To the Editor Rosebud and colleagues1 reported on a longitudinal study strengthening the idea that olfactory impairment has potential to be a biomarker for diagnosing mild cognitive impairment (MCI) and Alzheimer disease (AD) or early detection for cognitively normal elderly individuals who would likely progress to MCI or AD. The underlying mechanism may be due to, at least in part, the involvement of AD neuropathological processes in both the olfactory bulb and other cerebral areas that are related to olfactory function.
Zhang J. Olfactory Loss—On the Road to Potential Diagnosis Criteria of Alzheimer Disease. JAMA Neurol. 2016;73(6):761-762. doi:10.1001/jamaneurol.2016.0326