Hall C B, Lipton R B, Sliwinski M, Stewart W F
University of Connecticut Health Center, Department of Community Medicine and Health Care Division of Biostatistics, MC-6325, Farmington, CT 06030-6325, USA.
Stat Med. 2000;19(11-12):1555-66. doi: 10.1002/(sici)1097-0258(20000615/30)19:11/12<1555::aid-sim445>3.0.co;2-3.
Dementia is characterized by accelerated cognitive decline before and after diagnosis as compared to normal ageing. Determining the time at which that rate of decline begins to accelerate in persons who will develop dementia is important both in describing the natural history of the disease process and in identifying the optimal time window for which treatments might be useful. We model that time at which the rate of decline begins to accelerate in persons who develop dementia relative to those who do not by using a change point in a mixed linear model. A profile likelihood method is proposed to draw inferences about the change point. The method is applied to data from the Bronx Ageing Study, a cohort study of 488 initially non-demented community-dwelling elderly individuals who have been examined at approximately 12-month intervals over 15 years. Cognitive function was measured using the Buschke Selective Reminding test, a memory test with high reliability and known discriminative validity for detecting dementia. We found that the rate of cognitive decline as measured by this test in this cohort increases on average 5.1 years before the diagnosis of dementia.
与正常衰老相比，痴呆症的特征是在诊断前后认知能力加速下降。确定痴呆症患者认知能力下降速度开始加快的时间，对于描述疾病进程的自然史以及确定治疗可能有效的最佳时间窗口都很重要。我们通过使用混合线性模型中的变化点，对痴呆症患者相对于非痴呆症患者认知能力下降速度开始加快的时间进行建模。提出了一种轮廓似然方法来推断变化点。该方法应用于布朗克斯衰老研究的数据，这是一项对488名最初无痴呆症的社区居住老年人进行的队列研究，他们在15年中每隔约12个月接受一次检查。使用布施克选择性提醒测试来测量认知功能，这是一种对检测痴呆症具有高可靠性和已知判别效度的记忆测试。我们发现，在该队列中，通过此测试测量的认知能力下降速度在痴呆症诊断前平均5.1年开始增加。
