Tau Protein Detection in Anosmic Alzheimer’s Disease Patient’s Nasal Secretions

Introduction In the recent years, olfactory disorders are described in a wide range of neurological disorders such as Alzheimer’s disease. Neurofibrillary tangles, one of the hallmark pathologic indicators of Alzheimer’s disease, have been identified within the olfactory bulb, olfactory tract, anterior olfactory nucleus, entorhinal cortex, and amygdala. Severity of dementia has been correlated with the number of neurofibrillary tangles within such. Materials and Methods The study was performed from the ENT Clinic of the University of Siena and from the University of Rome BTor Vergata^ laboratory; data were collected and analyzed by the ENT Clinic of the Catholic University of the Sacred Hearth, Rome. Twenty-five adult subjects with median age of 72.3 years were enrolled. Thirteen adult subjects with median age of 26.1 years, with neither history of nasal and/or olfaction and neurological disease, were enrolled as control group. All patients were studied through the Sniffin’ Sticks® olfactory test, performing the threshold, detection, and identification tests. All these tests were preceded by rhinomanometry and sensitized with nasal decongestion, in order to allow a correct odorants’ diffusion to olfactory epithelium. Results A significative tau protein and phosphorylated tau protein levels were detected in almost all the anosmic patients. All the controls were negative in tau protein dosage except for one in which a phosphorylated tau protein level of 70–90 pg/ ml was found. Conclusions Our series, even if the present is a preliminary study, give an evidence about tau protein presence both in the naïve and in the phosphorylated form in nasal secretion obtained from Alzheimer’s disease patients.