Olfactory dysfunction in multiple sclerosis

Background: Multiple sclerosis (MS) is a common chronic neurological disease that causes disability. MS can have various clinical manifestations, one of which is olfactory dysfunction. In clinical practice, olfactory disturbances are usually underdiagnosed. The aim of our study is to assess olfactory function and its relationship with MS disease duration, disability and cognition. Method: We assessed 31 MS patients and 24 healthy controls matched in sex and age at our MS outpatient clinic of the Istanbul Education and Research Hospital Neurology Department. Each subject was interviewed to obtain demographic data. The Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test and Montreal Cognitive Assessment (MOCA) were applied to each participant. Results: The CCCRC test scores of the MS patients were lower than those in the control group (p < 0.05). Patients with a longer disease duration and more frequent attacks had lower CCCRC scores (p < 0.05). The Expanded Disability Status Scale scores had no correlation with the CCCRC test scores. The MOCA score was positively correlated with all domains of the olfactory test scores. Conclusion: This study supports the presence of olfactory dysfunction in early stages of MS and the correlation of cognitive impairment with olfactory dysfunction, even in the early stages of the disease in young and less physically- disabled patients. The assessment of olfaction may be helpful as a surrogate method for tracking disease progression in patients over time.