Department of Psychology and Centre for Brain Science, University of Essex, Colchester, Essex, United Kingdom.
Department of Behavioral and Brain Sciences, University of Pavia, Pavia, Italy.
PLoS One. 2023 Nov 29;18(11):e0290635. doi: 10.1371/journal.pone.0290635. eCollection 2023.
Stress and normal ageing produce allostatic load, which may lead to difficulties with cognition thereby degrading quality of life. The current study's objective was to assess whether ageing and cumulative stress interact to accelerate cognitive decline. With 60 participants, Marshall et al. found that ageing and cumulative stress interact significantly to impair working memory performance in older adults, suggesting vulnerability to the cumulative effects of life events beyond 60 years old. To replicate and extend this finding, we increased the sample size by conducting 3 independent studies with 156 participants and improved the statistical methods by conducting an iterative Bayesian meta-analysis with Bayes factors. Bayes factors deliver a more comprehensive result because they provide evidence for either the null hypothesis (H0), the alternative hypothesis (H1) or for neither hypothesis due to evidence not being sufficiently sensitive. Young (18-35 yrs) and older (60-85 yrs) healthy adults were categorised as high or low stress based on their life events score derived from the Life Events Scale for Students or Social Readjustment Rating Scale, respectively. We measured accuracy and reaction time on a 2-back working memory task to provide: a) Bayes factors and b) Bayesian meta-analysis, which iteratively added each study's effect sizes to evaluate the overall strength of evidence that ageing, cumulative stress and/or the combination of the two detrimentally affect working memory performance. Using a larger sample (N = 156 vs. N = 60) and a more powerful statistical approach, we did not replicate the robust age by cumulative stress interaction effect found by Marshall et al.. The effects of ageing and cumulative stress also fell within the anecdotal range (⅓<BF<3). We therefore conclude that there was inconclusive statistical evidence, as measured with a life events scale, that ageing and cumulative life stress interact to accelerate cognitive decline.
压力和正常衰老会产生适应负荷，这可能导致认知困难，从而降低生活质量。本研究的目的是评估衰老和累积压力是否相互作用，加速老年人的认知能力下降。马歇尔等人对 60 名参与者进行了研究，发现衰老和累积压力显著相互作用，损害了老年人的工作记忆表现，这表明老年人对 60 岁以后生活事件的累积效应很脆弱。为了复制和扩展这一发现，我们通过 3 项独立研究增加了 156 名参与者的样本量，并通过迭代贝叶斯元分析和贝叶斯因子改进了统计方法。贝叶斯因子提供了更全面的结果，因为它们提供了支持零假设（H0）、替代假设（H1）或由于证据不够敏感而不支持任何假设的证据。根据他们的生活事件评分，将年轻（18-35 岁）和老年（60-85 岁）健康成年人分为高或低压力组，该评分分别来自学生生活事件量表或社会再适应评定量表。我们在 2 背工作记忆任务中测量了准确性和反应时间，以提供：a）贝叶斯因子和 b）贝叶斯元分析，该分析迭代地添加了每个研究的效应大小，以评估衰老、累积压力以及两者结合对工作记忆表现产生不利影响的总体证据强度。使用更大的样本量（N=156 与 N=60）和更强大的统计方法，我们没有复制马歇尔等人发现的稳健的年龄与累积压力相互作用效应。衰老和累积压力的影响也在轶事范围内（⅓<BF<3）。因此，我们得出结论，没有确凿的统计证据表明，正如生活事件量表所测量的那样，衰老和累积生活压力相互作用会加速认知能力下降。
