Habitual sleep durations and subjective sleep quality predict white matter differences in the human brain

Chronotype and subjective sleep quality predict white matter integrity in young people with emerging mental disorders

Protecting brain health is a goal of early intervention. We explored whether sleep quality or chronotype could predict white matter (WM) integrity in emerging mental disorders. Young people (N = 364) accessing early-intervention clinics underwent assessments for chronotype, subjective sleep quality, and diffusion tensor imaging. Using machine learning, we examined whether chronotype or sleep quality (alongside diagnostic and demographic factors) could predict four measures of WM integrity: fractional anisotropy (FA), and radial, axial, and mean diffusivities (RD, AD and MD). We prioritised tracts that showed a univariate association with sleep quality or chronotype and considered predictors identified by ≥80% of machine learning (ML) models as 'important'. The most important predictors of WM integrity were demographics (age, sex and education) and diagnosis (depressive and bipolar disorders). Subjective sleep quality only predicted FA in the perihippocampal cingulum tract, whereas chronotype had limited predictive importance for WM integrity. To further examine links with mood disorders, we conducted a subgroup analysis. In youth with depressive and bipolar disorders, chronotype emerged as an important (often top-ranking) feature, predicting FA in the cingulum (cingulate gyrus), AD in the anterior corona radiata and genu of the corpus callosum, and RD in the corona radiata, anterior corona radiata, and genu of corpus callosum. Subjective quality was not important in this subgroup analysis. In summary, chronotype predicted altered WM integrity in the corona radiata and corpus callosum, whereas subjective sleep quality had a less significant role, suggesting that circadian factors may play a more prominent role in WM integrity in emerging mood disorders.

Neuroscience meets behavior: A systematic literature review on magnetic resonance imaging of the brain combined with real-world digital phenotyping

A primary goal of neuroscience is to understand the relationship between the brain and behavior. While magnetic resonance imaging (MRI) examines brain structure and function under controlled conditions, digital phenotyping via portable automatic devices (PAD) quantifies behavior in real-world settings. Combining these two technologies may bridge the gap between brain imaging, physiology, and real-time behavior, enhancing the generalizability of laboratory and clinical findings. However, the use of MRI and data from PADs outside the MRI scanner remains underexplored. Herein, we present a Preferred Reporting Items for Systematic Reviews and Meta-Analysis systematic literature review that identifies and analyzes the current state of research on the integration of brain MRI and PADs. PubMed and Scopus were automatically searched using keywords covering various MRI techniques and PADs. Abstracts were screened to only include articles that collected MRI brain data and PAD data outside the laboratory environment. Full-text screening was then conducted to ensure included articles combined quantitative data from MRI with data from PADs, yielding 94 selected papers for a total of N = 14,778 subjects. Results were reported as cross-frequency tables between brain imaging and behavior sampling methods and patterns were identified through network analysis. Furthermore, brain maps reported in the studies were synthesized according to the measurement modalities that were used. Results demonstrate the feasibility of integrating MRI and PADs across various study designs, patient and control populations, and age groups. The majority of published literature combines functional, T1-weighted, and diffusion weighted MRI with physical activity sensors, ecological momentary assessment via PADs, and sleep. The literature further highlights specific brain regions frequently correlated with distinct MRI-PAD combinations. These combinations enable in-depth studies on how physiology, brain function and behavior influence each other. Our review highlights the potential for constructing brain-behavior models that extend beyond the scanner and into real-world contexts.

Sleep quality and executive function in a diverse sample of healthy young adults

Few studies examine the relationship between sleep and executive function in diverse samples of young adults. Our research aims to fill this gap by analyzing how self-reported sleep quality is related to informant-rated executive function as a whole and its working memory component in a diverse sample of 29 healthy college students. Using the self-report measure, the Pittsburgh Sleep Quality Index (PSQI), we divided our sample into two groups based on cutoff criteria (score ≥5: poor sleep): good sleep quality (n = 11) and poor sleep quality (n = 18). Participants were on average 20.86 years old. Informants rated participants' executive functioning and working memory using the Frontal Systems Behavior Scale (FrSBe) and Behavior Rating Inventory of Executive Function (BRIEF). Individuals in the poor sleep quality group were reported as having significantly worse executive function and working memory scores. Young adult college students who report less than 7 hours of sleep per night have lower scores on informant measures of working memory and executive function. This study raises awareness about how self-reported sleep experiences are related to other's observation of cognitive abilities in everyday life in a diverse young adult sample.

Sleep Duration and Executive Function in Adults

PURPOSE OF REVIEW

To review the literature examining the relationship between sleep and cognition, specifically examining the sub-domain of executive function. We explore the impact of sleep deprivation and the important question of how much sleep is required for optimal cognitive performance. We consider how other sleep metrics, such as sleep quality, may be a more meaningful measure of sleep. We then discuss the putative mechanisms between sleep and cognition followed by their contribution to developing dementia.

RECENT FINDINGS

Sleep duration and executive function display a quadratic relationship. This suggests an optimal amount of sleep is required for daily cognitive processes. Poor sleep efficiency and sleep fragmentation are linked with poorer executive function and increased risk of dementia during follow-up. Sleep quality may therefore be more important than absolute duration. Biological mechanisms which may underpin the relationship between sleep and cognition include brain structural and functional changes as well as disruption of the glymphatic system. Sleep is an important modifiable lifestyle factor to improve daily cognition and, possibly, reduce the risk of developing dementia. The impact of optimal sleep duration and sleep quality may have important implications for every ageing individual.

Disrupted white matter integrity in primary insomnia and major depressive disorder: relationships to sleep quality and depression severity

This study examined the integrity of white matter tracts in 25 participants with primary insomnia (PI), 50 participants with major depressive disorder (MDD), and 25 healthy controls. Seven white matter tracts, selected based on prior research, were quantified by fractional anisotropy (FA) as well as by related measures of diffusivity using diffusion tensor imaging (DTI) on a 3-T scanner. All 100 participants were free of significant medical, psychiatric (excluding the MDD group) and sleep disorders (excluding the PI group), were free of central nervous system medications, and completed an extensive clinical assessment. Subjective and objective sleep measures revealed significant sleep disruption in both the PI and MDD groups. Relative to the controls, both the PI and MDD groups demonstrated impaired integrity in three of the seven white matter tracts: the genu of the corpus callosum (GenuCC), the superior longitudinal fasciculus (SLF), and the inferior longitudinal fasciculus (ILF). We demonstrated reduced FA in the GenuCC, reduced FA and reduced axial diffusivity (AD) in the SLF, as well as reduced AD and radial diffusivity in the ILF. Finally, in an exploratory analysis of the combined cohorts, FA in the GenuCC and FA in the SLF were negatively correlated with depression severity and positively correlated with total sleep time. Abnormalities documented in the GenuCC, SLF and ILF, and present in both the PI and MDD groups may suggest some shared neurobiology.

Association of Sociodemographic Factors with Physical Activity and Sleep Quality in Arab and Non-Arab Individuals of Both Sexes during the COVID-19 Pandemic

We explored the association of sociodemographic and anthropometric factors with self-reported physical activity (PA) and sleep quality in Arab and non-Arab individuals of both sexes during the COVID-19 pandemic. In this cross-sectional study, 638 participants (those recovered from COVID-19 = 149, and non-infected = 489) of both sexes aged 18-55 years were recruited. Their sociodemographic and anthropometric information, PA (self-reported using the International Physical Activity Questionnaire Short-form [IPAQ-SF)]) and sleep quality (self-reported using the Pittsburgh Sleep Quality Index [PSQI]) were documented. The association between participants' characteristics, PA levels, and sleep quality were determined using the chi-squared test. Variables significantly associated with IPAQ and PSQI in bivariate analyses were included in a multivariate binary logistic regression model. Men were more active than women (odds ratio [OR] = 1.66, p = 0.010), and non-Arab participants were more active than Arab ones (OR = 1.49, p = 0.037). Participants ≥40 years, men, non-Arab participants, and those who were working were more likely to have a good sleep quality than those ≤40 years (OR 1.70, p = 0.048), women (OR 1.10, p = 0.725), Arab individuals (OR 1.95, p = 0.002), and unemployed people (OR 2.76, p = 0.007). Male and non-Arab participants seemed to have a better self-reported PA and sleep quality compared to female and Arab participants, during the pandemic.

The role of brain white matter in depression resilience and response to sleep interventions

Insomnia poses a high risk for depression. Brain mechanisms of sleep and mood improvement following cognitive behavioural therapy for insomnia remain elusive. This longitudinal study evaluated whether (i) individual differences in baseline brain white matter microstructure predict improvements and (ii) intervention affects brain white matter microstructure. People meeting the Diagnostic and Statistical Manual of Mental Disorders-5 criteria for Insomnia Disorder (n = 117) participated in a randomized controlled trial comparing 6 weeks of no treatment with therapist-guided digital cognitive behavioural therapy for insomnia, circadian rhythm support or their combination (cognitive behavioural therapy for insomnia + circadian rhythm support). Insomnia Severity Index and Inventory of Depressive Symptomatology-Self Report were assessed at baseline and followed up at Weeks 7, 26, 39 and 52. Diffusion-weighted magnetic resonance images were acquired at baseline and Week 7. Skeletonized white matter tracts, fractional anisotropy and mean diffusivity were quantified both tract-wise and voxel-wise using tract-based spatial statistics. Analyses used linear and mixed effect models while correcting for multiple testing using false discovery rate and Bonferroni for correlated endpoint measures. Our results show the following: (i) tract-wise lower fractional anisotropy in the left retrolenticular part of the internal capsule at baseline predicted both worse progression of depressive symptoms in untreated participants and more improvement in treated participants (fractional anisotropy × any intervention, PFDR = 0.053, Pcorr = 0.045). (ii) Only the cognitive behavioural therapy for insomnia + circadian rhythm support intervention induced a trend-level mean diffusivity decrease in the right superior corona radiata (PFDR = 0.128, Pcorr = 0.108), and individuals with a stronger mean diffusivity decrease showed a stronger alleviation of insomnia (R = 0.20, P = 0.035). In summary, individual differences in risk and treatment-supported resilience of depression involve white matter microstructure. Future studies could target the role of the left retrolenticular part of the internal capsule and right superior corona radiata and the brain areas they connect.

Relationships Among Short Self-Reported Sleep Duration, Cognitive Impairment, and Insular Functional Connectivity in Late-Life Depression

BACKGROUND

Both late-life depression (LLD) and short sleep duration increase the risk of cognitive impairment. Increased insular resting-state functional connectivity (FC) has been reported in individuals with short sleep duration and dementia.

OBJECTIVE

This study aimed to investigate whether short sleep duration is associated with impaired cognition and higher insular FC in patients with LLD.

METHODS

This case- control study recruited 186 patients with LLD and 83 normal controls (NC), and comprehensive psychometric assessments, sleep duration reports and resting-state functional MRI scans (81 LLD patients and 54 NC) were conducted.

RESULTS

Patients with LLD and short sleep duration (LLD-SS patients) exhibited more severe depressive symptoms and worse cognitive function than those with normal sleep duration (LLD-NS patients) and NC. LLD-SS patients exhibited higher FC between the bilateral insula and inferior frontal gyrus (IFG) pars triangularis than LLD-NS patients and NC, while LLD-NS patients exhibited lower FC than NC. Increased insular FC was correlated with short sleep duration, severe depressive symptoms, and slower information processing speeds. Furthermore, an additive effect was found between sleep duration and LLD on global cognition and insular FC.

CONCLUSION

LLD-SS patients exhibited impaired cognition and increased insular FC. Abnormal FC in LLD-SS patients may be a therapeutic target for neuromodulation to improve sleep and cognitive performance and thus decrease the risk of dementia.

Sleep Quality Disturbances Are Associated with White Matter Alterations in Veterans with Post-Traumatic Stress Disorder and Mild Traumatic Brain Injury

Sleep disturbances are strongly associated with mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD). PTSD and mTBI have been linked to alterations in white matter (WM) microstructure, but whether poor sleep quality has a compounding effect on WM remains largely unknown. We evaluated sleep and diffusion magnetic resonance imaging (dMRI) data from 180 male post-9/11 veterans diagnosed with (1) PTSD (n = 38), (2) mTBI (n = 25), (3) comorbid PTSD+mTBI (n = 94), and (4) a control group with neither PTSD nor mTBI (n = 23). We compared sleep quality (Pittsburgh Sleep Quality Index, PSQI) between groups using ANCOVAs and calculated regression and mediation models to assess associations between PTSD, mTBI, sleep quality, and WM. Veterans with PTSD and comorbid PTSD+mTBI reported poorer sleep quality than those with mTBI or no history of PTSD or mTBI (p = 0.012 to <0.001). Poor sleep quality was associated with abnormal WM microstructure in veterans with comorbid PTSD+mTBI (p < 0.001). Most importantly, poor sleep quality fully mediated the association between greater PTSD symptom severity and impaired WM microstructure (p < 0.001). Our findings highlight the significant impact of sleep disturbances on brain health in veterans with PTSD+mTBI, calling for sleep-targeted interventions.

Association between sleep slow-wave activity and in-vivo estimates of myelin in healthy young men

Sleep has been suggested to contribute to myelinogenesis and associated structural changes in the brain. As a principal hallmark of sleep, slow-wave activity (SWA) is homeostatically regulated but also differs between individuals. Besides its homeostatic function, SWA topography is suggested to reflect processes of brain maturation. Here, we assessed whether interindividual differences in sleep SWA and its homeostatic response to sleep manipulations are associated with in-vivo myelin estimates in a sample of healthy young men. Two hundred twenty-six participants (18-31 y.) underwent an in-lab protocol in which SWA was assessed at baseline (BAS), after sleep deprivation (high homeostatic sleep pressure, HSP) and after sleep saturation (low homeostatic sleep pressure, LSP). Early-night frontal SWA, the frontal-occipital SWA ratio, as well as the overnight exponential SWA decay were computed over sleep conditions. Semi-quantitative magnetization transfer saturation maps (MTsat), providing markers for myelin content, were acquired during a separate laboratory visit. Early-night frontal SWA was negatively associated with regionally decreased myelin estimates in the temporal portion of the inferior longitudinal fasciculus. By contrast, neither the responsiveness of SWA to sleep saturation or deprivation, its overnight dynamics, nor the frontal/occipital SWA ratio were associated with brain structural indices. Our results indicate that frontal SWA generation tracks inter-individual differences in continued structural brain re-organization during early adulthood. This stage of life is not only characterized by ongoing region-specific changes in myelin content, but also by a sharp decrease and a shift towards frontal predominance in SWA generation.

Frontal white matter association with sleep quality and the role of stress

An important measure of brain health is the integrity of white matter connectivity structures that link brain regions. Studies have found an association between poorer sleep quality and decreased white matter integrity. Stress is among the strongest predictors of sleep quality. This study aimed to evaluate the association between sleep quality and white matter and to test if the relationship persisted after accounting for stress. White matter microstructures were measured by diffusion tensor imaging in a population of Old Order Amish/Mennonite (N = 240). Sleep quality was determined by the Pittsburgh Sleep Quality Index. Current stress levels were measured by the perceived stress scale. Exposure to lifetime stress was measured by the lifetime stressor inventory. Microstructures of four white matter tracts: left and right anterior limbs of internal capsule, left anterior corona radiata, and genu of corpus callosum were significantly correlated with sleep quality (all p ≤ 0.001). The current stress level was a significant predictor of sleep quality (p ≤ 0.001) while lifetime stress was not. PSQI remained significantly associated with white matter integrity in these frontal tracts (all p < 0.01) after accounting for current stress and lifetime stress, while current and lifetime stress were not significant predictors of white matter in any of the four models. Sleep quality did not have any substantial mediation role between stress and white matter integrity. Sleep quality was significantly associated with several frontal white matter tracts that connect brain structures important for sleep regulation regardless of current or past stress levels.

Sleep Quality and Cognitive Decline Across the Adult Age Range: Findings from the Maastricht Aging Study (MAAS)

BACKGROUND

Sleep disturbances have been linked with cognitive decline and a higher risk of dementia. However, there is a lack of studies with sufficient follow-up duration, a detailed neuropsychological assessment and adequate control of main confounders.

OBJECTIVE

To investigate the relation between self-reported sleep quality and cognitive decline over 12 years in cognitively healthy individuals from the general population.

METHODS

We used data from the Maastricht Aging Study (MAAS), a Dutch population-based prospective cohort study of 1,823 community-dwelling adults aged 24 to 82 years at baseline. Cognitive performance was measured at baseline, 6 and 12 years on verbal memory, executive functions, and information processing speed. Sleep quality was assessed at baseline using the sleep subscale score of the 90-item Symptom Checklist (SCL-90). Additional modifiable dementia risk factors were summarized in the LIfestyle for BRAin health (LIBRA) risk score. Weighted linear mixed models tested the association between continuous scores and tertiles of subjective sleep quality and change in cognitive performances over time. Models were adjusted for age, gender, educational level, LIBRA, and use of hypnotic (sleep) medication.

RESULTS

Worse sleep quality was associated with faster decline in processing speed. At older age (≥65 years), it was also associated with faster decline in verbal memory. Association were independent of other modifiable dementia risk factors and use of hypnotic medication. Directionally similar but non-significant associations were found between worse sleep quality and executive functions.

CONCLUSIONS

In this population-based study across the adult age range, poor self-reported sleep was associated with accelerated cognitive decline.

Functional Connectivity of White Matter and Its Association with Sleep Quality

Purpose

Functional magnetic resonance imaging (fMRI) has been widely adopted to investigate the neural activity in gray matter (GM) in the field of sleep research, but the neural activity in white matter (WM) has received much less attention. The current study set out to test our hypothesis that WM functional abnormality is associated with poor sleep quality.

Participants and Methods

K-means clustering analysis was performed on 78 healthy adults drawn from the Human Connectome Project dataset to extract stable WM functional networks (WM-FNs) and GM-FNs. The differences in functional connectivity within WM-FNs and between WM- and GM-FNs, as well as the power spectrum between good sleep quality group (Pittsburgh Sleep Quality Index (PSQI) <6, daytime dysfunction = 0) and poor sleep quality group (PSQI >6, daytime dysfunction >0) were examined between groups with good and poor sleep quality. Additionally, linear relationships between sleep quality and altered functional characteristics of WM-FNs were evaluated.

Results

Functional connectivity between middle and superficial WM-FNs, short- and long-range functional connectivity between WM- and GM-FNs were decreased in poor sleepers and negatively correlated with PSQI score. The mean amplitudes of right sensorimotor WM networks at whole, high and low frequency bands were higher in poor sleepers and were positively correlated with PSQI score.

Conclusion

WM functional abnormality is associated with poor sleep quality. The neurobiological mechanisms that underlie the functional alterations of WM-FNs in poor sleepers need to be investigated in future studies.

Fatness, fitness and the aging brain: A cross sectional study of the associations between a physiological estimate of brain age and physical fitness, activity, sleep, and body composition

Introduction

Changes in brain structure and function occur with aging. However, there is substantial heterogeneity both in terms of when these changes begin, and the rate at which they progress. Understanding the mechanisms and/or behaviors underlying this heterogeneity may allow us to act to target and slow negative changes associated with aging.

Methods

Using T1 weighted MRI images, we applied a novel algorithm to determine the physiological age of the brain (brain-predicted age) and the predicted age difference between this physiologically based estimate and chronological age (BrainPAD) to 551 sedentary adults aged 65 to 84 with self-reported cognitive complaint measured at baseline as part of a larger study. We also assessed maximal aerobic capacity with a graded exercise test, physical activity and sleep with accelerometers, and body composition with dual energy x-ray absorptiometry. Associations were explored both linearly and logistically using categorical groupings.

Results

Visceral Adipose Tissue (VAT), Total Sleep Time (TST) and maximal aerobic capacity all showed significant associations with BrainPAD. Greater VAT was associated with higher (i.e,. older than chronological) BrainPAD (r = 0.149 p = 0.001)Greater TST was associated with higher BrainPAD (r = 0.087 p = 0.042) and greater aerobic capacity was associated with lower BrainPAD (r = - 0.088 p = 0.040). With linear regression, both VAT and TST remained significant (p = 0.036 and 0.008 respectively). Each kg of VAT predicted a 0.741 year increase in BrainPAD, and each hour of increased TST predicted a 0.735 year increase in BrainPAD. Maximal aerobic capacity did not retain statistical significance in fully adjusted linear models.

Discussion

Accumulation of visceral adipose tissue and greater total sleep time, but not aerobic capacity, total daily physical activity, or sleep quantity and/or quality are associated with brains that are physiologically older than would be expected based upon chronological age alone (BrainPAD).

White matter microstructure and sleep-wake disturbances in individuals at ultra-high risk of psychosis

Aim

White matter changes in individuals at ultra-high risk for psychosis (UHR) may be involved in the transition to psychosis. Sleep-wake disturbances commonly precede the first psychotic episode and predict development of psychosis. We examined associations between white matter microstructure and sleep-wake disturbances in UHR individuals compared to healthy controls (HC), as well as explored the confounding effect of medication, substance use, and level of psychopathology.

Methods

Sixty-four UHR individuals and 35 HC underwent clinical interviews and diffusion weighted imaging. Group differences on global and callosal mean fractional anisotropy (FA) was tested using general linear modeling. Sleep-wake disturbances were evaluated using the subjective measures disturbed sleep index (DSI) and disturbed awakening index (AWI) from the Karolinska Sleep Questionnaire, supported by objective sleep measures from one-night actigraphy. The primary analyses comprised partial correlation analyses between global FA/callosal FA and sleep-wake measures. Secondary analyses investigated multivariate patterns of covariance between measures of sleep-wake disturbances and FA in 48 white matter regions of interest using partial least square correlations.

Results

Ultra-high risk for psychosis individuals displayed lower global FA (F = 14.56, p < 0.001) and lower callosal FA (F = 11.34, p = 0.001) compared to HC. Subjective sleep-wake disturbances were significantly higher among the UHR individuals (DSI: F = 27.59, p < 0.001, AWI: F = 36.42, p < 0.001). Lower callosal FA was correlated with increased wake after sleep onset (r = -0.34, p = 0.011) and increased sleep fragmentation index (r = -0.31, p = 0.019) in UHR individuals. Multivariate analyses identified a pattern of covariance in regional FA which were associated with DSI and AWI in UHR individuals (p = 0.028), but not in HC. Substance use, sleep medication and antipsychotic medication did not significantly confound these associations. The association with objective sleep-wake measures was sustained when controlling for level of depressive and UHR symptoms, but symptom level confounded the covariation between FA and subjective sleep-wake measures in the multivariate analyses.

Conclusion

Compromised callosal microstructure in UHR individuals was related to objectively observed disruptions in sleep-wake functioning. Lower FA in ventrally located regions was associated with subjectively measured sleep-wake disturbances and was partly explained by psychopathology. These findings call for further investigation of sleep disturbances as a potential treatment target.

Impact of spaceflight stressors on behavior and cognition: A molecular, neurochemical, and neurobiological perspective

The response of the human body to multiple spaceflight stressors is complex, but mounting evidence implicate risks to CNS functionality as significant, able to threaten metrics of mission success and longer-term behavioral and neurocognitive health. Prolonged exposure to microgravity, sleep disruption, social isolation, fluid shifts, and ionizing radiation have been shown to disrupt mechanisms of homeostasis and neurobiological well-being. The overarching goal of this review is to document the existing evidence of how the major spaceflight stressors, including radiation, microgravity, isolation/confinement, and sleep deprivation, alone or in combination alter molecular, neurochemical, neurobiological, and plasma metabolite/lipid signatures that may be linked to operationally-relevant behavioral and cognitive performance. While certain brain region-specific and/or systemic alterations titrated in part with neurobiological outcome, variations across model systems, study design, and the conspicuous absence of targeted studies implementing combinations of spaceflight stressors, confounded the identification of specific signatures having direct relevance to human activities in space. Summaries are provided for formulating new research directives and more predictive readouts of portending change in neurobiological function.

Neural correlates of sleep quality in children: Sex-specific associations shown by brain diffusion tractography

BACKGROUND AND PURPOSE

Sleep quality is important for healthy growth and development of children. We aimed to identify associations between sleep disturbances in healthy children without clinical diagnosis of sleep disorders and brain white matter (WM) microstructure using an advanced diffusion-weighted magnetic resonance imaging (DW-MRI) based tractography analysis, and to explore whether there are sex differences in these associations.

METHODS

Brain DW-MRI data were collected from sixty-two 8-year-old children (28 boys, 34 girls) whose parents also completed Children's Sleep Habits Questionnaire (CSHQ). Track-weighted imaging (TWI) measures were computed from the DW-MRI data for 37 WM tracts in each subject. Sex-specific partial correlation analyses were performed to evaluate correlations between TWI measures and a set of sleep disturbance scores derived from the CSHQ.

RESULTS

Significant correlations (P < .05, FDR-corrected; r: .48-.67) were identified in 13 WM tracts between TWI and sleep disturbance scores. Sexually dimorphic differences in correlations between sleep disturbance scores and WM microstructure measurements were observed. Specifically, in boys, daytime sleepiness positively correlated with track-weighted mean or radial diffusivity in 10 WM tracts (bilateral arcuate fasciculus, left cingulum, right middle longitudinal fasciculus, and three bilateral segments of superior longitudinal fasciculus). In girls, total CSHQ score, night walking, or sleep onset delay negatively correlated with track-weighted fractional anisotropy or axial diffusivity in 4 WM tracts (bilateral inferior longitudinal fasciculus and uncinate fasciculus).

CONCLUSIONS

The findings suggest that sleep disturbances without clinical diagnosis of sleep disorders are associated with lower WM microstructural integrity in children. Additionally, the associations possess unique patterns in boys and girls.

Evidence of White Matter Integrity Changes in the Anterior Cingulum Among Shift Workers: A Cross-Sectional Study

INTRODUCTION

We investigated the white matter integrity in shift and non-shift workers and its associations with sleep and activity.

METHODS

Diffusion tensor imaging (DTI) was performed on 61 shift workers and 31 non-shift workers. Their sleep and activity profiles were assessed using the Pittsburgh Sleep Quality Index (PSQI), sleep diaries, and actigraphy. Fractional anisotropy (FA) (a measure of white matter integrity) was calculated using DTI tractography.

RESULTS

Shift workers exhibited higher FA values in the bilateral anterior cingulum than did non-shift workers. An increased FA in the right anterior cingulum was correlated with poor sleep quality (ie, a high PSQI score) in shift workers. An increased FA in the right anterior cingulum was also correlated with higher actigraphic activity indices (the mesor and M10 indices) in shift workers.

DISCUSSION

The white matter integrity of the anterior cingulum was altered in shift workers, perhaps in association with sleep and activity disturbances.

SJ, Martinez L, Manelis A, Iyengar S, Brent D, Ladouceur CD, Collins MW, Phillips ML, Versace A. The role of sleep quality on white matter integrity and concussion symptom severity in adolescents

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Poor sleepers showed lower NDI in several tracts relative to good sleepers.

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The effect of sleep quality was significant after seven days between injury and scan.

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Good sleepers showed no differences relative to non-concussed controls.

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Significant relationship between low NDI, poor sleep, and higher symptom severity.

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Being female and low NDI significantly correlate with higher severity of symptoms.

Background

Sleep problems are common after concussion; yet, to date, no study has evaluated the relationship between sleep, white matter integrity, and post-concussion symptoms in adolescents. Using self-reported quality of sleep measures within the first 10 days of injury, we aimed to determine if quality of sleep exerts a main effect on white matter integrity in major tracts, as measured by diffusion Magnetic Resonance Imaging (dMRI), and further examine whether this effect can help explain the variance in post-concussion symptom severity in 12- to 17.9-year-old adolescents.

Methods

dMRI data were collected in 57 concussed adolescents (mean age[SD] = 15.4[1.5] years; 41.2 % female) with no history of major psychiatric diagnoses. Severity of post-concussion symptoms was assessed at study entry (mean days[SD] = 3.7[2.5] days since injury). Using the Pittsburgh Sleep Quality Index (PSQI), concussed adolescents were divided into two groups based on their quality of sleep in the days between injury and scan: good sleepers (PSQI global score ≤ 5; N = 33) and poor sleepers (PSQI global score > 5; N = 24). Neurite Orientation Dispersion and Dispersion Index (NODDI), specifically the Neurite Density Index (NDI), was used to quantify microstructural properties in major tracts, including 18 bilateral and one interhemispheric tract, and identify whether dMRI differences existed in good vs poor sleepers. Since the interval between concussion and neuroimaging acquisition varied among concussed adolescents, this interval was included in the analysis along with an interaction term with sleep groups. Regularized regression was used to identify if quality of sleep-related dMRI measures correlated with post-concussion symptom severity. Due to higher reported concussion symptom severity in females, interaction terms between dMRI and sex were included in the regularized regression model. Data collected in 33 sex- and age-matched non-concussed controls (mean age[SD] = 15.2[1.5]; 45.5 % female) served as healthy reference and sex and age were covariates in all analyses.

Results

Relative to good sleepers, poor sleepers demonstrated widespread lower NDI (18 of the 19 tracts; FDR corrected P < 0.048). This group effect was only significant with at least seven days between concussion and neuroimaging acquisition. Post-concussion symptoms severity was negatively correlated with NDI in four of these tracts: cingulum bundle, optic radiation, striato-fronto-orbital tract, and superior longitudinal fasciculus I. The multiple linear regression model combining sex and NDI of these four tracts was able to explain 33.2 % of the variability in symptom severity (F[7,49] = 4.9, P < 0.001, Adjusted R² = 0.332). Relative to non-concussed controls, poor sleepers demonstrated lower NDI in the cingulum bundle, optic radiation, and superior longitudinal fasciculus I (FDR corrected P < 0.040).

Conclusions

Poor quality of sleep following concussion is associated with widespread lower integrity of major white matter tracts, that in turn helped to explain post-concussion symptom severity in 12–17.9-year-old adolescents. The effect of sleep on white matter integrity following concussion was significant after one week, suggesting that acute sleep interventions may need this time to begin to take effect. Our findings may suggest an important relationship between good quality of sleep in the days following concussion and integrity of major white matter tracts. Moving forward, researchers should evaluate the effectiveness of sleep interventions on white matter integrity and clinical outcomes following concussion.

Nighttime Sleep Characteristics and White Matter Integrity in Young Adults

PURPOSE

Sleep is essential for life and plays a key role for optimal physiology, brain functioning, and health. Evidence suggests a relation between sleep and cerebral white matter integrity. Human studies report that sleep duration shows a U-shaped association with brain functioning. We hypothesized that participants with longer or shorter sleep time in the nighttime period show altered microstructural white matter integrity.

PARTICIPANTS AND METHODS

Seventy-three young adult participants were evaluated. Sleep-wake cycle parameters were assessed objectively using actigraphy. Diffusion tensor imaging studies were performed to assess white matter integrity using fractional anisotropy and mean, axial, and radial diffusivities. Relations between white matter microstructure indexes and sleep parameters were investigated through tract-based spatial statistics. Participants were grouped according to their nocturnal total sleep time: 27 in the Reference sleep group (6.5-8.0 h), 23 in the Short sleep group (<6.5 h) and 23 in the Long sleep group (>8.0 h).

RESULTS

Compared with the Reference sleep group, participants in the Long sleep group showed lower fractional anisotropy (p < 0.05) and higher radial diffusivity (p < 0.05) values in white matter tracts linked to sleep regulation (corona radiata, body of the corpus callosum, superior longitudinal fasciculus, and anterior thalamic radiation).

CONCLUSION

This pattern of reduced fractional anisotropy and increased radial diffusivity in the Long sleep group indicates an association between sleep duration and lower integrity of myelin sheaths. Because myelin is continuously remodeled in the brain, nighttime sleep characteristics appear to be a key player for its quality and maintenance.

Association of white matter volume with sleep quality: a voxel-based morphometry study

Many studies have focused on the gray matter volume associated with sleep quality, little is known about the relationship between white matter volume and sleep quality. Brain white structure is a crucial component in the structural neuroanatomy. Therefore, in this study, we investigated the association between white matter volume and sleep quality. Data were collected using the Pittsburgh Sleep Quality Index and voxel-based morphometry among 352 college students. Results showed that the global PSQI score was negatively associated with the white matter volume, including in the right middle occipital gyrus, the left superior temporal gyrus, the right the precentral gyrus, the left supramarginal gyrus, the left middle frontal gyrus, the left precunes, and the right superior frontal gyrus. Results also indicated that the white matter volume in specific regions negatively associated with the factor of PSQI. These specific brain regions may be replicated in brain areas related to sleep quality. In summary, we suggested that exploring brain white structure are related to sleep could help to expound the mechanisms by which sleep quality are associated with brain function, behavior and cognition, as well as potentially the networks and systems responsible for variations in sleep themselves.

Regional neurodegeneration correlates with sleep-wake dysfunction after stroke

Sleep-wake disruption is a key modifiable risk factor and sequela of stroke. The pathogenesis of poststroke sleep dysfunction is unclear. It is not known whether poststroke sleep pathology is due to focal infarction to sleep-wake hubs or to accelerated poststroke neurodegeneration in subcortical structures after stroke. We characterize the first prospective poststroke regional brain volumetric and whole-brain, fiber-specific, white matter markers of objectively measured sleep-wake dysfunction. We hypothesized that excessively long sleep (>8 h) duration and poor sleep efficiency (<80%) measured using the SenseWear Armband 3-months poststroke (n = 112) would be associated with reduced regional brain volumes of a priori-selected sleep-wake regions of interest when compared to healthy controls with optimal sleep characteristics (n = 35). We utilized a novel technique known as a whole-brain fixel-based analysis to investigate the fiber-specific white matter differences in participants with long sleep duration. Stroke participants with long sleep (n = 24) duration exhibited reduced regional volumes of the ipsilesional thalamus and contralesional amygdala when compared with controls. Poor sleep efficiency after stroke (n = 29) was associated with reduced ipsilesional thalamus, contralesional hippocampus, and contralesional amygdala volumes. Whole-brain fixel-based analyses revealed widespread macrostructural degeneration to the corticopontocerebellar tract in stroke participants with long sleep duration, with fiber reductions of up to 40%. Neurodegeneration to subcortical structures, which appear to be vulnerable to accelerated brain volume loss after stroke, may drive sleep-wake deficiencies poststroke, independent of lesion characteristics and confounding comorbidities. We discuss these findings in the context of the clinicopathological implications of sleep-related neurodegeneration and attempt to corroborate previous mechanistic-neuroanatomical findings.

Sleep characteristics and white matter hyperintensities among midlife women

STUDY OBJECTIVES

Sleep disturbance is common among midlife women. Poor self-reported sleep characteristics have been linked to cerebrovascular disease and dementia risk. However, little work has considered the relation of objectively assessed sleep characteristics and white matter hyperintensities (WMHs), a marker of small vessel disease in the brain. Among 122 midlife women, we tested whether women with short or disrupted sleep would have greater WMH, adjusting for cardiovascular disease (CVD) risk factors, estradiol, and physiologically assessed sleep hot flashes.

METHODS

We recruited 122 women (mean age = 58 years) without a history of stroke or dementia who underwent 72 h of actigraphy to quantify sleep, 24 h of physiologic monitoring to quantify hot flashes; magnetic resonance imaging to assess WMH; phlebotomy, questionnaires, and physical measures (blood pressure, height, and weight). Associations between actigraphy-assessed sleep (wake after sleep onset and total sleep time) and WMH were tested in linear regression models. Covariates included demographics, CVD risk factors (blood pressure, lipids, and diabetes), estradiol, mood, and sleep hot flashes.

RESULTS

Greater actigraphy-assessed waking after sleep onset was associated with more WMH [B(SE) = .008 (.002), p = 0.002], adjusting for demographics, CVD risk factors, and sleep hot flashes. Findings persisted adjusting for estradiol and mood. Neither total sleep time nor subjective sleep quality was related to WMH.

CONCLUSIONS

Greater actigraphy-assessed waking after sleep onset but not subjective sleep was related to greater brain WMH among midlife women. Poor sleep may be associated with brain small vessel disease at midlife, which can increase the risk for brain disorders.

Evidence of Genetic Overlap Between Circadian Preference and Brain White Matter Microstructure

Several neuroimaging studies have reported associations between brain white matter microstructure and chronotype. However, it is unclear whether those phenotypic relationships are causal or underlined by genetic factors. In the present study, we use genetic data to examine the genetic overlap and infer causal relationships between chronotype and diffusion tensor imaging (DTI) measures. We identify 29 significant pairwise genetic correlations, of which 13 also show evidence for a causal association. Genetic correlations were identified between chronotype and brain-wide mean, axial and radial diffusivities. When exploring individual tracts, 10 genetic correlations were observed with mean diffusivity, 10 with axial diffusivity, 4 with radial diffusivity and 2 with mode of anisotropy. We found evidence for a possible causal association of eveningness with white matter microstructure measures in individual tracts including the posterior limb and the retrolenticular part of the internal capsule; the genu and splenium of the corpus callosum and the posterior, superior and anterior regions of the corona radiata. Our findings contribute to the understanding of how genes influence circadian preference and brain white matter and provide a new avenue for investigating the role of chronotype in health and disease.

Contribution of sleep disturbances to the heterogeneity of cognitive and brain alterations in alcohol use disorder

Cognitive and brain alterations are common in alcohol use disorder and vary importantly from one patient to another. Sleep disturbances are also very frequent in these patients and remain largely neglected even though they can persist after drinking cessation. Sleep disturbances may be the consequence of specific brain alterations, resulting in cognitive impairments. But sleep disruption may also exacerbate alcohol-related brain abnormalities and cognitive deficits through common pathophysiological mechanisms. Besides, sleep disturbances seem a vulnerability factor for the development of alcohol use disorder. From a clinical perspective, sleep disturbances are known to affect treatment outcome and to increase the risk of relapse. In this article, we conducted a narrative review to provide a better understanding of the relationships between sleep disturbances, brain and cognition in alcohol use disorder. We suggest that the heterogeneity of brain and cognitive alterations observed in patients with alcohol use disorder could at least partially be explained by associated sleep disturbances. We also believe that sleep disruption could indirectly favor relapse by exacerbating neuropsychological impairments required in psychosocial treatment and for the maintenance of abstinence. Implications for clinical practice as well as perspectives for future research are proposed.

White Matter Microstructure Underlies the Effects of Sleep Quality and Life Stress on Depression Symptomatology in Older Adults

Sleep complaints are the most prevalent syndromes in older adults, particularly in women. Moreover, they are frequently accompanied with a high level of depression and stress. Although several diffusion tensor imaging (DTI) studies reported associations between sleep quality and brain white matter (WM) microstructure, it is still unclear whether gender impacts the effect of sleep quality on structural alterations, and whether these alterations mediate the effects of sleep quality on emotional regulation. We included 389 older participants (176 females, age = 65.5 ± 5.5 years) from the 1000BRAINS project. Neuropsychological examinations covered the assessments of sleep quality, depressive symptomatology, current stress level, visual working memory, and selective attention ability. Based on the DTI dataset, the diffusion parameter maps, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), were calculated and normalized to a population-specific FA template. According to the global Pittsburgh Sleep Quality Index (PSQI), 119 poor sleepers (PSQI: 10∼17) and 120 good sleepers (PSQI: 3∼6) were identified. We conducted a two by two (good sleepers/poor sleepers) × (males/females) analysis of variance by using tract-based spatial statistics (TBSS) and JHU-ICBM WM atlas-based comparisons. Moreover, we performed a voxel-wise correlation analysis of brain WM microstructure with the neuropsychological tests. Finally, we applied a mediation analysis to explore if the brain WM microstructure mediates the relationship between sleep quality and emotional regulation. No significant differences in brain WM microstructure were detected on the main effect of sleep quality. However, the MD, AD, and RD of pontine crossing tract and bilateral inferior cerebellar peduncle were significant lower in the males than females. Voxel-wise correlation analysis revealed that FA and RD values in the corpus callosum were positively related with depressive symptomatology and negatively related with current stress levels. Additionally, we found a significantly positive association between higher FA values in visual-related WM tracts and better outcomes in a visual pattern recognition test. Furthermore, a mediation analysis suggested that diffusion metrics within the corpus callosum partially mediated the associations between poor sleep quality/high stress and depressive symptomatology.

Neurobiological changes during the peripartum period: implications for health and behavior

Pregnancy and the transition to parenthood is an important period marked by dramatic neurobiological and psychosocial changes that may have implications for the health of women and offspring. Although human and non-human animal research suggests that the brain undergoes alterations during the peripartum period, these changes are poorly understood. Here, we review existing research, particularly human neuroimaging and psychophysiological research, to examine changes in brain structure and function during the peripartum period and discuss potential implications for the health of women and offspring. First, we discuss the potential causes of these changes across pregnancy, including physiological and psychosocial factors. Next, we discuss the evidence for structural and functional changes in the brain during pregnancy and into the postpartum period, noting the need for research conducted prospectively across human pregnancy. Finally, we propose potential models of individual differences in peripartum neurobiological changes (i.e. hypo-response, typical response, hyper-response) and emphasize the need to consider trajectories of change in addition to pre-existing factors that may predict maternal adjustment to parenthood. We suggest that the consideration of individual differences in neurobiological trajectories across pregnancy may contribute to a better understanding of risk for negative health and behavior outcomes for women and offspring.

Brain mechanisms of insomnia: new perspectives on causes and consequences

While insomnia is the second most common mental disorder, progress in our understanding of underlying neurobiological mechanisms has been limited. The present review addresses the definition and prevalence of insomnia and explores its subjective and objective characteristics across the 24-hour day. Subsequently, the review extensively addresses how the vulnerability to develop insomnia is affected by genetic variants, early life stress, major life events, and brain structure and function. Further supported by the clear mental health risks conveyed by insomnia, the integrated findings suggest that the vulnerability to develop insomnia could rather be found in brain circuits regulating emotion and arousal than in circuits involved in circadian and homeostatic sleep regulation. Finally, a testable model is presented. The model proposes that in people with a vulnerability to develop insomnia, the locus coeruleus is more sensitive to-or receives more input from-the salience network and related circuits, even during rapid eye movement sleep, when it should normally be sound asleep. This vulnerability may ignite a downward spiral of insufficient overnight adaptation to distress, resulting in accumulating hyperarousal, which, in turn, impedes restful sleep and moreover increases the risk of other mental health adversity. Sensitized brain circuits are likely to be subjectively experienced as "sleeping with one eye open". The proposed model opens up the possibility for novel intervention studies and animal studies, thus accelerating the ignition of a neuroscience of insomnia, which is direly needed for better treatment.

Sleep duration is associated with white matter microstructure and cognitive performance in healthy adults

Reduced sleep duration and sleep deprivation have been associated with cognitive impairment as well as decreased white matter integrity as reported by experimental studies. However, it is largely unknown whether differences in sleep duration and sleep quality might affect microstructural white matter and cognition. Therefore, the present study aims to examine the cross‐sectional relationship between sleep duration, sleep quality, and cognitive performance in a naturalistic study design, by focusing on the association with white matter integrity in a large sample of healthy, young adults. To address this, 1,065 participants, taken from the publicly available sample of the Human Connectome Project, underwent diffusion tensor imaging. Moreover, broad cognitive performance measures (NIH Cognition Toolbox) and sleep duration and quality (Pittsburgh Sleep Quality Index) were assessed. The results revealed a significant positive association between sleep duration and overall cognitive performance. Shorter sleep duration significantly correlated with fractional anisotropy (FA) reductions in the left superior longitudinal fasciculus (SLF). In turn, FA in this tract was related to measures of cognitive performance and was shown to significantly mediate the association of sleep duration and cognition. For cognition only, associations shift to a negative association of sleep duration and cognition for participants sleeping more than 8 hr a day. Investigations into subjective sleep quality showed no such associations. The present study showed that real‐world differences in sleep duration, but not subjective sleep quality are related to cognitive performance measures and white matter integrity in the SLF in healthy, young adults.

The prospective association of objectively measured sleep and cerebral white matter microstructure in middle-aged and older persons

STUDY OBJECTIVES

Poor sleep may destabilize axonal integrity and deteriorate cerebral white matter. In middle-aged and older adults sleep problems increase alongside structural brain changes, but the temporal relation between these processes is poorly understood. We studied longitudinal associations between sleep and cerebral white matter microstructure.

METHODS

One thousand one persons (59.3 ± 7.9 years, 55% women) were followed across 5.8 years (3.9-10.8). Total sleep time (TST, hours), sleep efficiency (SE, percentage), sleep onset latency (SOL, minutes), and wake after sleep onset (WASO, minutes) were measured at baseline using a wrist-worn actigraph. White matter microstructure (global and tract-specific fractional anisotropy [FA] and mean diffusivity [MD]) was measured twice with diffusion tensor imaging (DTI).

RESULTS

Poor sleep was associated with worse white matter microstructure up to 7 years later but did not predict trajectories of DTI over time. Longer TST was associated with higher global FA (β = 0.06, 95% CI: 0.01 to 0.12), but not with MD. Persons with higher SE had higher global FA (β = 0.01, 95% CI: 0.002 to 0.01) and lower MD (β = -0.01, 95% CI: -0.01 to -0.0004). Consistently, those with more WASO had lower global FA (β = -0.003, 95% CI: -0.005 to -0.001) and higher MD (β = 0.002, 95% CI: 0.0004 to 0.004). Global findings seemed to be driven by microstructural alterations in the cingulum, anterior forceps of corpus callosum, projection and association tracts.

CONCLUSIONS

Middle-aged and older persons with more WASO, lower SE and shorter TST have worse microstructure of cerebral white matter. Microstructural alterations are most pronounced projection and association tracts, in the cingulum, and in the anterior forceps of corpus callosum.

Shorter sleep duration is associated with lower GABA levels in the anterior cingulate cortex

BACKGROUND

Alterations in the levels of gamma-aminobutyric acid (GABA) and glutamate + glutamine (Glx), which are major inhibitory and excitatory neurotransmitters, respectively, are frequently associated with insomnia. Previous reports also suggested the involvement of the anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) in insomnia and shorter sleep duration. In the current study, we investigated whether the GABA and Glx levels were altered in the ACC/mPFC in subclinical insomnia while focusing on the sleep duration.

METHODS

We examined levels of GABA and Glx in the ACC/mPFC of the brain with magnetic resonance spectroscopy in 166 individuals with subjective sleep complaints but without a diagnosis of insomnia. Participants were divided into two groups according to sleep duration (≥6 h/night: n = 79 vs. < 6 h/night: n = 74), which was measured using a wrist-worn actigraphy. Working memory function and overall subjective sleep quality were assessed with a computerized neuropsychological test and self-report questionnaire, respectively.

RESULTS

GABA levels in the ACC/mPFC were lower in the shorter sleep duration group relative to the longer sleep duration group (t = -2.21, p = 0.03). Glx levels did not differ between the two groups (t = -0.20, p = 0.84). Lower GABA levels were associated with lower spatial working memory performance in the shorter sleep duration group (β = -0.21, p = 0.03), but not the longer sleep duration group (β = 0.04, p = 0.72).

CONCLUSION

Shorter sleep duration was associated with lower GABA levels in the ACC/mPFC. These findings may provide insight into the underlying mechanisms of impaired working memory function related to insomnia and sleep loss.

Circadian phenotype impacts the brain's resting-state functional connectivity, attentional performance, and sleepiness

INTRODUCTION

Functional connectivity (FC) of the human brain's intrinsically connected networks underpins cognitive functioning and disruptions of FC are associated with sleep and neurological disorders. However, there is limited research on the impact of circadian phenotype and time of day on FC.

STUDY OBJECTIVES

The aim of this study was to investigate resting-state FC of the default mode network (DMN) in Early and Late circadian phenotypes over a socially constrained day.

METHODS

Thirty-eight healthy individuals (14 male, 22.7 ± 4.2 years) categorized as Early (n = 16) or Late (n = 22) using the Munich ChronoType Questionnaire took part. Following a 2-week baseline of actigraphy coupled with saliva samples for melatonin and cortisol rhythms, participants underwent testing at 14:00 hours, 20:00 hours, and 08:00 hours the following morning. Testing consisted of resting-state functional magnetic resonance imaging (fMRI), a structural T1 scan, attentional cognitive performance tasks, and self-reported daytime sleepiness. Seed-based FC analysis from the medial prefrontal and posterior cingulate cortices of the DMN was performed, compared between groups and linked with behavioral data.

RESULTS

Fundamental differences in the DMN were observed between Early and Late circadian phenotypes. Resting-state FC of the DMN predicted individual differences in attention and subjective ratings of sleepiness.

CONCLUSION

Differences in FC of the DMN may underlie the compromised attentional performance and increased sleepiness commonly associated with Late types when they conform to a societally constrained day that does not match their intrinsic circadian phenotype.

Sleep complaints and cerebral white matter: A prospective bidirectional study

Sleep complaints and brain changes co-occur in older adulthood, but the temporal relation between these processes is poorly understood. Poor sleep may destabilize axonal integrity and deteriorate white matter, but white matter pathology can also precede sleep complaints. Our objective was to explore a prospective, possibly bi-directional association between subjective sleep complaints and micro- and macro-structural properties of cerebral white matter. We assessed sleep complaints and brain magnetic resonance imaging at two time-points (2006-2008 and 2011-2014) in a population-based cohort including 2529 participants (56 ± 6 years old, 55% women). Sleep complaints were assessed with the Pittsburgh Sleep Quality Index. White matter lesion (WML) volume was assessed from fluid-attenuated inversion recovery images and global and tract-specific white matter microstructural integrity with diffusion tensor imaging. Sleep complaints at baseline were not associated with changes in WML volume or global white matter microstructure. In tract-specific analyses, however, sleep complaints were associated with reduced microstructural integrity in two white matter tracts projecting to the brainstem, but only when uncorrected for multiple testing. Likewise, we found no evidence for the reverse association; micro- or macro-structural properties of white matter were not related to changes in sleep complaints over time. This study provides evidence against the hypothesis that sleep complaints lead to white matter changes in the aging brain, and shows that white matter properties do not underlie sleep complaints in older persons. As subjective sleep complaints increase in later life, it is important to demonstrate that these are not etiologically related to cerebral white matter pathology.

Associations between modifiable risk factors and white matter of the aging brain: insights from diffusion tensor imaging studies

There is increasing interest in factors that may modulate white matter (WM) breakdown and, consequentially, age-related cognitive and behavioral deficits. Recent diffusion tensor imaging studies have examined the relationship of such factors with WM microstructure. This review summarizes the evidence regarding the relationship between WM microstructure and recognized modifiable factors, including hearing loss, hypertension, diabetes, obesity, smoking, depressive symptoms, physical (in) activity, and social isolation, as well as sleep disturbances, diet, cognitive training, and meditation. Current cross-sectional evidence suggests a clear link between loss of WM integrity (lower fractional anisotropy and higher mean diffusivity) and hypertension, obesity, diabetes, and smoking; a relationship that seems to hold for hearing loss, social isolation, depressive symptoms, and sleep disturbances. Physical activity, cognitive training, diet, and meditation, on the other hand, may protect WM with aging. Preliminary evidence from cross-sectional studies of treated risk factors suggests that modification of factors could slow down negative effects on WM microstructure. Careful intervention studies are needed for this literature to contribute to public health initiatives going forward.

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Both aging and dementia are associated with breakdown of white matter (WM) microstructure.

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We review a range of modifiable factors that could prevent or slow age-related WM decline.

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Risk factors are consistently related with lower fractional anisotropy and higher mean diffusivity.

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Treatment of risk factors may slow WM decline.

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Careful longitudinal and intervention studies are now needed.