An observational study in the US suggests that prolonged sleep duration may be a marker of early neurodegeneration and hence a useful clinical tool to identify those at a higher risk of progressing to clinical dementia within 10 years. The study collected self-reported total hours of sleep in 2,457 participants (mean age 72 ± 6 years, 57% women) as a 3-level variable: 9 hours (long). There were 234 cases of all-cause dementia over 10 years of follow-up. In multivariable analyses, prolonged sleep duration was associated with an increased risk of incident dementia (hazard ratio [HR] 2.01). These findings were driven by persons with baseline mild cognitive impairment (HR 2.83) and persons without a high school degree (HR 6.05). Transitioning to sleeping >9 hours over a mean period of 13 years before baseline was associated with an increased risk of all-cause dementia (HR 2.43) and clinical Alzheimer disease (HR 2.20). Relative to sleeping 6–9 hours, long sleep duration was also associated cross-sectionally with smaller total cerebral brain volume and poorer executive function. Studies examining self-reported sleep duration and dementia risk in older populations have had mixed findings: some suggested that sleeping for shorter periods associated with increased dementia risk, while others found long-duration (>9 hours) sleep to be associated with the greater risk. Source: http://www.neurology.org/
美国一项观察性研究提示，睡眠持续时间延长可能是早期神经退变的标志，因此是识别在10年内发展为临床痴呆高风险者有用的临床指标。该研究收集了2,457名参与者（平均年龄72±6岁，57％女性）自我报告的总睡眠时间作为3级变量：<6小时（短），6-9小时（参照）和> 9小时（长）。在10年的随访中，有234例全因痴呆症。经多变量分析，睡眠持续时间延长与痴呆风险增加相关（风险比 2.01）。这些发现主要是由具有轻度基线认知障碍（风险比2.83）和无高中学历者（风险比6.05）所致。在基线前平均13年间过渡到睡眠> 9小时与全因痴呆（风险比2.43）和临床阿尔茨海默病（风险比2.20）的风险增加相关。相对于睡眠6-9小时，睡眠持续时间长也与横断面研究中总脑体积较小和执行功能较差相关。自我报告的睡眠持续时间与老年痴呆风险的研究结果并不一致：一些提示睡眠时间较短与痴呆风险增加有关，而其他人则发现长时间睡眠（> 9小时）与更大的风险相关。来源：http://www.neurology.org/