Editorial introduction to the special issue on biomarker-based diagnosis of Alzheimer's disease: A synthesis of the commentaries.

We introduce a special issue of the Journal of Neuropsychology dedicated to a recent paradigm shift in Alzheimer's disease diagnosis. Joint workgroups from the (US) National Institute on Aging and the Alzheimer's Association (NIA-AA) recently issued policy guidelines reclassifying Alzheimer's disease as a biological entity. These guidelines shift the onus of diagnosis in favour of protein biomarkers, relegating cognitive symptoms (e.g. subjective memory and language disorders) as supportive rather than core features. We invited experts in the study of Alzheimer's disease and Related Disorders (ADRDs) to express their views on this paradigmatic shift in dementia management. In this editorial, we synthesize some of the main points advanced in the commentaries. Contributors identified the promise of blood-based biomarker testing for improving equitable detection of dementia in large swathes of the world population. This enthusiasm was tempered by concerns about the biomarker-only diagnostic approach, including the potential for significant harm (e.g. stigma, depression, suicide) caused by labelling asymptomatic older adults who might otherwise never behaviourally express the underlying disease pathology.