Validation of Iranian Smell Identification Test for screening of mild cognitive impairment and Alzheimer’s disease

Abstract

Background

According to the World Alzheimer Report 2019, an estimated 50 million people worldwide are living with dementia. The smell test is a method for early detection of Alzheimer’s disease (AD) as an inexpensive, simple, and noninvasive screening tool. This study aimed to evaluate the accuracy of the Iran Smell Identification Test (Iran-SIT) in discriminating patients with AD, with mild cognitive impairment (MCI), and the healthy subjects.

Methods

In this study, 42 patients with AD, 33 with MCI, and 32 healthy controls were recruited from the referral Memory Clinic of Tehran University of Medical Sciences. The olfactory function was examined with six odors through Iran-SIT.

Results

We found a significant difference among the olfactory function in subjects with normal cognitive status, that of those with MCI and those with AD (p < 0.001). The cutoff point for the diagnosis of AD was (sensitivity and specificity were, respectively, 85.7 and 90.8%), and (Sensitivity and specificity were, respectively, 93.9 and 100%) for MCI.

Conclusion

These results suggest that Iran-SIT is a valid biomarker and practical screening tool, with simple, inexpensive, and readily available for use in combination with neuropsychological tools and neuroimaging for early detection of AD.

Keywords:

• Alzheimer’s disease
• diagnostic accuracy
• early detection
• mild cognitive impairment (MCI)
• screening tool
• smell test

Acknowledgments

We are grateful to the patients, staff, and volunteers at the Yaadmaan Center of Excellence For Neurological, Memory & Cognitive Disorders. We are very grateful to Dr. Maryam Mohammadi, and Dr. Akram Farhadi, for their valuable guidance. Special thanks are owed to all who participated in our study with great patience and kindness.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.