MAPT and Alzheimer disease: In fact, as a low-cost, non-invasive method of evaluating olfactory function, the assessment of OI ability, combined with global cognitive testing, has the potential to help clinicians identify persons who rarely transition to dementia (Devanand et al., 2019), thus helping practitioners decide whether to apply further diagnostic investigations, such as PET scans, which help reduce the burden and cost of clinical AD trials and as the first diagnostic tau radiotracer for use with PET was approved by the US Food and Drug Administration, further research is possible and warranted.