal, neuropsychometric profile, evidence of neoplasia
Space-occupying lesionsBrain imaging findings
Metabolic diseaseBlood screen
Korsakoff's psychosisSignificant alcohol history; history of Wernicke's encephalopathy
AD chameleons
Young onset AD*Compatible neuropsychometry, MRI§
Posterior cortical atrophy*Compatible neuropsychometry, MRI, normal ophthalmology exam—visual fields often abnormal in an ‘unusual pattern’§
Rapidly progressive AD§
Familial ADCompatible family history, genetics
Logopenic aphasiaSpeech phenotype, neuropsychometric profile§
Progressive non-fluent aphasia§
Semantic dementia-like syndrome§
Frontal/dysexecutive AD§
  • *Common.

  • Uncommon but important.

  • Unusual/theoretical.

  • §For each of these syndromes, cerebrospinal fluid profile (raised total or p-tau, low Aβ1–42, elevated Aβ1–42/tau ratio) if available or, when clinically available, amyloid positron emission tomography imaging may suggest AD.