Association of platelet count with incident motoric cognitive risk syndrome among Chinese adults aged 60 years or older: a national prospective cohort study

Background Motoric cognitive risk syndrome (MCR), defined by subjective cognitive complaints and slow gait in individuals without dementia, is a clinically relevant pre-dementia phenotype. Platelets are increasingly linked to inflammation, endothelial dysfunction, and neurovascular signaling, but the prospective association between platelet count and MCR remains unclear. Objective To examine whether baseline platelet count is associated with incident MCR among older Chinese adults. Methods We analyzed 2,246 participants aged 60 years or older from the China Health and Retirement Longitudinal Study who were free of MCR at baseline in 2011 and had platelet count and follow-up MCR data in 2013. Platelet count was modeled as a continuous variable per 100 × 10⁹/L increase and by quintiles, with the middle quintile as the reference. Multivariable logistic regression models were adjusted for sociodemographic characteristics, lifestyle factors, adiposity indicators, depressive symptoms, and major chronic diseases. Restricted cubic spline analysis was used to evaluate the dose-response pattern. Subgroup analyses and a sensitivity analysis excluding participants with baseline stroke were also conducted. Results During the 2-year follow-up, 264 participants (11.8%) developed MCR. In the fully adjusted model, each 100 × 10⁹/L increase in platelet count was associated with higher odds of incident MCR (odds ratio [OR] = 1.25, 95% confidence interval [CI]: 1.06–1.47; P = 0.007). Compared with the middle quintile, the fourth and fifth quintiles showed increased odds of MCR (Q4: OR = 1.62, 95% CI: 1.05–2.50; Q5: OR = 1.75, 95% CI: 1.14–2.69), whereas the lower quintiles were not statistically significant. Restricted cubic spline analysis indicated an overall association ( P = 0.022) without clear evidence of non-linearity ( P for non-linearity = 0.402). The association persisted after excluding participants with baseline stroke, and no statistically significant subgroup interactions were observed. Conclusions Among Chinese adults aged 60 years or older, higher baseline platelet count was prospectively associated with increased odds of incident MCR. Platelet count may represent a readily measured hematologic correlate of incident MCR; however, the observational design precludes causal or predictive interpretation. Studies with longer follow-up and platelet activation, inflammatory, coagulation, and neuroimaging markers are needed to clarify the underlying mechanisms. Clinical trial number Not applicable.