Supplementary Material for: Cognition and Incident Dementia Hospitalization: Results from the Atherosclerosis Risk in Communities Study

<b><i>Background/Aims:</i></b> Cognitive decline is a defining feature of dementia. We sought to determine if a single baseline cognitive test score or change in test score over time is more strongly associated with risk of dementia hospitalization. We also sought to compare short- and long-term dementia risk. <b><i>Methods:</i></b> Prospective cohort study of 9,399 individuals from the Atherosclerosis Risk in Communities Study (median 10 years of follow-up). Cognition was assessed at two time points (6 years apart) using three tests: Delayed Word Recall Test (DWRT), Digit Symbol Substitution Test (DSST), and Word Fluency Test. Dementia hospitalizations were determined using ICD-9 codes. <b><i>Results:</i></b> Baseline cognitive test scores were associated with both short-term and long-term risk of dementia. The association of 6-year change in cognitive test score with dementia risk was stronger than that of individual test scores at a single visit [change from highest to lowest tertile, DWRT: hazard ratio = 6.45 (95% confidence interval = 1.80–23.08); DSST: hazard ratio = 10.94 (95% confidence interval = 3.07–38.97)]. <b><i>Conclusions:</i></b> In this community-based population, 6-year changes in cognitive scores were more strongly associated with risk of incident dementia hospitalization than baseline scores, although single DWRT and DSST scores were predictive. Our findings support the contention that cognitive changes may precede clinical dementia by a decade or more.

**背景与目的**：认知衰退是痴呆的标志性特征。本研究旨在明确：单次基线认知测试得分，抑或是随时间推移的测试得分变化，与痴呆住院风险的关联更强；同时本研究还对短期与长期痴呆风险进行了比较。
**研究方法**：本研究为针对社区动脉粥样硬化风险研究（Atherosclerosis Risk in Communities Study）的前瞻性队列研究，共纳入9399名受试者，中位随访时长为10年。认知评估在两个间隔6年的时间点开展，采用三项测试：延迟词语回忆测试（Delayed Word Recall Test，DWRT）、数字符号替换测试（Digit Symbol Substitution Test，DSST）以及词语流畅性测试（Word Fluency Test）。痴呆住院病例通过ICD-9编码进行判定。
**研究结果**：基线认知测试得分与痴呆的短期及长期风险均存在显著关联。认知测试得分6年变化量与痴呆风险的关联强度，高于单次随访的单项测试得分[由最低三分位至最高三分位的变化：DWRT的风险比（hazard ratio, HR）=6.45，95%置信区间（confidence interval, CI）=1.80~23.08；DSST的HR=10.94，95%CI=3.07~38.97]。
**研究结论**：在该社区人群中，尽管单次DWRT与DSST得分具备预测价值，但认知得分6年的变化量与新发痴呆住院风险的关联强度显著高于基线得分。本研究结果支持“认知变化可能在临床痴呆出现前十余年就已显现”这一学术观点。