Biomarkers currently used in diagnostic criteria
| Criteria | Comments |
|---|---|
| AD | |
| Biomarkers of amyloid pathology: Low CSF Aβ1-42 on CSF examination Positive amyloid PET scan | Either evidence of low CSF Aβ1-42 or positive amyloid PET scan required for diagnosis of amyloid brain deposition15 |
| Biomarkers of neuronal injury: Elevated CSF tau and phospho-tau; Hypometabolism on FDG-PET; Disproportionate atrophy of medial, basal and lateral temporal lobe, and medial parietal cortex on structural MRI | Either elevated CSF tau, FDG-PET changes or structural MRI changes required for a diagnosis of neuronal injury15 |
| McKhann criteria15 require evidence of amyloid pathology and neuronal injury to support a diagnosis of highly probable AD (biomarker evidence only recommended in individuals who do not meet the core clinical criteria for probable AD dementia).Dubois criteria (IWG2)26 require specific clinical features of AD (typical or atypical) plus evidence of in vivo AD pathology. Evidence of in vivo AD pathology: low CSF Aβ1-42 together with increased total-tau or phospho-tau or positive amyloid PET or proven mutation in PSEN1, PSEN2, or APP or other proven genes (including Down’s syndrome trisomy 21). | |
| Frontotemporal dementia | |
| bvFTD | |
| Frontal and/or anterior temporal lobe atrophy on MRI or CT | Either structural or PET imaging changes required for a diagnosis of probable bvFTD100 |
| Frontal and/or anterior temporal lobe hypoperfusion or hypometabolism on PET or SPECT | |
| Progressive non-fluent aphasia | |
| Predominant left posterior frontoinsular atrophy on MRI | Either structural or PET imaging changes required for an imaging supported diagnosis58 |
| Predominant left posterior frontoinsular hypoperfusion or hypometabolism on SPECT or PET | |
| Semantic dementia | |
| Predominant anterior temporal lobe atrophy | Either structural or PET imaging changes required for an imaging supported diagnosis58 |
| Predominant anterior temporal hypoperfusion or hypometabolism on SPECT or PET | |
| Dementia with Lewy bodies | |
| Relative preservation of medial temporal lobe structures on CT/MRI | Supportive feature (commonly present but not proven to have diagnostic specificity) |
| Generalised low uptake on SPECT/PET perfusion scan with reduced occipital activity | Supportive feature (commonly present but not proven to have diagnostic specificity) |
| Abnormal (low uptake) MIBG myocardial scintigraphy | Supportive feature (commonly present but not proven to have diagnostic specificity) |
| Abnormal uptake on PET/SPECT (eg, 123 I-FP CIT- DaTSCAN) | Supportive feature (used to differentiate DLB from AD and some forms of FTD) |
AD, Alzheimer's disease; APP, amyloid precursor protein; bvFDT, behavioural variant frontotemporal dementia; CSF, cerebrospinal fluid; FDG, 18-F-flourodeoxyglucose; MIBG, metaiodobenzylguanidine ; p-tau, tau phosphorylated at 181; PET, positron emission tomography; SPECT, single photon emission tomography; t-tau, total tau.