Aging is associated with reduced slow wave (SW) density (number SW/min in non-rapid-eye-movement sleep) and amplitude. It has been proposed that an age-related decrease in SW density may be due to a reduction in EEG amplitude instead of a decline in the capacity to generate SW. Here, we propose a data-driven approach to adapt SW amplitude criteria to age and sex. We predicted that the adapted criteria would reduce age and sex differences in SW density and SW characteristics but would not abolish them. A total of 284 healthy younger and older adults participated in one night of sleep EEG recording. We defined age- and sex-adapted SW criteria in a first cohort of younger (n=97) and older (n=110) individuals using a signal-to-noise ratio approach. We then used these age- and sex-specific criteria in an independent second cohort (n=77, 38 younger and 39 older adults) to evaluate age and sex differences on SW density and SW characteristics. After adapting SW amplitude criteria, we showed maintenance of an age-related difference for SW density whereas the sex-related difference vanished. Indeed, older adults produced less SW compared to younger adults. Specifically, the adapted SW amplitude criteria increased the probability of occurrence of low amplitude SW (<80µV) for older men especially. Our results thereby confirm an age-related decline in SW generation rather than an artefact in the detection amplitude criteria. As for the SW characteristics, the age- and sex-adapted criteria display reproducible effects across the two independent cohorts suggesting a more reliable inventory of the SW.

中文翻译：

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年龄和性别对睡眠慢波的影响是否只是脑电图振幅的问题？

衰老与慢波 (SW) 密度（非快速眼动睡眠中的 SW/min 数）和振幅降低有关。有人提出，与年龄相关的 SW 密度降低可能是由于 EEG 振幅的降低而不是产生 SW 的能力下降。在这里，我们提出了一种数据驱动的方法，使 SW 振幅标准适应年龄和性别。我们预测调整后的标准将减少 SW 密度和 SW 特征的年龄和性别差异，但不会消除它们。共有 284 名健康的年轻人和老年人参加了一晚的睡眠脑电图记录。我们使用信噪比方法在第一组年轻 (n=97) 和年长 (n=110) 个体中定义了适应年龄和性别的 SW 标准。然后，我们在独立的第二队列（n=77，38 个年轻人和 39 个老年人）来评估 SW 密度和 SW 特征的年龄和性别差异。在调整 SW 振幅标准后，我们​​显示 SW 密度与年龄相关的差异得以维持，而与性别相关的差异消失了。事实上，与年轻人相比，老年人产生的 SW 更少。具体来说，调整后的 SW 幅度标准尤其增加了老年男性发生低幅度 SW (<80µV) 的可能性。因此，我们的结果证实了 SW 生成与年龄相关的下降，而不是检测幅度标准中的人为因素。至于 SW 特征，年龄和性别适应标准在两个独立的队列中显示出可重复的影响，表明 SW 的清单更可靠。