Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM-Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.
Department of Psychology, Université de Montréal, Montreal, Quebec, Canada.
Sleep. 2021 Mar 12;44(3). doi: 10.1093/sleep/zsaa186.
Aging is associated with reduced slow wave (SW) density (number SW/min in nonrapid-eye movement sleep) and amplitude. It has been proposed that an age-related decrease in SW density may be due to a reduction in electroencephalogram (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 with younger adults. Specifically, the adapted SW amplitude criteria increased the probability of occurrence of low amplitude SW (<80 µV) for older men especially. Our results thereby confirm an age-related decline in SW generation rather than an artifact 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.
衰老与慢波（SW）密度（非快速眼动睡眠中 SW/分钟的数量）和振幅降低有关。有人提出，SW 密度的年龄相关性降低可能是由于脑电图（EEG）振幅降低，而不是 SW 产生能力下降所致。在这里，我们提出了一种数据驱动的方法，根据年龄和性别调整 SW 振幅标准。我们预测，经过调整的标准将减少 SW 密度和 SW 特征的年龄和性别差异，但不会消除这些差异。共有 284 名健康的年轻和老年成年人参加了一夜的睡眠 EEG 记录。我们使用信噪比方法在第一组年轻（n = 97）和年长（n = 110）个体中定义了年龄和性别调整的 SW 标准。然后，我们在一个独立的第二组（n = 77，38 名年轻成年人和 39 名年长成年人）中使用这些年龄和性别特异性标准来评估 SW 密度和 SW 特征上的年龄和性别差异。在调整 SW 振幅标准后，我们发现 SW 密度仍然存在与年龄相关的差异，而与性别相关的差异消失了。实际上，与年轻成年人相比，年长成年人产生的 SW 较少。具体来说，适应后的 SW 振幅标准增加了老年男性出现低振幅 SW（<80 µV）的可能性。因此，我们的结果证实了 SW 产生与年龄相关的下降，而不是检测振幅标准的人为因素。至于 SW 特征，年龄和性别调整的标准在两个独立的队列中都显示出可重复的效果，这表明 SW 的库存更加可靠。
