AD mimics | Clues 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 amnesia† | Clinical seizures, epileptiform changes on EEG |
Obstructive sleep apnoea† | Abnormal sleep study |
Autoimmune or paraneoplastic encephalitis‡ | Identifiable antibody, abnormal MRI signal, neuropsychometric profile, evidence of neoplasia |
Space-occupying lesions‡ | Brain imaging findings |
Metabolic disease‡ | Blood screen |
Infections‡ | Serology |
Korsakoff's psychosis‡ | Significant 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 AD† | Compatible family history, genetics |
Logopenic aphasia† | Speech 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.