Intraindividual variability in cognitive function in older people in the English Longitudinal Study of Ageing: modelling risk factors using a mixed-effects beta-binomial model
Intraindividual variability in cognitive function in older people in the English Longitudinal Study of Ageing: modelling risk factors using a mixed-effects beta-binomial model
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DOI：
10.1101/2022.06.01.22275869
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发表时间：
2022-06
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影响因子：
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通讯作者：
R. A. Parker;K. Tilling;G. Terrera;J. Barrett
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作者：
R. A. Parker;K. Tilling;G. Terrera;J. Barrett
老年人的认知功能对生活质量和身心健康有巨大影响。虽然大多数关于老年认知的研究都集中在平均水平上，但有一些证据表明，认知功能差异很大的个体可能与功能变化较小的个体具有不同的风险因素和结果。现有的方法来调查这种个体内变异性（IIV）通常涉及从拟合均值周围的残差中得出每个人的汇总统计量。然而，这种方法忽略了抽样的可变性，禁止探索与时变因素的关联，并受到下限和上限效应的影响。为了解决这个问题，我们拟合了一个混合效应的位置尺度β-二项式模型，以估计平均每次试验的概率和IIV在一个单词回忆测试与英语纵向研究老化（艾尔莎）。在对平均表现进行调整后，在对7个（平均值：3.4）波中观察到的9，873人进行的分析中，我们发现IIV更大：年龄较大;教育程度较低;女性;日常生活活动困难较多;在较晚的队列中;以及当面试官记录可能影响测试的问题时。我们的研究确定了认知表现差异更大的群体，这对他们的日常功能和护理有影响。需要进一步开展工作，以确定这对未来健康结果的影响。
Cognitive functioning in older age has a huge impact on quality of life and physical and mental health. Whilst most research in cognition in older age has focussed on mean levels, there is some evidence that individuals with cognitive functioning that varies a lot around this may have different risk factors and outcomes to those with less variable functioning. Existing approaches to investigate such intraindividual variability (IIV) typically involve deriving a summary statistic for each person from residual error around a fitted mean. However, such methods ignore sampling variability, prohibit the exploration of associations with time-varying factors, and are biased by floor and ceiling effects. To address this, we fitted a mixed-effects location scale beta-binomial model to estimate average per-trial probability and IIV in a word recall test with the English Longitudinal Study of Aging (ELSA). After adjusting for mean performance, in an analysis of 9,873 individuals observed across 7 (mean: 3.4) waves we found IIV to be greater: at older ages; with lower education; in females; with more difficulties with activities of daily living; in later cohorts; and when interviewers recorded issues which may have affected the tests. Our study identifies groups with more varying cognitive performance, which has implications for their daily functioning and care. Further work is needed to identify the impact of this for future health outcomes.