Obligatory medical device diagnostics.
- Computed tomography/magnetic resonance imaging of the skull (cranial CT or.cCT/cranial MRI or cMRI) for basic diagnosis; recommendation grade A [S3 guideline] – to exclude brain-organic changes and to assess the degree of atrophy; this primarily reveals the following signs
- Volume reduction in the temporal lobe (amygdala, hippocampus).
Note: The specificity of structural MRI is too low to base the differentiation of AD or frontotemporal dementia from other neurodegenerative dementias on this alone. In addition to imaging (extent and location of vascular lesions), history, clinical findings, and neuropsychological profile should be used to determine vascular dementia. Grade of recommendation B [S3 guideline]Note: White matter hyperintensities are associated with poor cognitive performance-but only in those younger than 80 years.
Optional medical device diagnostics – depending on the results of the history, physical examination, laboratory diagnostics and obligatory medical device diagnostics – for differential diagnostic clarification.
- Encephalogram (EEG; recording of the electrical activity of the brain) – for suspected seizure disorders, delirium, Creutfeldt-Jacob disease.
- Doppler sonography (ultrasound examination that can dynamically display fluid flow (especially blood flow)) of the carotids (carotid arteries) – indicated in additional vascular (vascular) problems.
- PET or SPECT to detect a dopaminergic deficit may be used in clinically unclear cases for the differential diagnosis of Lewy body dementia vs non-Lewy body dementia [S3 line]:
- Single-photon emission tomography (SPECT) suitable for diagnosis of AD as well as lobar dementias; caveat: availability, lack of studies.
- Positron emission tomography (PET) measured by fluorodeoxyglucose (FDG)-PET – in vivo detection of amyloid beta plaques possible in patients with AD [hypometabolism in the brain measured by fluorodeoxyglucose]Cave! A positive amyloid scan does not equate to a diagnosis of AD. A positive amyloid detection by PET must be interpreted in the overall context especially considering the clinical findings and other biomarker information [S3-guideline]. Note: A positive amyloid PET finding may be suggestive of underlying Alzheimer’s disease, whereas a negative amyloid PET finding may be suggestive against underlying Alzheimer’s disease [S3-guideline].
- Sleep apnea screening – see below Sleep apneaNote: Disturbed sleep-wake rhythm is associated with increased amyloid deposition (Alzheimer’s dementia).
