Objective: To explore the predictive value of baseline cognitive score and olfactory function in conversion from mild cognitive impairment (MCI) to dementia.

Methods: The subjects were 57 patients initially diagnosed of MCI in Memory Disorder Outpatient Department affiliated to the Department of Neurology, Renji Hospital, Shanghai Jiao Tong University School of Medicine from March 2011 to September 2012. The cognitive function-related neuropsychological tests including Mini-mental State Examination (MMSE), Instrumental Activity of Daily Living (IADL), Montreal cognitive assessment (MoCA), Neuropsychiatric Inventory (NPI) and 12-item Cross-Cultural Smell Identification Test were used. Prospective follow-up was performed for 2 years. During 2 years, the regular neuropsychological tests and olfactory assessment were conducted. Within 2 years, MCI patients who converted to dementia were classified into MCI conversion group, and those who did not convert to dementia were classified into MCI stable group. Logistic regression analysis was used to analyze the independent predictors of conversion of MCI to dementia within 2 years.

Results: There were no significant differences in baseline age, sex, years of education and body mass index (BMI) between the MCI transformation group and the MCI stable group (P > 0.05). The baseline MMSE score, MoCA score, IADL score and olfactory score in the MCI conversion group were all lower than those of the MCI stable group, and the difference was statistically significant (P < 0.001); the NPI score was also lower than that of the MCI stable group, but the difference was not statistically significant (P = 0.364). During the follow-up period of 2 years, 18 of the 57 MCI patients were converted to dementia, and the
conversion rate was 31.6%. The MMSE score, MoCA score, IADL score and olfactory score of the MCI group were still lower than those of the MCI stable group in the second year of follow-up, and the difference was statistically significant (P < 0.001). Logistic regression analysis showed that age, BMI, years of education, MMSE score, IADL score, MoCA score, NPI score, and olfactory score were not independent predictors of conversion from MCI to dementia (P > 0.05).

Conclusion: Neuropsychological tests and olfactory assessment may be potential predictors of conversion from MCI to dementia in patients with MCI, but it is still necessary to expand the sample size for further validation.