The sleep EEG spectrum is a sexually dimorphic marker of general intelligence

Abstract

The shape of the EEG spectrum in sleep relies on genetic and anatomical factors and forms an individual “EEG fingerprint”. Spectral components of EEG were shown to be connected to mental ability both in sleep and wakefulness. EEG sleep spindle correlates of intelligence, however, exhibit a sexual dimorphism, with a more pronounced association to intelligence in females than males. In a sample of 151 healthy individuals, we investigated how intelligence is related to spectral components of full-night sleep EEG, while controlling for the effects of age. A positive linear association between intelligence and REM anterior beta power was found in females but not males. Transient, spindle-like “REM beta tufts” are described in the EEG of healthy subjects, which may reflect the functioning of a recently described cingular-prefrontal emotion and motor regulation network. REM sleep frontal high delta power was a negative correlate of intelligence. NREM alpha and sigma spectral power correlations with intelligence did not unequivocally remain significant after multiple comparisons correction, but exhibited a similar sexual dimorphism. These results suggest that the neural oscillatory correlates of intelligence in sleep are sexually dimorphic, and they are not restricted to either sleep spindles or NREM sleep.

Brain age from the electroencephalogram of sleep

“…(2) underlying diagnosed or undiagnosed neurological or psychiatric diseases; (3) general medical health, including diabetes and small vessel cerebrovascular disease; (4) there are substantial genetically-determined stable inter-individual differences in the EEG; (5) exposure to environmental insults. Further studies are needed to clarify the relative contributions of the various types of neurophysiological factors, and to measure the association between EEG-based brain age and various outcomes, such as cognitive performance (Steffener et al, 2016), intelligence (Ujma et al, 2017) and survival . The deviations suggest that there are unobserved factors, such as diet, exercise and diseases, to further explain the variance.…”

A new set of composite, non-redundant electroencephalogram measures of non-rapid eye movement sleep based on the power law scaling of the Fourier spectrum

“…Intelligence was shown to correlate positively with NREM sleep EEG sleep spindle activity (Bódizs et al, 2005). Although, a recent metaanalysis casts doubt on the sexual dimorphism of this relationship (Ujma, 2018), the dataset we analyse in our current report is characterized by a clear difference among women and men: women were characterized by positive correlation between sleep spindle amplitude/power and IQ, whereas null correlations were reported for men (Ujma et al, 2014; Ujma et al, 2017). As our current analyses are based on the same dataset, we hypothesize (H6) that P Peak (f maxPeak ) values of the sleep spindle range (9–18 Hz) correlate positively with IQ in women, but not in men.…”

“…Here we reveal a positive correlation between whitened spectral peak amplitude of sleep spindle frequency activity during NREM sleep and IQ in women, but not in men (Table 4; Fig 3). Intelligence was shown to be reflected in the intensity (amplitude and/or density) of phasic sleep spindle events or alternatively in the spectral power of sleep spindle frequency activity during NREM sleep (Bódizs et al, 2005; Ujma et al, 2014, Ujma et al, 2017; Ujma, 2018). In the database we use in our present study a marked sexual dimorphism of this effect was also revealed: women but not men were shown to be characterized by the sleep spindle amplitude/power vs IQ correlations (Ujma et al, 2014; Ujma et al, 2017).…”

“…Intelligence was shown to be reflected in the intensity (amplitude and/or density) of phasic sleep spindle events or alternatively in the spectral power of sleep spindle frequency activity during NREM sleep (Bódizs et al, 2005; Ujma et al, 2014, Ujma et al, 2017; Ujma, 2018). In the database we use in our present study a marked sexual dimorphism of this effect was also revealed: women but not men were shown to be characterized by the sleep spindle amplitude/power vs IQ correlations (Ujma et al, 2014; Ujma et al, 2017). Although this latter effect was not unequivocally reflected in a significant meta-regression between effect size and % female in the sample in a subsequent metaanalysis, here we refer to it because convergent findings obtained by different methods used on the same dataset are an issue of validity of the methods.…”

“…The frequency characteristics of sleep-dependent neuronal oscillations as recorded by scalp electroencephalography (EEG) are increasingly recognized as potent markers of aging (Pótári et al, 2017; Ujma et al, 2019), health and disease (Kaskie and Ferrarelli, 2019), typical and atypical development and maturation (Campbell et al, 2012; Bódizs et al, 2012), as well as of neurocognitive features of high practical relevance (Bódizs et al, 2005; Ujma et al, 2017; Ujma, 2018). However, many of these studies are suffering from increased susceptibility to Type I error as a result of an inherently increased level of “researcher degrees of freedom”.…”