Mayeda Elizabeth R, Haan Mary N, Yaffe Kristine, Kanaya Alka M, Neuhaus John
Departments of *Epidemiology and Biostatistics †Neurology ‡Psychiatry §Internal Medicine, University of California, San Francisco, CA.
Alzheimer Dis Assoc Disord. 2015 Jul-Sep;29(3):206-12. doi: 10.1097/WAD.0000000000000083.
Estimating effects of diabetes on cognitive change among older Mexican Americans is important, yet challenging, because diabetes and cognitive decline both predict mortality, which can induce survival bias. Older Mexican Americans in the Sacramento Area Latino Study on Aging (n=1634) completed Modified Mini-Mental State Exams (3MSE) and diabetes assessments up to 7 times (from 1998 to 2007). We examined baseline and new-onset diabetes and cognitive decline with joint longitudinal-survival models to account for death. At baseline, 32.4% of participants had diabetes and 15.8% developed diabetes during the study. During the study period, 22.8% of participants died. In joint longitudinal-survival models, those with baseline diabetes experienced faster cognitive decline (P=0.003) and higher mortality (hazards ratio=1.88; 95% confidence interval, 1.48-2.38) than those without diabetes. Cognitive decline and mortality were similar for those with new-onset diabetes and those without diabetes. For a typical person, 3MSE scores declined by 2.3 points among those without diabetes and 4.3 points among those with baseline diabetes, during the last 6 years of study. Ignoring the impact of death yielded a 17.0% smaller estimate of the effect of baseline diabetes on cognitive decline. Analyses that overlook the association between cognitive decline and mortality may underestimate the effect of diabetes on cognitive aging.
评估糖尿病对老年墨西哥裔美国人认知变化的影响既重要又具有挑战性，因为糖尿病和认知能力下降都预示着死亡率，这可能会导致生存偏差。萨克拉门托地区拉丁裔老龄化研究（n = 1634）中的老年墨西哥裔美国人完成了改良的简易精神状态检查（3MSE）和多达7次的糖尿病评估（从1998年到2007年）。我们使用联合纵向生存模型来考虑死亡因素，研究了基线糖尿病和新发糖尿病与认知能力下降的情况。在基线时，32.4%的参与者患有糖尿病，15.8%的参与者在研究期间患上糖尿病。在研究期间，22.8%的参与者死亡。在联合纵向生存模型中，与无糖尿病者相比，基线糖尿病患者的认知能力下降更快（P = 0.003），死亡率更高（风险比 = 1.88；95%置信区间，1.48 - 2.38）。新发糖尿病者和无糖尿病者的认知能力下降和死亡率相似。对于一个典型的人来说，在研究的最后6年中，无糖尿病者的3MSE得分下降了2.3分，基线糖尿病患者下降了4.3分。忽略死亡的影响会使基线糖尿病对认知能力下降影响的估计值小17.0%。忽视认知能力下降与死亡率之间关联的分析可能会低估糖尿病对认知衰老的影响。
