Early Markers of Alzheimer Disease

巴尔的摩老龄化纵向研究（BLSA）成立于1958年，是美国和世界上最古老的老龄化前瞻性研究之一。BLSA的使命是了解当人们变老时会发生什么，以及如何区分由于衰老和疾病或其他原因造成的变化。 我们的大多数分析都是考察绩效水平随时间的变化轨迹。然而，我们怀疑在表现的不一致性中有重要的信息，并且更大的个体差异可能与随后的认知障碍和痴呆有关。在巴尔的摩老龄化纵向研究（平均SD年龄= 69.90 - 8.92）参与者的病例对照样本中，我们根据初始测试时的年龄和性别将135名临床诊断为痴呆的参与者与135名非痴呆的参与者进行了匹配。认知功能进行了检查，从最初的评估到5年前的认知功能障碍（平均评估= 3.03）的记忆，执行功能，注意力，语言和整体精神状态的表现。与未受损的个体相比，诊断为痴呆的个体在估计的认知障碍发作前至少5年在注意力、执行功能、语言和语义记忆的测量上具有更大的变异性，这可能表明适应不良的认知功能。然而，痴呆症病例的视觉记忆变异性比未受损组小，这可能表明这些病例在学习上有更多的困难。这些结果表明，性能变异指数超过每年或两年一次的访问可能是有用的，在识别早期迹象，随后的认知功能障碍。

The Baltimore Longitudinal Study of Aging (BLSA) was established in 1958 and is one the oldest prospective studies of aging in the USA and the world. The mission of the BLSA is to learn what happens to people as they get old and how to sort out changes due to aging and from those due to disease or other causes. Most of our analyses examine the trajectories of performance levels over time. However, we have suspected that there is important information in the inconsistencies in performance, and that greater within individual variability might be associated with subsequent cognitive impairment and dementia. In a case-control sample of Baltimore Longitudinal Study of Aging (mean SD age = 69.90 8.92) participants, we matched 135 clinically diagnosed demented participants with 135 non-demented participants based on age at initial testing and sex. Cognitive performance was examined using measures of memory, executive function, attention, language, and global mental status performance from initial assessment to 5 years before cognitive impairment (mean assessments = 3.03). Compared with unimpaired individuals, individuals diagnosed with dementia had greater variability on measures of attention, executive function, language, and semantic memory at least 5 years before the estimated onset of cognitive impairment, which may indicate maladaptive cognitive functioning. The dementia cases, however, had less variability on visual memory than the unimpaired group, which may suggest that these cases had more difficulty learning. These results suggest that performance variability indexed over annual or biennial visits may be useful in identifying early signs of subsequent cognitive impairment.