Conversion pattern and predictive factor of mild cognitive impairment in elderly Koreans

Objective: We aimed to understand conversion characteristics of mild cognitive impairment (MCI) in elderly Koreans. Methods: We analyzed clinical data of 760 individuals who participated in a two-year follow-up study. Neuropsychological assessments and clinical examination were conducted in the follow-ups. Logistic regression model was used to estimate predictive risk factors of MCI conversion. Result: The participants at baseline (n = 760) represented 462 cognitively normal individuals (60.8%), 286 individuals with MCI (37.6%), and 12 individuals with dementia (1.6%). Among the cognitively normal individuals (n = 462), 108 (23.4%) progressed to MCI during the two-year follow-up period, including 92 with amnestic mild cognitive impairment (aMCI; 19.9%) and 16 with non-amnestic mild cognitive impairment (non-aMCI; 3.5%). Interestingly, 3.7% of participants with aMCI converted to non-aMCI, while 45.5% of participants with non-aMCI converted to aMCI. Moreover, a higher proportion of non-aMCI (27.3%) reverted to a cognitively normal state, compared to aMCI participants (18.6%), indicating that non-amnestic cognitive impairment is more unstable than amnestic cognitive impairment, and probably converges toward aMCI. Additionally, we found that weight loss was associated with incident MCI and future MCI. Weight loss was negatively correlated with Clinical Dementia Rating (p = 0.005), and significantly associated with a higher risk of MCI conversion from a cognitively normal state (OR = 1.10, 95% CI: 1.00-1.21, p = 0.042). Conclusion: This study supports that non-amnestic MCI is prone to converge toward amnestic MCI, and the elderly people with weight loss are at risk for developing cognitive decline.