Executive function predicts survival in Alzheimer disease: a study in Shanghai

We aimed to investigate the natural history of Alzheimer's disease (AD) and the risk factors associated with survival. We performed a 5-year retrospective cohort study on 467 consecutive outpatients clinically diagnosed with AD and treated between January 1, 2003, and December 31, 2006, at Huashan Hospital, Shanghai, China. The primary endpoint in this study was survival. At baseline, we evaluated the patients' demographic characteristics and neuropsychological characteristics, comorbid conditions, neuroimaging findings, complications, and neurological signs. Among the 467 patients, 398 survived. Male gender, age, and disease severity were associated with mortality. Survival analysis using the proportional hazard model with adjustments for gender, age, and disease stage revealed that the cognition factors that predicted longer survival included high total score [hazard ratio (HR), 0.85; 95% confidence interval (CI), 0.76-0.96] and sub-scores in the verbal fluency test (animals, vegetables, and fruits). The presence of at least 1 complication was an independent factor predictive of a decreased lifespan (HR, 5.55; 95% CI, 1.91-16.13). In AD patients, presence of complications was an indicator of poor survival, while good performance in assessments of executive function, such as the verbal fluency test and Stroop test, at baseline was associated with longer survival.