Sex-related differences in sleep slow wave activity in major depressive disorder: a high-density EEG investigation

Abstract

BackgroundSleep disturbance plays an important role in major depressive disorder (MDD). Prior investigations have demonstrated that slow wave activity (SWA) during sleep is altered in MDD; however, results have not been consistent across studies, which may be due in part to sex-related differences in SWA and/or limited spatial resolution of spectral analyses. This study sought to characterize SWA in MDD utilizing high-density electroencephalography (hdEEG) to examine the topography of SWA across the cortex in MDD, as well as sex-related variation in SWA topography in the disorder.MethodsAll-night recordings with 256 channel hdEEG were collected in 30 unipolar MDD subjects (19 women) and 30 age and sex-matched control subjects. Spectral analyses of SWA were performed to determine group differences. SWA was compared between MDD and controls, including analyses stratified by sex, using statistical non-parametric mapping to correct for multiple comparisons of topographic data.ResultsAs a group, MDD subjects demonstrated significant increases in all-night SWA primarily in bilateral prefrontal channels. When stratified by sex, MDD women demonstrated global increases in SWA relative to age-matched controls that were most consistent in bilateral prefrontal regions; however, MDD men showed no significant differences relative to age-matched controls. Further analyses demonstrated increased SWA in MDD women was most prominent in the first portion of the night.ConclusionsWomen, but not men with MDD demonstrate significant increases in SWA in multiple cortical areas relative to control subjects. Further research is warranted to investigate the role of SWA in MDD, and to clarify how increased SWA in women with MDD is related to the pathophysiology of the disorder.

Effects of partial sleep deprivation on slow waves during non-rapid eye movement sleep: A high density EEG investigation

“…Semi-automatic artifact rejection was applied to remove channels with interrupted contact with the scalp or high-frequency artifact. Spectral analysis of NREM sleep (all N2 and N3 epochs) from 1 to 30Hz was performed for each channel in 6-second epochs (Welch’s averaged modified periodogram with a Hamming window; frequency resolution 0.17Hz), which maintained temporal congruence between spectral analysis and 30-second staging epochs (Goldstein et al, 2012; Plante et al, 2012). Slow wave energy (SWE; integrated power 1–4.5Hz totaled over cumulative 6-second epochs of N2/N3 sleep) was the primary measure of spectral power utilized in this study, with other bands examined on an exploratory basis.…”

You'll feel better in the morning: slow wave activity and overnight mood regulation in interepisode bipolar disorder

“…SWA deficits can be more pronounced in prefrontal and frontal areas (Plante et al , 2012, Werth et al , 1997), thus future studies of sleep in BD would benefit from utilizing hdEEG to explore topographic hypotheses. Sex differences in SWA are sometimes observed in unipolar depression, with some reports observing greater SWA in females (e.g., Plante et al , 2012). While sex differences in SWA were not observed here, this may be due to the predominantly female sample and resulting lack of power to detect sex effects.…”

Effects of oral temazepam on slow waves during non-rapid eye movement sleep in healthy young adults: A high-density EEG investigation

“…Semi-automatic artifact rejection was conducted to remove channels with interrupted contact with the scalp or high-frequency artifact. Spectral analysis of NREM sleep (all N2 and N3 epochs) was performed for each channel 6-second epochs (Welch’s averaged modified periodogram with a Hamming window; frequency resolution 0.17Hz) to maintain congruence between spectral analysis and 30-second staging epochs (Goldstein et al, 2012; Plante et al, 2012). To verify that slow wave activity (power in the 1–4.5Hz band) declined across the night for both conditions, exponential decay functions were calculated using similar methods to prior investigations (Armitage et al, 2000; Dijk et al, 1990; Plante et al, 2012).…”

“…These waveforms are thought to play several roles in the central nervous system (CNS), including promotion of sleep maintenance, quality, and restoration (Dijk, 2009). Correspondingly, alterations in slow waves have been described across a range of disorders associated with reduced sleep quality including major depressive disorder, idiopathic hypersomnia, and obstructive sleep apnea syndrome (Borbely et al, 1984; Hoffmann et al, 2000; Jones et al, 2014; Plante et al, 2012; Sforza et al, 2000). Slow waves are homeostatically regulated such that their highest activity is during early sleep, with decreasing activity as the night progresses (Borbely, 1982).…”

“…Slow waves demonstrate a characteristic topography with increased activity in frontal derivations (Cajochen et al, 1999; Finelli et al, 2000; Tinguely et al, 2006; Werth et al, 1997). Because use of limited-EEG montages can fail to detect pertinent alterations in SWA between groups (Plante et al, 2012), this study sought to utilize high-density (hd) EEG to evaluate the topographic effects of temazepam, a non-selective benzodiazepine, on slow waves. Based on the previous literature, we hypothesized that administration of the drug would result in reductions in SWA in later sleep cycles, but not during the first part of the night, a reduction in amplitude and incidence of slow waves, and that both spectral and morphological changes would be more pronounced in frontal EEG derivations.…”