Olfactory Dysfunction in Parkinson's Disease, Its Functional and Neuroanatomical Correlates.

Parkinson's disease (PD) is known for its motor alterations, but the importance of non-motor symptoms (NMSs), such as olfactory dysfunction (OD), is increasingly recognized. OD may manifest during the prodromal period of the disease, even before motor symptoms appear. Therefore, it is suggested that this symptom could be considered a marker of PD.