The Clinical Use of Alzheimer’s Biomarkers in Patients With Mild Cognitive Impairment: A European Alzheimer’s Disease Consortium Survey

Abstract Background. This study aims to investigate the clinical use of the main Alzheimer’s disease (AD) biomarkers in patients with mild cognitive impairment (MCI) by examining the beliefs and preferences of clinicians and biomarker experts of the European Alzheimer’s Disease Consortium (EADC).Methods. Out of 306 contacted EADC professionals, 150 (101 clinicians, 43 biomarker experts, and 6 falling into other categories) filled in an online survey from May to September 2020. The investigated biomarkers were: medial temporal lobe atrophy score (MTA) on structural MRI, typical AD (i.e. temporoparietal and posterior cingulate) hypometabolism on FDG-PET, CSF (Aβ42, p-tau, t-tau), amyloid-PET and tau-PET.Results. Despite the abnormal accumulation of amyloid rather than tau was deemed by the majority of responders as the initial cause of AD, responders did not show a clear preference for amyloid-PET. The most widely used biomarker is MTA (77% of responders reported to use it at least frequently), followed by Aβ42, p-tau, t-tau levels in CSF (45%), typical AD hypometabolism on FDG-PET (32%), amyloid-PET (8%), and tau-PET (2%). Imaging and CSF biomarkers were found to be widely used to support the etiological diagnostic process in MCI, while APOE genotyping was performed only in a minority of patients. CSF is considered the most valuable biomarker in terms of additional diagnostic value, followed by amyloid-PET, tau-PET, and typical AD hypometabolism on FDG-PET. The combination of amyloidosis and neuronal injury biomarkers is associated with the highest diagnostic confidence in an etiological diagnosis of AD in MCI, while MTA alone was perceived as the less reliable biomarker.Conclusions. Biomarkers are widely used across Europe for the diagnosis of MCI. Overall, we observed that CSF is currently considered as the most useful biomarker, followed by amyloid-PET. Moreover, the use of molecular imaging (i.e. amyloid-PET and tau-PET) in the diagnostic work-up of MCI patients is increasing over time.