Olfactory and gustatory dysfunctions as early markers in Parkinson’s disease: clinical correlation and neurobiological implications

Abstract

Parkinson’s disease is characterized by a progressive neurodegenerative process in which non-motor symptoms may precede classic clinical manifestations for several years. In this context, olfactory and gustatory dysfunctions have been investigated as potential early markers of the prodromal phase of the disease. This study aimed to analyze the relationship between olfactory and gustatory sensory alterations and the early development of Parkinson’s disease. This is a systematic literature review conducted in the PubMed, Scopus, SciELO, and EBSCOhost databases, including studies published between 2014 and 2026. Previously defined inclusion and exclusion criteria were applied, resulting in the final selection of 21 studies for analysis. The results showed that olfactory dysfunction, especially hyposmia, is relevantly associated with an increased risk of developing the disease and may precede clinical diagnosis by several years. Gustatory alterations were also identified, although less frequently, often coexisting with olfactory deficits. It is concluded that olfactory and gustatory dysfunctions have potential as prodromal markers of Parkinson’s disease and may contribute to earlier diagnostic strategies when associated with other biomarkers.