Applying the IWG research criteria in clinical practice: feasibility and ethical issues.

One of the strengths of the IWG criteria was to reconceptualize the diagnosis of AD, from a clinical-pathologic diagnosis to a clinical-biologic one, which can be performed in vivo. The diagnosis should, therefore, be implemented in the clinical stage of the disease, relying on the essence of the new IWG diagnostic criteria in the recognition of this dual aspect of AD: a specific clinical presentation that is related to a well-defined underlying pathology. Biomarkers measured by PET or CSF correlate with high sensitivity and specificity with AD pathologic features; episodic memory properly measured also presents high specificity to detect patients who develop AD dementia, and clinical studies have demonstrated that these criteria applied in a clinical setting present good specificity, making feasible a diagnosis in the prodromal stage of the disease. From an ethical perspective, the governing principle for early prodromal diagnosis should be autonomy, because the decision of wishing to know or not to know should be performed individually by a competent individual. Furthermore, the potential benefit of an early diagnosis may be mediated through an autonomous decision.