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See detailPositive Effect of Cognitive Reserve on Episodic Memory, Executive and Attentional Functions Taking Into Account Amyloid-Beta, Tau, and Apolipoprotein E Status
Narbutas, Justinas ULiege; Chylinski, Daphné ULiege; Van Egroo, Maxime et al

in Frontiers in Aging Neuroscience (2021)

Studies exploring the simultaneous influence of several physiological and environmental factors on domain-specific cognition in late middle-age remain scarce. Therefore, our objective was to determine the ... [more ▼]

Studies exploring the simultaneous influence of several physiological and environmental factors on domain-specific cognition in late middle-age remain scarce. Therefore, our objective was to determine the respective contribution of modifiable risk/protective factors (cognitive reserve and allostatic load) on specific cognitive domains (episodic memory, executive functions, and attention), taking into account non-modifiable factors [sex, age, and genetic risk for Alzheimer’s disease (AD)] and AD-related biomarker amount (amyloid-beta and tau/neuroinflammation) in a healthy late-middle-aged population. One hundred and one healthy participants (59.4 ± 5 years; 68 women) were evaluated for episodic memory, executive and attentional functioning via neuropsychological test battery. Cognitive reserve was determined by the National Adult Reading Test. The allostatic load consisted of measures of lipid metabolism and sympathetic nervous system functioning. The amyloid-beta level was assessed using positron emission tomography in all participants, whereas tau/neuroinflammation positron emission tomography scans and apolipoprotein E genotype were available for 58 participants. Higher cognitive reserve was the main correlate of better cognitive performance across all domains. Moreover, age was negatively associated with attentional functioning, whereas sex was a significant predictor for episodic memory, with women having better performance than men. Finally, our results did not show clear significant associations between performance over any cognitive domain and apolipoprotein E genotype and AD biomarkers. This suggests that domain-specific cognition in late healthy midlife is mainly determined by a combination of modifiable (cognitive reserve) and non-modifiable factors (sex and age) rather than by AD biomarkers and genetic risk for AD. [less ▲]

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See detailL'impact du confinement dû à la pandémie de COVID-19 sur la fatigue
Requier, Florence ULiege; Guillemin, Camille ULiege; Reyt, Mathilde ULiege et al

Conference (2021, May 10)

La pandémie de COVID-19 et le confinement instauré en mars 2020 ont eu des répercussions sur notre fonctionnement quotidien et notre qualité de vie. Certaines études se sont intéressées à leurs impacts ... [more ▼]

La pandémie de COVID-19 et le confinement instauré en mars 2020 ont eu des répercussions sur notre fonctionnement quotidien et notre qualité de vie. Certaines études se sont intéressées à leurs impacts sur des variables plutôt affectives, cependant, l'impact de ces événements sur la fatigue mentale et physique de la population a été peu étudié. L’objectif de notre étude est de déterminer quels facteurs, liés à la nouvelle situation, ont influencé la fatigue, d’une part, chez les travailleurs et, d’autre part, chez les personnes retraitées. Un questionnaire en ligne a été développé et diffusé pendant le confinement auprès d’une population européenne francophone. Des modèles généralisés mixtes ont été utilisés, séparément, sur les données de 430 travailleurs (Âge : 40.43 ± 12.16, 357 femmes) et de 124 personnes retraitées (Âge : 68.86 ± 6.13, 66 femmes). Nous avons constaté une augmentation de la fatigue physique et de la fatigue mentale perçues et nous avons observé si cette augmentation était liée à certaines variables telles que les données démographiques et affectives, l’évolution de l’environnement professionnel, l’évolution des occupations quotidiennes, les préoccupations liées au COVID, les changements relatifs au sommeil et l’évolution du degré de charge mentale (p<.05). Chez les travailleurs, nous avons trouvé des associations positives entre la fatigue physique et l’anxiété, l’effort au travail, les préoccupations liées au COVID, le dysfonctionnement diurne et la charge mentale. La fatigue physique a des relations négatives avec l’âge, les activités physiques, le degré de satisfaction envers les occupations, ainsi que la qualité et l’efficacité de sommeil. La fatigue mentale est, quant à elle, associée positivement avec l’anxiété, l’effort au travail, le télétravail, les préoccupations liées au COVID, les troubles du sommeil, le dysfonctionnement diurne et la charge mentale. Des relations négatives sont mises en évidence concernant la fatigue mentale et l’occupation au travail, l’utilisation de somnifères et le degré de satisfaction envers les occupations. Chez les personnes retraitées, nous avons observé des relations positives entre la fatigue physique et le niveau d’anxiété ainsi que les préoccupations liées au COVID-19 et une relation négative avec le degré de satisfaction envers les occupations L’augmentation de fatigue est associée à la modification d’une série d’activités quotidiennes induite par la situation sanitaire. Des programmes d’action ciblés sur ces comportements ou ces états modifiables laissent entrevoir des pistes d’intervention adaptées à cette situation. L’impact à long terme et les éventuelles stratégies mises en place par la population, suite à cette situation, restent à être investigués. [less ▲]

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See detailENIGMA-Sleep: Challenges, opportunities, and the road map
Tahmasian, Masoud; Aleman, André; Andreassen, Ole A. et al

in Journal of Sleep Research (2021), e13347

Neuroimaging and genetics studies have advanced our understanding of the neurobiology of sleep and its disorders. However, individual studies usually have limitations to identifying consistent and ... [more ▼]

Neuroimaging and genetics studies have advanced our understanding of the neurobiology of sleep and its disorders. However, individual studies usually have limitations to identifying consistent and reproducible effects, including modest sample sizes, heterogeneous clinical characteristics and varied methodologies. These issues call for a large-scale multi-centre effort in sleep research, in order to increase the number of samples, and harmonize the methods of data collection, preprocessing and analysis using pre-registered well-established protocols. The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium provides a powerful collaborative framework for combining datasets across individual sites. Recently, we have launched the ENIGMA-Sleep working group with the collaboration of several institutes from 15 countries to perform large-scale worldwide neuroimaging and genetics studies for better understanding the neurobiology of impaired sleep quality in population-based healthy individuals, the neural consequences of sleep deprivation, pathophysiology of sleep disorders, as well as neural correlates of sleep disturbances across various neuropsychiatric disorders. In this introductory review, we describe the details of our currently available datasets and our ongoing projects in the ENIGMA-Sleep group, and discuss both the potential challenges and opportunities of a collaborative initiative in sleep medicine. [less ▲]

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See detailAssociations between cognitive complaints, memory performance, mood and amyloid-β accumulation in healthy amyloid negative late-midlife individuals
Narbutas, Justinas ULiege; Van Egroo, Maxime; Chylinski, Daphné ULiege et al

in Journal of Alzheimer's Disease (2021), 83

Background. Cognitive complaints are gaining more attention as they may represent an early marker of increased risk for AD in individuals without objective decline at standard neuropsychological ... [more ▼]

Background. Cognitive complaints are gaining more attention as they may represent an early marker of increased risk for AD in individuals without objective decline at standard neuropsychological examination. Objective. Our aim was to assess whether cognitive complaints in late middle-aged individuals not seeking medical help are related to objective cognitive outcomes known as early markers for AD risk, concomitant affective state, and amyloid-β (Aβ) burden. Methods. Eighty-seven community-based cognitively normal individuals aged 50-69 years underwent neuropsychological assessment for global cognition, using Preclinical Alzheimer’s Cognitive Composite 5 (PACC5) score, and a more specific episodic memory measure. Affective state was based on self-assessment questionnaires for depression and anxiety. Aβ PET burden was assessed via [18F]Flutemetamol (N=84) and [18F]Florbetapir (N=3) uptake. Cognitive complaints were evaluated using Cognitive Difficulties Scale. Results. Higher cognitive complaints were significantly associated with lower episodic memory performance and worse affective state. Moreover, higher level of cognitive complaints was related to higher (but still sub-clinical) global Aβ accumulation (at uncorrected significance level). Importantly, all three aspects remained significant when taken together in the same statistical model, indicating that they explained distinct parts of variance. Conclusion. In healthy Aβ negative late middle-aged individuals, a higher degree of cognitive complaints is associated with lower episodic memory efficiency, more anxiety and depression, as well as, potentially, with higher Aβ burden, suggesting that complaints might signal subtle decline. Future studies should untangle how cognitive complaints in healthy aging populations are related to longitudinal changes in objective cognition and AD biomarker correlates. [less ▲]

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See detailChanges in sleep timing and subjective sleep quality during the COVID-19 lockdown in Italy and Belgium: age, gender and working status as modulating factors
Cellini, Nicola; Conte, Francesca; De Rosa, Oreste et al

in Sleep Medicine (2021)

Italy and Belgium have been among the first western countries to face the Coronavirus disease 2019 (COVID-19) emergency, imposing a total lockdown over the entire national territories. These limitations ... [more ▼]

Italy and Belgium have been among the first western countries to face the Coronavirus disease 2019 (COVID-19) emergency, imposing a total lockdown over the entire national territories. These limitations have proven effective in slowing down the spread of the infection. However, the benefits obtained in public health have come with huge costs in terms of social, economic, and psychological well-being. In the current study, we aimed at investigating how the period of home confinement affected self-reported sleep characteristics in Italians and Belgians, with special regard to sleep timing and subjective quality. Using an online survey we collected data from 2272 participants, 1622 Italians (Mage=34.1±13.6 years, 1171 F), and 650 Belgian (Mage=43.0±16.8 years, 509 F). Participants reported their sleep pattern (e.g., bedtime, risetime) and perceived sleep quality during and, retrospectively, before the lockdown. During the lockdown, sleep timing was significantly delayed, time spent in bed increased, and sleep quality was markedly impaired in both Italians and Belgians. The most vulnerable individuals appeared to be women, subjects experiencing a more negative mood, and those perceiving the pandemic situation as highly stressful. However, the two samples differed in the subgroups most affected by the changes, possibly because of the different welfare systems of the two countries. In fact, in the Italian sample sleep quality and timing underwent significant modifications especially in unemployed participants, whereas in the Belgian sample this category was the one who suffered less from the restrictions. Considering that the novel coronavirus has spread across the whole globe, involving countries with different types of health and welfare systems, understanding which policy measures have the most effective protecting role on physical and mental health is of primary importance. [less ▲]

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See detailEarly brainstem [18F]THK5351 uptake is linked to cortical hyper-excitability in healthy aging
Van Egroo, Maxime ULiege; Chylinski, Daphné ULiege; Narbutas, Justinas ULiege et al

in JCI Insight (2020), Online ahead of print

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See detailContributions of sleep to daytime functioning, well-beingand cognitive fatigue
Schmidt, Christina ULiege; Collette, Fabienne ULiege

Conference (2020, September 23)

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See detailAssociation between sleep regulation and neuroimaging-derived myelin markers
Deantoni, Michele ULiege; Muto, Vincenzo ULiege; Hammad, Grégory ULiege et al

Conference (2020, September 22)

Introduction Sleep plays a crucial role in brain plasticity, and has been suggested to be involved in myelin organization. Here we assessed the association between sleep homeostatic responses and ... [more ▼]

Introduction Sleep plays a crucial role in brain plasticity, and has been suggested to be involved in myelin organization. Here we assessed the association between sleep homeostatic responses and quantitative MRI-derived myelin content in a sample of healthy young men. Methods: 238 male participants (age: 22.12.7) underwent an in-lab protocol to assess homeostatic responses in slow wave and REM sleep through a modulation of prior wakefulness and sleep duration. The protocol encompassed four conditions: a baseline night (BAS, duration adjusted on participant’s sleep-wake schedule), a 12h sleep extension night (EXT) followed by a 4-h nap and an 8-h sleep opportunity night (sleep saturation; SAT) and a 12h recovery night (REC) following 40-hours sleep deprivation. For each night, four sleep parameters were extracted: sleep slow wave activity at the beginning of the night (SWA0), its overnight exponential dissipation rate (tau), and overnight mean theta and beta power per REM epoch. Participants underwent a multiparameter brain MRI protocol at 3T to extract quantitative maps sensitive to different myelin biomarkers. F-contrasts were calculated to assess whether the modularity of sleep parameters across sleep conditions explains variance in myelin biomarkers. Reported statistics are family-wise-error corrected over the entire brain volume (pFWE <.05). Results: Slow wave sleep duration and SWA0 were modulated across all sleep conditions (REC>BAS>EXT>SAT; all p < 0.001), while REM sleep percentage significantly differed only between SAT and the other sleep contexts (F(3,1257)= 13.676743, p<.001). The modulation of NREM SWA0 was associated with myelin content in the medio-temporal lobe, encompassing the bilateral hippocampus and entorhinal cortex (grey and white matter), while the modulation of REM beta power was associated to myelin content in diffuse thalamocortical tracts and overhead cortices. Discussion: Spectral power in sleep-specific frequency bands across sleep homeostasis contexts is associated with myelin content in the hippocampus and surrounding cortices as well as thalamocortical fibers. The hippocampus has been proposed as a key player for temporal coupling of brain oscillations, while thalamocortical fibers myelination may facilitate the cortical response to sleep-dependent diencephalic activity. As myelin stands for conduction velocity, it could facilitate the modulation of brain electrical oscillations, and putatively also the homeostatic response of sleep. [less ▲]

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See detailArousals during sleep are associated with cortical amyloid-β burden and cognition in healthy older adults
Chylinski, Daphné ULiege; Van Egroo, Maxime ULiege; Narbutas, Justinas ULiege et al

Conference (2020, September 22)

Arousals during sleep have been studied in sleep pathologies such as sleep apnoea and periodic limb movement disorder, or in interventional experimental protocols triggering arousals through external ... [more ▼]

Arousals during sleep have been studied in sleep pathologies such as sleep apnoea and periodic limb movement disorder, or in interventional experimental protocols triggering arousals through external stimulations (mainly noise). Those studies generally pointed towards a detrimental role of arousals. Yet, the causes and consequences of spontaneous arousals in healthy individuals remain largely unknown. Recently, a bidirectional detrimental link between sleep-wake dysfunction and the pathogenesis of Alzheimer’s disease is emerging in the literature, including the abnormal accumulation of amyloid-β (Aβ) and tau protein in the brain. Here, we investigated whether spontaneous arousals during sleep were associated with Aβ and tau burden, as well as with cognitive performance. We recorded night-time sleep of 101 cognitively normal older individuals devoid of sleep disorders (aged 51-69; mean 59 ± 5; 68 females) under EEG. We assessed 18F-flutemetamol and 18F-THK 5351 regional brain uptake using Positron Emission Tomography to infer their level of Aβ and tau protein burden, respectively. Validated automatic arousal detection was computed on all EEG recordings. All participants completed an extensive cognitive battery of neuropsychological tasks to assess memory, attentional, and executive functioning while well-rested. Generalised linear mixed models analyses revealed that arousals concomitant to a muscular tone increase (arousals EMG) are significantly negatively associated with Aβ burden in the cortex (F(1,95) = 11.62, p = .001), while correcting for age, sex and total sleep time, whereas no such relationship was observed for tau (p = .47). Furthermore, global cognitive performances were positively linked with arousals EMG throughout the night (F(1,95) = 6.38, p = .01), the observed relationship being mainly driven by performances in the attentional (p = .005) and executive domain (p = .04), after adjusting for age, sex, education and total sleep time. These findings suggest arousals during sleep may form a heterogeneous category of events composed of arousals evoked by external or pathological event, that may be deleterious, and spontaneous arousals that may be associated with better brain structure or cognition. Future research should try to further characterise arousal events to disentangle what has been so far taring everyone with the same brush. [less ▲]

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See detailVariability of visual and automated sleep stage scoring in the elderly
Chylinski, Daphné ULiege; Berthomier, Christian; Lambot, Eric ULiege et al

Poster (2020, September 22)

Visual scoring of sleep recordings is characterized by inter-scorer variability. This methodological issue can be amplified in older individual recordings because sleep changes markedly in aging. Here, we ... [more ▼]

Visual scoring of sleep recordings is characterized by inter-scorer variability. This methodological issue can be amplified in older individual recordings because sleep changes markedly in aging. Here, we aimed to investigate sleep scoring variability in aged participants through a visual-automatic sleep scoring comparison. Sleep recordings of 20 subjects (10 women, 61±5 years) were included. Automatic sleep scoring (AS) was performed by Aseega algorithm, previously validated on young healthy participants. Visual scoring (VS) was performed by two experts (VS1, VS2) from different centers according to AASM rules. Epoch-by-epoch agreements (concordance and Conger’s kappa coefficient, ) were computed. Generalized linear mixed models assessed potential scorer effects on sleep parameters (time spent in N1/N2/N3/REM, tN1/tN2/tN3/tREM; wake after sleep onset, WASO; total sleep time, TST; sleep efficiency, SE). Overall agreement between the 3 scorings was  = 0.60 (moderate). Pairwise agreements were as follows: VS1 vs. VS2, 76% (=0.67); AS vs. VS1, 67% (0.54), AS vs. VS2, 74% (0.60). Agreement between AS and consensual VS was 78% (0.60). GLMMs showed disparate pairs of agreeing scorers depending on the sleep parameter considered. For tN1, AS showed differences with both VS (p < .0001) who did not differ between themselves. Differences were found between both VS for tN2 and tN3 (p < .0001) and WASO (p = .006), while AS showed no significant difference with VS2. All three scorers differed for TST (p = .05) and SE (p = .04). No differences across scorers were found for tREM. Agreement between scorers, whether between VS or AS and VS proved lower than what is usually reported in the literature for the general population. This is likely due to the fact that with ageing, sleep undergoes a series of changes with, at the macrostructural level, lower sleep stability and, at the microstructural level, lower EEG voltage dynamics. This certainly renders sleep more difficult to score, which might lead to increased inter-rater variability and rises methodological questions relative to sleep scoring in the aged population. [less ▲]

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See detailSleep slow waves generation and medial prefrontal microstructure in healthy older individuals
Van Egroo, Maxime ULiege; Chylinski, Daphné ULiege; Narbutas, Justinas ULiege et al

Conference (2020, September 22)

Introduction. Aging is associated with alterations in sleep-wake regulation that have been associated with changes in brain structural integrity. In particular, the ability to generate slow oscillations ... [more ▼]

Introduction. Aging is associated with alterations in sleep-wake regulation that have been associated with changes in brain structural integrity. In particular, the ability to generate slow oscillations during non-rapid eye movement (NREM) sleep decreases as early as in the 5th decade of life, predominantly over frontal regions. While previous investigations have identified macrostructural brain correlates of the age-related decrement in sleep slow waves generation, their relationships with brain tissue microstructure remain poorly understood. Methods. We recorded sleep under electroencephalography in 99 healthy older individuals (mean age = 59.6 ± 5.2 years; 66 women), and we quantified slow waves generation using the overnight cumulated power density in the delta band (0.5-4 Hz) during NREM sleep over the frontal Fz derivation. All participants also underwent 3T magnetic resonance imaging (MRI) scans to investigate tissue myelin content based on quantitative magnetization transfer (MT) saturation mapping, as well as diffusion-based metrics derived from neurite orientation dispersion and density imaging (NODDI) model. A region of interest covering bilateral medial prefrontal cortices was used to extract regional grey matter values. Results. We first observed that MT signal in the medial prefrontal cortex was positively associated with higher neurite orientation dispersion (r = .30, p = .003) and density (r = .22, p = .03), supposedly reflecting preserved microstructural integrity. Crucially, overnight NREM sleep slow waves generation was significantly related to higher prefrontal MT signal (r = .22, p = .03), but not to NODDI metrics (dispersion: r = .02, p = .85; density: r = .09, p = .36). Generalized linear mixed models adjusted for demographics and total sleep time confirmed these relationships, although as a statistical trend for MT signal (F1,93 = 3.64, p = .06). Discussion. Our findings suggest a positive association between tissue myelin content within medial prefrontal grey matter and generation of slow waves during NREM sleep in aging. Preserved prefrontal myelination may facilitate neuronal synchronization through enhanced cortico-cortical connections, resulting in higher power density in the slower frequency band. Given the existing link between sleep characteristics and age-related cognitive decline, these results may have implications for successful cognitive aging. Support: FNRS, ULiège, ARC17/21-09, FEDER, WBI, Clerdent Foundation, Leon Frédéricq Foundation [less ▲]

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See detailpyActigraphy, an open-source python package for actigraphy data visualisation and analysis
Hammad, Grégory ULiege; Reyt, Mathilde ULiege; Beliy, Nikita ULiege et al

Poster (2020, September)

The pyActigraphy toolbox, an open-source python package for actigraphy data visualisation and analysis, offers functionalities to automatise data pre-processing, read large file batches and implement ... [more ▼]

The pyActigraphy toolbox, an open-source python package for actigraphy data visualisation and analysis, offers functionalities to automatise data pre-processing, read large file batches and implement various metrics and techniques for actigraphy data analysis. By developing the pyActigraphy package, we not only hope to facilitate data analysis but also foster research using actimetry and drive a community effort to improve this open-source package and develop new variables and algorithms. [less ▲]

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See detailFractal regulation of human motor activity and its manifestation at circadian and ultradian time scales
Hammad, Grégory ULiege; Reyt, Mathilde ULiege; Baillet, Marion ULiege et al

Poster (2020, September)

Human activity exhibits a fractal behaviour, characterised by scale-invariant patterns over time scales ranging from minutes to 24 hours. This suggests the existence of a control mechanism with feedback ... [more ▼]

Human activity exhibits a fractal behaviour, characterised by scale-invariant patterns over time scales ranging from minutes to 24 hours. This suggests the existence of a control mechanism with feedback interactions. Aging and Alzheimer’s disease, both marked by an alteration of the suprachiasmatic nucleus (SCN), the circadian pacemaker, have been associated with a reduced scale-invariant correlation. However, the impact of this reduction on ultradian or circadian activity dynamics and its comparison with in-lab circadian measures, remains unclear. Our results link fractal indices, measured with actigraphy, to in-lab circadian markers. Interestingly, fractal scaling in the circadian regime is associated with both daytime rest, interpreted as a fragmentation of sustained daytime activity, and shorter ultradian daytime activity fragmentation. These results also highlight the link between LIDS oscillations at night and scale-invariance at ultradian time scales. Overall, our analysis suggests that previously reported indices of activity dynamics occurring at various time scales might be associated with a common underlying regulation mechanism, involving the SCN. [less ▲]

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See detailIt's about time: resting during daytime alters attention in the aged
Reyt, Mathilde ULiege; Deantoni, Michele ULiege; Lesoinne, Alexia ULiege et al

Poster (2020, September)

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