MAPT and tauopathy: This approach is crucial to unveil the diversity of proteins involved in olfaction and identify molecular determinants in the early development of some NDs characterized by cognitive deficits, such as tauopathies, tuberous sclerosis complex, hemimegaloencephaly and cortical dysplasia focal type II, characterized by phosphorylated tau, such as Down syndrome not in childhood but in early adult life, for which olfactory proteins have not been systematically studied.