Olfactory Dysfunction: An early indicator of parkinson's disease

• Clinicians demonstrate a lack of interest to enquire about testing for anosmia. • Evidence indicates the origin of Parkinson's disease (PD) in the olfactory brain. • Relationship between PD and rhinitis affecting the sense of smell. • An impaired sense of smell increases the likelihood of developing PD. • A possible biomarker for early PD detection. Parkinson's disease (PD) is the foremost movement condition globally. It is marked by a decline in olfactory function and a reduction in neurotrophic factors, especially α-synuclein, associated with synaptic activity and degeneration. This review seeks to clarify the cerebral pathways implicated in the initiation and advancement of PD. Anosmia has been identified as a risk factor for the subsequent development of PD. Thus, olfactory impairment is suggested as an initial sign or biomarker of PD. Furthermore, it investigates the correlation between the stomach and the brain, the influence of olfactory perception, and other factors that could hinder the advancement of PD, such as smoking, coffee intake, and particular therapies. We proposed that if anosmia is diagnosed in a patient, it may indicate PD, allowing us to initiate preventive medication for Parkinsonism.