Figure 3.

Higher cognitive abilities, reserved for specific brain regions, are required to identify odors, which, in neurodegenerative diseases, manifest common neuroanatomical defects, up to altered neurotransmission patterns of olfactory pathways, such as for the deposition and accumulation of molecules such as α-synuclein, TDP-43, hyperphosphorylated tau protein, and β-amyloid protein. An important aspect for the clinician, and particularly the otolaryngologist, is the performance of olfactory testing in patients who manifest olfactory disorders. In this context, individuals affected by neurodegenerative diseases should be able to perform non-cognitively complex, short-term tests with few tasks. For this reason, differential diagnosis is recommended for common nasal disorders frequently associated with anosmia or other olfactory disorders so that such disorders can be identified early, as a prodromal symptom of neurodegenerative diseases.