marginal significanceP = 0.0963
Although the overall test for deviation from linearity approached marginal significance ( P = 0.0963), the noncontributory role of nonlinear components, combined with linear regression results (Model 3: β = 0.068, 95% CI 0.030–0.105, P < 0.001), confirmed a continuous linear association between CumAIP and dementia scores, laying the foundation for subsequent dose–response relationship analyses.