Differential dementia risks of motoric cognitive risk syndrome and mild cognitive impairment among older adults in China: a 7-year cohort study.

Background: Mild cognitive impairment (MCI) and motoric cognitive risk syndrome (MCR) are two pre-dementia stages, which may exist independently or concurrently, and both increase the risk of dementia. The association between MCI, MCR, and their co-occurrence with dementia risk in the elderly Chinese population remains unclear.

Objective: This study aims to explore the relationship of MCI, MCR, and their co-occurrence with the incidence of dementia among the elderly population in China, based on a nationwide large-scale survey.

Methods: A total of 2,411 elderly individuals from the China Health and Retirement Longitudinal Study (CHARLS) were included in this study. At baseline in 2011, all eligible participants were categorized into four groups: CHI (cognitively healthy individuals) group, MCI (individuals with MCI alone) group, MCR (individuals with MCR alone) group, and MCI + MCR (individuals with both MCI and MCR) group. After a 7-year follow-up, logistic regression models were used to analyze the longitudinal association between pre-dementia stages and the onset of dementia.

Results: At baseline, the prevalence rates were 14.5% for MCI group, 9.8% for MCR group, and 2.2% for MCI + MCR group. The median total cognitive scores at baseline were 16 points for both CHI group and MCR group, 9 points for MCI group, and 8.7 points for MCI + MCR group (P < 0.001). After 7 years of follow-up, the cognitive scores remained unchanged in MCI group, decreased by 1 point in both the CHI group and MCI + MCR group, and decreased by 2 points in MCR group (P < 0.001). The 7-year dementia incidence was 4.8%. Multivariate logistic regression model showed that the risk of dementia was significantly associated with MCI (OR = 2.319, 95%CI:1.420-3.785, P < 0.001), MCR (OR = 2.488, 95%CI:1.441-4.294, P = 0.001), and MCI + MCR (OR = 3.226, 95% CI:1.340-7.762, P = 0.009).

Conclusion: Both MCI and MCR were associated with an increased risk of dementia, and the co-occurrence of MCI and MCR conferred a higher risk of dementia. Although the MCR group showed no significant baseline cognitive impairment, their subsequent cognitive decline and dementia risk were higher than those of the MCI group. Therefore, promoting MCR screening in China's primary healthcare system may be more feasible than MCI screening, which could help in early identification of high-risk populations and the implementation of targeted interventions to delay or prevent the onset of dementia.