Abnormalities of thalamus volume and resting state functional connectivity in primary insomnia patients

Poor sleep quality is associated with decreased regional brain glucose metabolism in healthy middle-aged adults

Sleep disturbance is associated with the development of neurodegenerative disease. We aimed to address the effects of sleep quality on brain glucose metabolism measured by 18F-Fl uorodeoxyglucose (18F-FDG) positron emission tomography (PET) in healthy middle-aged adults. A total of 378 healthy men (mean age: 42.8±3.6 years) were included in this study. Participants underwent brain 18F-FDG PET and completed the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K). Additionally, anthropometric measurements were obtained. PETs were spatially normalized to MNI space using PET templates from SPM5 with PMOD. The Automated Anatomical Labeling 2 atlas was used to define regions of interest (ROIs). The mean uptake of each ROI was scaled to the mean of the global cortical uptake of each individual and defined as the standardized uptake value ratio (SUVR). After the logarithmic transformation of the regional SUVR, the effects of the PSQI-K on the regional SUVR were investigated using Bayesian hierarchical modeling. Brain glucose metabolism of the posterior cingulate, precuneus, and thalamus showed a negative association with total PSQI-K scores in the Bayesian model ROI-based analysis. Voxel-based analysis using statistical parametric mapping revealed a negative association between the total PSQI-K scores and brain glucose metabolism of the precuneus, postcentral gyrus, posterior cingulate, and thalamus. Poor sleep quality is negatively associated with brain glucose metabolism in the precuneus, posterior cingulate, and thalamus. Therefore, the importance of sleep should not be overlooked, even in healthy middle-aged adults.

Acupuncture modulates emotional network resting-state functional connectivity in patients with insomnia disorder: a randomized controlled trial and fMRI study

BACKGROUND

Insomnia disorder (ID) is one of the most common sleep problems, usually accompanied by anxiety and depression symptoms. Functional magnetic resonance imaging (fMRI) study suggests that both poor sleep quality and negative emotion are linked to the dysregulation of brain network related to emotion processing in ID patients. Acupuncture therapy has been proven effective in improving sleep quality and mood of ID patients, but the involved neurobiological mechanism remains unclear. We aimed to investigate the modulation effect of acupuncture on resting-state functional connectivity (rsFC) of the emotional network (EN) in patients experiencing insomnia.

METHODS

A total of 30 healthy controls (HCs) and 60 ID patients were enrolled in this study. Sixty ID patients were randomly assigned to real and sham acupuncture groups and attended resting-state fMRI scans before and after 4 weeks of acupuncture treatment. HCs completed an MRI/fMRI scan at baseline. The rsFC values within EN were calculated, and Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD), Pittsburgh Sleep Quality Index (PSQI), Hyperarousal Scale (HAS), and actigraphy data were collected for clinical efficacy evaluation.

RESULTS

Resting-state FC analysis showed abnormalities in rsFC centered on the thalamus and dorsolateral prefrontal cortex within EN of ID patients compared to HCs. After real acupuncture treatment, rsFC of the anterior cingulate cortex, hippocampus, and amygdala were increased compared with the sham acupuncture group (p < 0.05, FDR corrected). In real acupuncture group, the rsFC value was decreased between left amygdala and left thalamus after 4 weeks of treatment compared with baseline. A trend of correlation was found that the increased rsFC value between the right amygdala and left hippocampus was positively correlated with the decreased HAMA scores across all ID patients, and the decreased left amygdala rsFC value with the left thalamus was negatively correlated with the increased sleep efficiency in the real acupuncture group.

CONCLUSION

Our findings showed that real acupuncture could produce a positive effect on modulating rsFC within network related to emotion processing in ID patients, which may illustrate the central mechanism underlying acupuncture for insomnia in improving sleep quality and emotion regulation.

TRIAL REGISTRATION

http://www.chictr.org.cn ., ChiCTR1800015282, 20/03/2018.

The subcortical basis of subjective sleep quality

Study objectives

To assess the association between self-reported sleep quality and cortical and subcortical local morphometry.

Methods

Sleep and neuroanatomical data from the full release of the young adult Human Connectome Project dataset were analyzed. Sleep quality was operationalized with the Pittsburgh Sleep Quality Index (PSQI). Local cortical and subcortical morphometry was measured with subject-specific segmentations resulting in voxelwise thickness measurements for cortex and relative (i.e., cross-sectional) local atrophy measurements for subcortical regions.

Results

Relative atrophy across several subcortical regions, including bilateral pallidum, striatum, and thalamus, was negatively associated with both global PSQI score and sub-components of the index related to sleep duration, efficiency, and quality. Conversely, we found no association between cortical morphometric measurements and self-reported sleep quality.

Conclusions

This work shows that subcortical regions such as the bilateral pallidum, thalamus, and striatum, might be interventional targets to ameliorate self-reported sleep quality.

Repeated caffeine intake suppresses cerebral grey matter responses to chronic sleep restriction in an A1 adenosine receptor-dependent manner: a double-blind randomized controlled study with PET-MRI

Evidence has shown that both sleep loss and daily caffeine intake can induce changes in grey matter (GM). Caffeine is frequently used to combat sleepiness and impaired performance caused by insufficient sleep. It is unclear (1) whether daily use of caffeine could prevent or exacerbate the GM alterations induced by 5-day sleep restriction (i.e. chronic sleep restriction, CSR), and (2) whether the potential impact on GM plasticity depends on individual differences in the availability of adenosine receptors, which are involved in mediating effects of caffeine on sleep and waking function. Thirty-six healthy adults participated in this double-blind, randomized, controlled study (age = 28.9 ± 5.2 y/; F:M = 15:21; habitual level of caffeine intake < 450 mg; 29 homozygous C/C allele carriers of rs5751876 of ADORA2A, an A2A adenosine receptor gene variant). Each participant underwent a 9-day laboratory visit consisting of one adaptation day, 2 baseline days (BL), 5-day sleep restriction (5 h time-in-bed), and a recovery day (REC) after an 8-h sleep opportunity. Nineteen participants received 300 mg caffeine in coffee through the 5 days of CSR (CAFF group), while 17 matched participants received decaffeinated coffee (DECAF group). We examined GM changes on the 2nd BL Day, 5th CSR Day, and REC Day using magnetic resonance imaging and voxel-based morphometry. Moreover, we used positron emission tomography with [18F]-CPFPX to quantify the baseline availability of A1 adenosine receptors (A1R) and its relation to the GM plasticity. The results from the voxel-wise multimodal whole-brain analysis on the Jacobian-modulated T1-weighted images controlled for variances of cerebral blood flow indicated a significant interaction effect between caffeine and CSR in four brain regions: (a) right temporal-occipital region, (b) right dorsomedial prefrontal cortex (DmPFC), (c) left dorsolateral prefrontal cortex (DLPFC), and (d) right thalamus. The post-hoc analyses on the signal intensity of these GM clusters indicated that, compared to BL, GM on the CSR day was increased in the DECAF group in all clusters  but decreased in the thalamus, DmPFC, and DLPFC in the CAFF group. Furthermore, lower baseline subcortical A1R availability predicted a larger GM reduction in the CAFF group after CSR of all brain regions except for the thalamus. In conclusion, our data suggest an adaptive GM upregulation after 5-day CSR, while concomitant use of caffeine instead leads to a GM reduction. The lack of consistent association with individual A1R availability may suggest that CSR and caffeine affect thalamic GM plasticity predominantly by a different mechanism. Future studies on the role of adenosine A2A receptors in CSR-induced GM plasticity are warranted.

Towards the neurobiology of insomnia: A systematic review of neuroimaging studies

Insomnia disorder signifies a major public health concern. The development of neuroimaging techniques has permitted to investigate brain mechanisms at a structural and functional level. The present systematic review aims at shedding light on functional, structural, and metabolic substrates of insomnia disorder by integrating the available published neuroimaging data. The databases PubMed, PsycARTICLES, PsycINFO, CINAHL and Web of Science were searched for case-control studies comparing neuroimaging data from insomnia patients and healthy controls. 85 articles were judged as eligible. For every observed finding of each study, the effect size was calculated from standardised mean differences, statistic parameters and figures, showing a marked heterogeneity that precluded a comprehensive quantitative analysis. From a qualitative point of view, considering the findings of significant group differences in the reported regions across the articles, this review highlights the major involvement of the anterior cingulate cortex, thalamus, insula, precuneus and middle frontal gyrus, thus supporting some central themes in the debate on the neurobiology of and offering interesting insights into the psychophysiology of sleep in this disorder.

Neuroimaging in insomnia: Review and reconsiderations

Over the last decades, neuroimaging has become a substantial component of insomnia research. While theoretical underpinnings of different studies vary just like methodological choices and the experimental design, it is suggested that major features of insomnia disorder rely on the impaired function, structure, metabolism and connectivity of brain areas involved in sleep generation, emotion regulation, self-processing/-awareness and attentional orientation. However, neuroimaging research on insomnia often suffers from small sample sizes, heterogeneous methodology and a lack of replicability. With respect to these issues, the field needs to address the questions: (1a) how sufficiently large sample sizes can be accumulated within a reasonable economic framework; (1b) how effect sizes in insomnia-related paradigms can be amplified; (2a) how a higher degree of standardisation and transparency in methodology can be provided; and (2b) how an adequate amount of flexibility/complexity in study design can be maintained. On condition that methodological consistency and a certain degree of adaptability are given, pooled data/large cohort analyses can be considered to be one way to answer these questions. Regarding experimental single-centre trials, it might be helpful to focus on insomnia-related transdiagnostic concepts. In doing so, expectable effect sizes (in between-subjects designs) can be increased by: (a) comparing groups that are truly distinct regarding the variables examined in a concept-specific paradigm; and (b) facilitated, intensified and precise elicitation of a target symptom.

Plasma Aβ level alterations after sleep deprivation correspond to brain structural remodeling in medical night shift workers

The relationship between brain structure alteration and metabolic product clearance after night shift work with total sleep deprivation (SD) remains unclear. Twenty-two intensive care unit staff on regularly rotating shift work were implemented with structural and diffusion MRI under both rest wakefulness (RW) and SD conditions. Peripheral blood samples were collected for the measurement of cerebral metabolites. Voxel-based morphometry and diffusion tensor imaging analysis were used to investigate the alterations in the gray matter density (GMD) and mean diffusivity (MD) within the participants. Furthermore, correlation analysis was performed to investigate the relationship between the neuroimaging metrics and hematological parameters. A significant increase in the GMD values was observed in the anterior and peripheral areas of the brain under SD. In contrast, a decrease in the values was observed in the posterior regions, such as the bilateral cerebellum and thalamus. In addition, a significant reduction in the total cerebrospinal fluid volume was observed under SD. The Aβ42/Aβ40 levels in participants under SD were significantly lower than those under RW. The mean MD increment values extracted from the region of interest (ROI) of the anterior brain were negatively correlated with the increment of plasma Aβ42/Aβ40 levels (r = -0.658, P = 0.008). The mean GMD decrement values extracted from the posterior ROI were positively correlated with the increment of plasma Aβ-40 levels (r = 0.601, P = 0.023). The findings of this study suggest that one night of shift work under SD induces extensive and direction-specific structural alterations of the brain, which are associated with aberrant brain metabolic waste clearance.

Altered functional connectivity of the thalamus in patients with insomnia disorder after transcutaneous auricular vagus nerve stimulation therapy

The pathogenesis of insomnia is related to the dysfunction of the thalamus. Transcutaneous auricular vagus nerve stimulation (taVNS) has proved to be effective in treating insomnia. However, whether taVNS alleviates insomnia through modulating thalamus-related functional connectivity remains unclear. To elucidate the instant modulating effects of taVNS on the resting state functional connectivity (RSFC) of the thalamus, 20 patients with insomnia disorder were recruited to receive taVNS treatment and their resting state functional magnetic resonance imaging (fMRI) data were collected immediately before and after stimulation. The fMRI data were compared with 20 age- and gender-matched healthy subjects who received no stimulation and had RSFC fMRI data collected once. RSFC analyses of the thalamus were performed in both groups. In addition to assessing the group differences between ID patients and healthy controls regarding the RSFC of the thalamus, we examined the taVNS-induced changes of RSFC of the thalamus in ID patients. Before taVNS treatment, the ID patients showed increased RSFC of the thalamus with the right insula and inferior frontal gyrus than healthy controls. After taVNS treatment, the RSFC between the thalamus and the right angular gyrus, left anterior cingulate gyrus, and precuneus were significantly decreased in patients. This study provides insights into the instant brain effects involving the thalamus-related functional connectivity of taVNS performed on insomnia disorder patients.

The thalamic clustering coefficient moderates the vigor-sleep quality relationship

Sleep disorders affect more than one-quarter of the world's population, resulting in reduced daytime productivity, impaired immune function, and an increased risk of cardiovascular disease. It is important to identify the physiological and psychological factors related to sleep for the prevention and treatment of sleep disorders. In this study, we correlated measurements of emotional state, sleep quality, and some brain neural activity parameters to better understand the brain and psychological factors related to sleep. Resting-state functional magnetic resonance imaging (rs-fMRI) of 116 healthy undergraduates were analyzed using graph theory to assess regional topological characteristics. Among these, the left thalamic cluster coefficient proved to be the ablest to reflect the characteristics of the sleep neural graph index. The Profile of Mood States (POMS) was used to measure vigor, and the Pittsburgh Sleep Quality Index (PSQI) to assess sleep quality. The results showed that the left thalamic clustering coefficient was negatively correlated with sleep quality and vigor. Further, the left thalamic clustering coefficient moderated the relationship between vigor and sleep quality. When the left thalamic clustering coefficient was very low, there was a significant positive correlation between vigor and sleep quality. However, when the left thalamic clustering coefficient was high, the correlation between vigor and sleep quality became insignificant. The relationship between vigor and sleep quality is heterogeneous. Analyzing the function of the left thalamic neural network could help understand the variation in the relationship between vigor and sleep quality in different populations. Such observations may help in the development of personalized interventions for sleep disorders.

A voxel-based morphometry investigation of brain structure variations in late-life depression with insomnia

Background

Late-life depression (LLD) is linked to various medical conditions and influenced by aging-related processes. Sleep disturbances and insomnia symptoms may be early indicators or risk factors for depression. Neuroimaging studies have attempted to understand the neural mechanisms underlying LLD, focusing on different brain networks. This study aims to further delineate discriminative brain structural profiles for LLD with insomnia using MRI.

Methods

We analyzed 24 cases in the LLD with insomnia group, 26 cases in the LLD group, and 26 in the healthy control (HC) group. Patients were evaluated using the Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA), Mini-Mental State Examination (MMSE), and Pittsburgh Sleep Quality Index (PSQI). Structural MRI data were gathered and analyzed using voxel-based morphometry (VBM) to identify differences in gray matter volume (GMV) among the groups. Correlation analyses were conducted to explore the relationships between GMV and clinical characteristics.

Results

Significant difference in sex distribution was observed across the groups (p = 0.029). However, no significant differences were detected in age and MMSE scores among the groups. LLD with insomnia group exhibited significantly higher HAMA (p = 0.041) and PSQI scores (p < 0.05) compared to the LLD group. ANOVA identified significant difference in GMV of anterior lobe of cerebellum (peak MNI coordinate: x = 52, y = -40, z = -30) among HC, LLD, and LLD with insomnia. Post-hoc two-sample t-tests revealed that the significant difference in GMV was only found between the LLD group and the HC group (p < 0.05). The mean GMV in the cerebellum was positively correlated with HAMA scale in LLD patients (r = 0.47, p < 0.05).

Conclusion

There is significant difference in GMV in the LLD group, the association between late-life depression and insomnia may be linked to anxiety. This study provides insights into the discriminative brain structural profiles of LLD and LLD with insomnia, advancing the understanding of the underlying neural mechanisms and potential targets for intervention.

Predicting insomnia severity using structure-function coupling in female chronic insomnia patients

Functional connectivity between brain regions is constrained by the underlying structural pathways. However, how this structure-function coupling is disrupted in female patients with insomnia disorder is unclear. This study examines if the whole-brain pattern of structure-function coupling could be used to predict unseen female patients' insomnia severity index. Resting-state functional MRI and diffusion-weighted imaging were performed in 82 female participants with chronic insomnia. Structure-function coupling was computed using the Spearman rank correlations between structural and functional connectivity profiles. Using relevance vector regression approach and 10-fold cross-validation, we predicted the individuals' insomnia severity index using the pattern of whole-brain structure-function coupling. Finally, we extracted the contribution of each regional coupling to the prediction model. The pattern of structure-function coupling could be used to significantly predict unseen individuals' insomnia severity index scores (r = 0.29, permutation P < 0.001; mean absolute error (MAE) = 4.59, permutation P < 0.001). Moreover, the brain regions with high functional hierarchy, including regions in the default mode network, mainly displayed negative contribution weights, while the regions with lower functional hierarchy, including occipital regions and the precentral gyrus, mainly displayed positive contribution weights. This is the first study to demonstrate an association between structure-function coupling and the insomnia severity index in females with insomnia disorder. Importantly, our data suggest that insomnia severity is associated with a reduction in structure-function coupling in higher-order brain regions and an increase in structure-function coupling in lower-order brain regions.

Assessing the effect of interaction between lifestyle and longitudinal changes in brain structure on sleep phenotypes

Longitudinal changes in brain structure and lifestyle can affect sleep phenotypes. However, the influence of the interaction between longitudinal changes in brain structure and lifestyle on sleep phenotypes remains unclear. Genome-wide association study dataset of longitudinal changes in brain structure was obtained from published study. Phenotypic data of lifestyles and sleep phenotypes were obtained from UK Biobank cohort. Using genotype data from UK Biobank, we calculated polygenetic risk scores of longitudinal changes in brain structure phenotypes. Linear/logistic regression analysis was conducted to evaluate interactions between longitudinal changes in brain structure and lifestyles on sleep duration, chronotype, insomnia, snoring and daytime dozing. Multiple lifestyle × longitudinal changes in brain structure interactions were detected for 5 sleep phenotypes, such as physical activity×caudate_age2 for daytime dozing (OR = 1.0389, P = 8.84 × 10-3) in total samples, coffee intake×cerebellar white matter volume_age2 for daytime dozing (OR = 0.9652, P = 1.13 × 10-4) in females. Besides, we found 4 overlapping interactions in different sleep phenotypes. We conducted sex stratification analysis and identified one overlapping interaction between female and male. Our results support the moderate effects of interaction between lifestyle and longitudinal changes in brain structure on sleep phenotypes, and deepen our understanding of the pathogenesis of sleep disorders.

Enhanced intrathalamic morphological connectivity in patients with chronic insomnia

This study aimed to systematically investigate abnormal morphological connectivity in subregions of the thalamus and examine the clinical relevance of this connectivity in patients with chronic insomnia. One hundred and two patients with chronic insomnia (aged 45.50 [34.75 ~ 58.00] years; 24 men, 78 women) and one hundred and one healthy controls (aged 45.00 [34.00 ~ 55.00] years; 32 men, 69 women) were recruited. Intrathalamic and thalamocortical morphological connectivity in the thalamic subregions defined in the Human Brainnetome Atlas were computed and compared between the two groups. Spearman's correlation was used to estimate the association between thalamic morphological connectivity alterations and clinical variables. Compared with the control group, the insomnia group exhibited higher intrathalamic mean morphological connectivity than the control group, though no alterations in thalamocortical morphological connectivity were observed. However, no correlation was found between altered intrathalamic morphological connectivity and behavioral scales. In addition, alterations in morphological connectivity among thalamic subregions were found mainly in the left medial premotor thalamus, left medial prefrontal thalamus, and left sensory thalamus; however, these results were no longer significant after correction. Our findings suggest increased intrathalamic morphological connectivity in patients with chronic insomnia, thus enriching the understanding of morphological connectivity at the individual level and providing new perspectives for clinical interventions and diagnostic imaging.

Abnormal amygdala functional connectivity in MDD patients with insomnia complaints

BACKGROUND

Insomnia is one of the major symptom relevant factors in major depressive disorder (MDD), but the neurological mechanisms underlying the multiple effect between insomnia and depression have not been well interpreted. This study aimed at exploring the potential mechanisms between insomnia and depression based on amygdala-based resting-state functional connectivity (RSFC).

METHODS

In total 56 MDD patients with low insomnia (MDD-LI) patients, 46 MDD patients with high insomnia (MDD-HI) patients, and 57 healthy controls (HCs) were employed and underwent a resting-state functional magnetic resonance imaging (fMRI) scan. ANOVA test was performed on RSFC value for three groups. Correlation analysis was conducted to evaluate the relationship between abnormal RSFC values and clinical features.

RESULTS

We found that MDD-HI mainly showed increased RSFC in (bilateral superior temporal gyrus (STG), and decreased RSFC in left supplementary motor area (SMA) and bilateral postcentral gyrus (PoCG) compared with MDD-LI. Correlation analysis indicated that RSFC of the bilateral amygdala with STG were positively associated with the sleep disturbance score and adjust HAMD score.

CONCLUSION

Our findings suggest that RSFC in temporal lobe and other specifically activated regions may be associated with neural circuits involved with insomnia in MDD. These provide new evidence for understanding the potential mechanisms of major depression and insomnia from the perspective of functional connectivity.

SARS-CoV-2 infection in hamsters and humans results in lasting and unique systemic perturbations after recovery

The host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in prolonged pathologies collectively referred to as post-acute sequalae of COVID-19 (PASC) or long COVID. To better understand the mechanism underlying long COVID biology, we compared the short- and long-term systemic responses in the golden hamster after either SARS-CoV-2 or influenza A virus (IAV) infection. Results demonstrated that SARS-CoV-2 exceeded IAV in its capacity to cause permanent injury to the lung and kidney and uniquely affected the olfactory bulb (OB) and olfactory epithelium (OE). Despite a lack of detectable infectious virus, the OB and OE demonstrated myeloid and T cell activation, proinflammatory cytokine production, and an interferon response that correlated with behavioral changes extending a month after viral clearance. These sustained transcriptional changes could also be corroborated from tissue isolated from individuals who recovered from COVID-19. These data highlight a molecular mechanism for persistent COVID-19 symptomology and provide a small animal model to explore future therapeutics.

Abnormalities of the Default Mode Network Functional Connectivity in Patients with Insomnia Disorder

Objective

This paper aimed to probe changes in the default mode network (DMN) functional connectivity (DMNFC) of the brain of patients with insomnia disorder (ID) under the resting state.

Methods

A total of 67 patients with ID and 67 graphically matched healthy controls were selected. Then, their general information was collected, followed by a psychological scale valuation. Resting state functional magnetic resonance imaging (rs-fMRI) scanning was conducted. Subsequently, collected statistics were processed, bilateral precuneus and medial superior frontal gyrus were defined as regions of interest (ROI), and the difference in intensity between these two groups was compared.

Results

Compared with the healthy control group, the patients in the ID group were observed with abnormalities of DMNFC. Specifically, a significant increase in the functional connectivity (FC) could be observed between the left medial superior frontal gyrus and left central anterior gyrus, the left medial superior frontal gyrus and anterior cingulate gyrus, the right medial superior frontal gyrus and left central anterior gyrus, the left anterior cuneiform and left central anterior/posterior gyrus, the left anterior cuneiform and left superior occipital gyrus, as well as the right anterior cuneiform and left central posterior gyrus. However, the FC between the left anterior cuneiform and the right middle frontal gyrus was weakened, as well as between the left anterior cuneiform and the right angle gyrus and between the right precuneus and the left inferior temporal gyrus.

Conclusion

ID patients may suffer changes in FC. The decline of FC in DMN may be one of the underlying causes of ID; the enhancement of FC between DMN and the visual-spatial attention network may play a key role in the mechanisms of impaired brain functional networks of ID.

A Comparative Study of Regional Homogeneity of Resting-State fMRI Between the Early-Onset and Late-Onset Recurrent Depression in Adults

Background

Neurobiological mechanisms underlying the recurrence of major depressive disorder (MDD) at different ages are unclear, and this study used the regional homogeneity (ReHo) index to compare whether there are differences between early onset recurrent depression (EORD) and late onset recurrent depression (LORD).

Methods

Eighteen EORD patients, 18 LORD patients, 18 young healthy controls (HCs), and 18 older HCs were included in the rs-fMRI scans. ReHo observational metrics were used for image analysis and further correlation of differential brain regions with clinical symptoms was analyzed.

Results

ANOVA analysis revealed significant differences between the four groups in ReHo values in the prefrontal, parietal, temporal lobes, and insula. Compared with EORD, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, left middle temporal gyrus/left angular gyrus, and right middle temporal gyrus/right angular gyrus, and lower ReHo in the right inferior frontal gyrus/right insula and left superior temporal gyrus/left insula. Compared with young HCs, the EORD had higher ReHo in the right inferior frontal gyrus/right insula, left superior temporal gyrus/left insula, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the left inferior parietal lobule, right inferior parietal lobule, and left middle temporal gyrus/left angular gyrus. Compared with old HCs, the LORD had higher ReHo in the right fusiform gyrus/right middle temporal gyrus, right middle temporal gyrus/right angular gyrus, and left rolandic operculum gyrus/left superior temporal gyrus, and lower ReHo in the right inferior frontal gyrus/right insula. ReHo in the right inferior frontal gyrus/right insula of patients with LORD was negatively correlated with the severity of 17-item Hamilton Rating Scale for Depression (HAMD-17) scores (r = −0.5778, p = 0.0120).

Conclusion

Adult EORD and LORD patients of different ages have abnormal neuronal functional activity in some brain regions, with differences closely related to the default mode network (DMN) and the salience network (SN), and patients of each age group exhibit ReHo abnormalities relative to matched HCs.

Clinical Trial Registration

[http://www.chictr.org.cn/], [ChiCTR1800014277].

Reduced left lateralized functional connectivity of the thalamic subregions between short-term and chronic insomnia disorder

The purpose of the study was to systematically investigate the structural and functional abnormalities in the subregions of the thalamus and to examine their clinical relevance in patients with short-term and chronic insomnia disorder (ID). Thirty-four patients with short-term ID, 41 patients with chronic ID, and 46 healthy controls (HCs) were recruited. Grey matter volume and seed-based resting-state functional connectivity (RSFC) were compared for each thalamic subregion (bilateral cTtha, lPFtha, mPFtha, mPMtha, Otha, Pptha, rTtha, and Stha) between the three groups. Spearman's correlation was used to estimate the associations between thalamic alterations and clinical variables. Compared with the HCs and chronic ID group, the short-term ID group exhibited lower RSFC of the left cTtha, lPFtha, Otha and Pptha with the bilateral caudate. In addition, the short-term ID group exhibited lower RSFC between the left mPFtha and left caudate in comparison with the other two groups. Convergent RSFC alterations were found in the left cTtha and Otha with the right parahippocampal gyrus in both ID groups. Moreover, a positive correlation was found for the left Otha-caudate RSFC with the Epworth sleepiness scale scores (r = 0.340, P = 0.040). Our findings suggest shared and unique RSFC alterations of certain thalamic subregions with paralimbic regions between short-term and chronic ID. These findings have implications for understanding common and specific pathophysiology of different types of ID.

Multimodal investigation of the association between shift work and the brain in a population-based sample of older adults

Neuropsychological studies reported that shift workers show reduced cognitive performance and circadian dysfunctions which may impact structural and functional brain networks. Here we tested the hypothesis whether night shift work is associated with resting-state functional connectivity (RSFC), cortical thickness and gray matter volume in participants of the 1000BRAINS study for whom information on night shift work and imaging data were available. 13 PRESENT and 89 FORMER night shift workers as well as 430 control participants who had never worked in shift (NEVER) met these criteria and were included in our study. No associations between night shift work, three graph-theoretical measures of RSFC of 7 functional brain networks and brain morphology were found after multiple comparison correction. Preceding multiple comparison correction, our results hinted at an association between more years of shift work and higher segregation of the visual network in PRESENT shift workers and between shift work experience and lower gray matter volume of the left thalamus. Extensive neuropsychological investigations supplementing objective imaging methodology did not reveal an association between night shift work and cognition after multiple comparison correction. Our pilot study suggests that night shift work does not elicit general alterations in brain networks and affects the brain only to a limited extent. These results now need to be corroborated in studies with larger numbers of participants.

Self-Reported Sleep Quality Across Age Modulates Resting-State Functional Connectivity in Limbic and Fronto-Temporo-Parietal Networks: An Exploratory Cross-Sectional fMRI Study

Sleep problems are increasingly present in the general population at any age, and they are frequently concurrent with—or predictive of—memory disturbances, anxiety, and depression. In this exploratory cross-sectional study, 54 healthy participants recruited in Naples (Italy; 23 females; mean age = 37.1 years, range = 20–68) completed the Pittsburgh Sleep Quality Index (PSQI) and a neurocognitive assessment concerning both verbal and visuospatial working memory as well as subjective measures of anxiety and depression. Then, 3T fMRI images with structural and resting-state functional sequences were acquired. A whole-brain seed-to-seed functional connectivity (FC) analysis was conducted by contrasting good (PSQI score <5) vs. bad (PSQI score ≥5) sleepers. Results highlighted FC differences in limbic and fronto-temporo-parietal brain areas. Also, bad sleepers showed an anxious/depressive behavioural phenotype and performed worse than good sleepers at visuospatial working-memory tasks. These findings may help to reveal the effects of sleep quality on daily-life cognitive functioning and further elucidate pathophysiological mechanisms of sleep disorders.

Changes in the Shape and Volume of Subcortical Structures in Patients With End-Stage Renal Disease

Introduction: End-stage renal disease (ESRD) typically causes changes in brain structure, and patients with ESRD often experience cognitive and sleep disorders. We aimed to assess the changes in the subcortical structure of patients with ESRD and how they are associated with cognitive and sleep disorders.

Methods: We involved 36 adult patients for maintenance hemodialysis and 35 age- and gender-matched control individuals. All participants underwent neuropsychological examination and 3T magnetic resonance imaging (MRI) to acquire T1 anatomical images. The laboratory blood tests were performed in all patients with ESRD close to the time of the MR examination. We used volumetric and vertex-wise shape analysis approaches to investigate the volumes of 14 subcortical structural (e.g., bilateral accumbens, amygdala, hippocampus, caudate, globus pallidus, putamen, and thalamus) abnormalities in the two groups. Analyses of partial correlations and shape correlations were performed in order to identify the associations between subcortical structure, cognition, and sleep quality in patients with ESRD.

Results: The volumetric analysis showed that compared with the healthy control group, patients with ESRD had less bilateral thalamus (left: p < 0.001; right: p < 0.001), bilateral accumbens (left: p < 0.001; right: p = 0.001), and right amygdala (p = 0.002) volumes. In the vertex-wise shape analysis, patients with ESRD had abnormal regional surface atrophy in the bilateral thalamus, right accumbens, left putamen, and bilateral caudate. Moreover, the Montreal Cognitive Assessment (MoCA) score was associated with volume reduction in the bilateral thalamus (left: Spearman ρ = 0.427, p = 0.009; right: ρ = 0.319, p = 0.018), and the Pittsburgh Sleep Quality Index (PSQI) score was associated with volume reduction in the bilateral accumbens (left: ρ = −0.546, p = 0.001; right: ρ = −0.544, p = 0.001). In vertex-wise shape correlation analysis, there was a positive significant correlation between regional shape deformations on the bilateral thalamus and MoCA score in patients with ESRD.

Conclusion: Our study suggested that patients with ESRD have subcortical structural atrophy, which is related to impaired cognitive performance and sleep disturbances. These findings may help to further understand the underlying neural mechanisms of brain changes in patients with ESRD.

Sleep discrepancy is associated with alterations in the salience network in patients with insomnia disorder: An EEG-fMRI study

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Simultaneous EEG-fMRI was used to clarify the association between the brain functional connectivity and sleep discrepancy between self-report and polysomnography in patients with insomnia disorder.

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An altered anterior insula-based connectivity across wakefulness and all NREM stages.

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Sleep discrepancy was significantly associated with anterior insula–putamen/thalamus connectivity during wakefulness.

Background

Positron emission tomography – computed tomography (PET-CT) research has shown that sleep discrepancy recorded by self-report and polysomnography (PSG) may be related to the altered metabolic rate of the anterior insula (aINS) during non-rapid eye movement (NREM) sleep in patients with insomnia disorder. We aim to explore the functional connectivity of aINS across wake and NREM sleep in the patients and to reveal the association between aINS connectivity and sleep discrepancy.

Methods

Patients with insomnia disorder (n = 33) and healthy controls (n = 31) underwent simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) during nighttime sleep, and aINS-based connectivity was calculated across wake and NREM sleep. A linear mixed-effects model was used to assess the main effect of group and group-by-stage (wake, NREM stages 1–3) interaction effect on aINS connectivity. Similar mixed models were used to assess the potential correlation between aINS connectivity and the sleep misperception index (MI).

Results

A significant group-by-stage interaction effect on aINS-based connectivity was observed in the bilateral frontal gyrus, right inferior temporal gyrus, bilateral middle occipital gyrus and right postcentral gyrus (p < 0.05, corrected). There was also a significant group-by-MI interaction effect on aINS connectivity with the putamen and thalamus during wakefulness (p < 0.05 corrected); MI was significantly associated with aINS–putamen/thalamus connectivity in the control group, whereas the association was weak or even nonsignificant in the patient group. There was no significant main effect of group.

Conclusion

The waking activity of a neural pathway containing the aINS, putamen, and thalamus may underlie sleep perception, potentially providing important perspectives to reveal complex mechanisms of sleep discrepancy between self-report and PSG.

Functional Connectivity Density in the Sensorimotor Area is Associated with Sleep Latency in Patients with Primary Insomnia

OBJECTIVE

It is unclear whether the patterns of functional connectivity density (FCD) differ between patients with primary insomnia (PI) and healthy subjects. In the present study, we investigated the features of FCD in patients with PI using resting-state functional MRI (rsfMRI).

METHODS

rsfMRI datasets of 32 patients with PI and 34 healthy controls (HCs) were obtained using a 3-Tesla scanner. FCD analysis was performed to compare voxels with abnormal whole-brain functional connectivity with other voxels among patients with PI and HCs. Abnormal brain regions were then used as seed points for FC analysis.

RESULTS

Compared with HCs, patients with PI exhibited significantly decreased FCD in the left medial frontal gyrus and increased FCD in the left supplementary motor area (SMA). With the left medial frontal gyrus as the seed point, patients with PI showed decreased FC between the left medial frontal gyrus and the left fusiform gyrus compared with HCs. With the left SMA as the seed point, patients with PI exhibited increased FC between the left SMA and the right anterior cingulate gyrus. Correlation analysis revealed that the increased FCD values in the left SMA were positively correlated with sleep latency in patients with PI.

CONCLUSION

Default-mode network and SMA dysfunctions may be related to the pathophysiology of PI.

Thalamocortical functional connectivity in patients with insomnia using resting-state fMRI

BACKGROUND

Insomnia is a common disorder that affects a vast number of patients; the hyperarousal theory of insomnia postulates that patients with insomnia are physiologically activated not only at nighttime but also during the daytime. We aimed to investigate the differences in the resting-state functional connectivity (RSFC) of the thalamus with cortical areas between patients with insomnia disorder and healthy controls.

METHODS

All participants completed clinical questionnaires and underwent portable polysomnography and resting-state fMRI.

RESULTS

Patients in the insomnia group (n = 50) showed increased RSFC between the thalamus and right medial superior frontal area, bilateral middle temporal areas, left rectus and right parahippocampal areas compared with controls (n = 42) after controlling for age, sex and education level. Among the pairs that showed increased connectivity, several functional connections were negatively correlated with sleep efficiency, measured by polysomnography.Limitations: We used a small sample size.

CONCLUSION

We consider these results on increased thalamocortical hyperactivity in brain areas related to sensory functions as providing evidence for the hyperarousal theory of insomnia.

Functional connectivity changes in insomnia disorder: A systematic review

Insomnia (ID) is the most common sleep disorder; however pathogenetic mechanisms underlying ID symptoms are not fully understood. Adopting a multifactorial view and considering ID a condition that involves interregional neuronal coordination would be useful to understand the ID pathophysiology. Functional connectivity (FC) may help to shed light on functional processes and neural correlates underlying ID symptoms. Despite a growing number of studies assessing FC anomalies, insight into ID pathophysiology is still fragmentary. This systematic review aims to search empirical evidence regarding FC changes in ID during resting-state. Thirty-one studies involving 1052 ID participants met the inclusion criteria for this review. Results suggested several associations between ID symptoms and impaired intra- and inter-hemispheric interactions of principal resting-state networks. Overall, evidence supported the hypothesis that a disrupted organization of the brain functional connectome characterizes ID, resulting in a decline in sleep, cognition, emotion, and memory. However, the wide methodological heterogeneity between reviewed studies and limitations in terms of study protocols and statistical approaches raised from this systematic review, makes it difficult to provide a univocal framework of ID pathophysiology. Future researches in this field should lead towards shared and rigorous search designs to ensure solid research evidence in the ID pathophysiology.

Abnormal functional connectivity of the salience network in insomnia

The salience network plays an important role in detecting stimuli related to behavior and integrating neural processes. The aim of this study was to investigate changes in functional connectivity of the salience network in insomnia patients. Independent component analysis combined with a dual regression approach was used to examine functional connectivity differences in the salience network between patients with insomnia (n = 33) and healthy controls (n = 33). Pearson correlation analysis was used to analyze the relationship between differences in functional connectivity and the clinical characteristics of insomnia patients. Compared to healthy controls, insomnia patients showed increased functional connectivity in the dorsal anterior cingulate cortex within the salience network, as well as greater connectivity between the salience network and other brain regions including the dorsolateral prefrontal cortex, superior frontal gyrus, sensorimotor area and brain stem. The correlation analysis showed that increased functional connectivity between the salience network and left dorsolateral prefrontal cortex was positively correlated with Pittsburgh Sleep Quality Index score. Increased functional connectivity between salience network and several brain regions may be related to hyperarousal in insomnia patients. The connectivity between salience network and dorsolateral prefrontal cortex may potentially be used as a neuroimaging biomarker of sleep quality.

Specific cortical and subcortical grey matter regions are associated with insomnia severity

Background

There is an increasing awareness that sleep disturbances are a risk factor for dementia. Prior case-control studies suggested that brain grey matter (GM) changes involving cortical (i.e, prefrontal areas) and subcortical structures (i.e, putamen, thalamus) could be associated with insomnia status. However, it remains unclear whether there is a gradient association between these regions and the severity of insomnia in older adults who could be at risk for dementia. Since depressive symptoms and sleep apnea can both feature insomnia-related factors, can impact brain health and are frequently present in older populations, it is important to include them when studying insomnia. Therefore, our goal was to investigate GM changes associated with insomnia severity in a cohort of healthy older adults, taking into account the potential effect of depression and sleep apnea as well. We hypothesized that insomnia severity is correlated with 1) cortical regions responsible for regulation of sleep and emotion, such as the orbitofrontal cortex and, 2) subcortical regions, such as the putamen.

Methods

120 healthy subjects (age 74.8±5.7 years old, 55.7% female) were recruited from the Hillblom Healthy Aging Network at the Memory and Aging Center, UCSF. All participants were determined to be cognitively healthy following a neurological evaluation, neuropsychological assessment and informant interview. Participants had a 3T brain MRI and completed the Insomnia Severity Index (ISI), Geriatric Depression Scale (GDS) and Berlin Sleep Questionnaire (BA) to assess sleep apnea. Cortical thickness (CTh) and subcortical volumes were obtained by the CAT12 toolbox within SPM12. We studied the correlation of CTh and subcortical volumes with ISI using multiple regressions adjusted by age, sex, handedness and MRI scan type. Additional models adjusting by GDS and BA were also performed.

Results

ISI and GDS were predominantly mild (4.9±4.2 and 2.5±2.9, respectively) and BA was mostly low risk (80%). Higher ISI correlated with lower CTh of the right orbitofrontal, right superior and caudal middle frontal areas, right temporo-parietal junction and left anterior cingulate cortex (p<0.001, uncorrected FWE). When adjusting by GDS, right ventral orbitofrontal and temporo-parietal junction remained significant, and left insula became significant (p<0.001, uncorrected FWE). Conversely, BA showed no effect. The results were no longer significant following FWE multiple comparisons. Regarding subcortical areas, higher putamen volumes were associated with higher ISI (p<0.01).

Conclusions

Our findings highlight a relationship between insomnia severity and brain health, even with relatively mild insomnia, and independent of depression and likelihood of sleep apnea. The results extend the previous literature showing the association of specific GM areas (i.e, orbitofrontal, insular and temporo-parietal junction) not just with the presence of insomnia, but across the spectrum of severity itself. Moreover, our results suggest subcortical structures (i.e., putamen) are involved as well. Longitudinal studies are needed to clarify how these insomnia-related brain changes in healthy subjects align with an increased risk of dementia.

White matter microstructural abnormalities in primary insomnia: A systematic review of diffusion tensor imaging studies

Primary insomnia (PI), the most common sleep disorder, is primarily characterized by difficulties in initiating and maintaining sleep and deficits in daytime functioning. Study of white matter (WM) connections of the brain might provide valuable information regarding the underlying neural mechanism of PI. Diffusion tensor imaging (DTI) provides non-invasive access to the microstructural and network properties of brain WM, and thus, a great opportunity to quantitatively and sensitively study the human brain. The current literature of PI does not provide a consistent explanation of the etiology and pathology of the disorder; thus, we searched PubMed, EMBASE, and SCOPUS for DTI studies that compared WM integrity or network organization between PI patients and healthy controls to integrate all existing literature as an insight for further studies, and, hopefully, effective prevention and management of the disorder. English peer-reviewed full-text publications that investigated the diffusion indices of PI patients or those with insomnia symptoms compared with a group of healthy controls were included. We included 11 studies and extracted the data for qualitative synthesis. Except for one study, all studies were rated as high-quality, based on quality assessment. In aggregation, a total of 541 patients with PI and 679 healthy controls were included in this study. Our review of DTI studies suggests that WM disruptions in PI are better characterized in the context of neural networks. Frontostriatal, frontothalamic, and corticocortiscal networks, as well as the limbic system, seem to be the main neural networks with microstructural and network alterations in patients with PI. To illustrate, different parts of corona radiate and internal capsule within the corticosubcortical networks and superior longitudinal fasciculus within the corticocortical networks showed altered microstructural properties in PI patients. In view of the fact that the findings from individual studies are heterogeneous, it is difficult to derive consistent findings from the results, and the divergence of the findings must not be disregarded. Thus, this study is a starting point for future studies, and its implications for etiology and pathogenesis of insomnia should be regarded cautiously.

Relation of Decreased Functional Connectivity Between Left Thalamus and Left Inferior Frontal Gyrus to Emotion Changes Following Acute Sleep Deprivation

Objective: The thalamus is a key node for sleep-wake pathway gate switching during acute sleep deprivation (ASD), and studies have shown that it plays a certain role in emotion changes. However, there are no studies on the association between the thalamus and emotion changes in ASD. In this study, we used resting-state functional magnetic resonance imaging (R-fMRI) to explore whether changes in the functional connections between the thalamus and other brain regions are related to emotion changes and further explored the function of the thalamus under total ASD conditions.

Method: Thirty healthy, right-handed adult men underwent emotional assessment according to the Profile of Mood States Scale and R-fMRI scans before and after ASD. The correlations between changes in functional connectivity between the thalamus and other brain regions and emotion changes were then studied.

Results: Positive emotions and psychomotor performance were reduced, and negative emotions were increased following ASD. The functional connections between the left thalamus and left middle temporal gyrus, left inferior frontal gyrus, right thalamus, right inferior temporal gyrus, left middle temporal pole gyrus, right calcarine, left cuneus, left rectus and left medial superior frontal gyrus were significantly altered. Decreased functional connectivity between left thalamus and left inferior frontal gyrus related to emotion changes following ASD.

Conclusion: This study finds that functional changes in the thalamus are associated with emotion changes during ASD, suggesting that the left thalamus probably plays an essential role in emotion changes under ASD conditions.

Novel Neuroimaging Biomarker for Sleep Quality in Insomnia Disorder: A Hypothalamus Resting State Study

Despite striking progress in the understanding of the neurobiology of insomnia disorder (ID), about 40% of ID patients do not reach sustained remission with the primary treatments. It is necessary to reveal novel neuroimaging biomarkers for sleep quality in ID. The hypothalamus has a central role in sleep-wake regulation by communicating with different brain regions. However, the functional implications of hypothalamus circuitry with other brain areas remains largely unknown in ID. It may be speculated that dysfunctional circuitry in the hypothalamus is involved in the pathogenesis of ID. Thus, we investigated the different network organizations of the bilateral hypothalamus during the resting-state between 26 ID patients and 28 healthy controls (HC). Correlation analysis has been carried out to link the neuroimaging findings and Pittsburgh sleep quality index (PSQI) scores. Group comparisons reveal that the resting-state functional connectivity (RSFC) between the left hypothalamic region and a few other brain regions, including the medial prefrontal cortex (mPFC) and pallidum, are significantly higher in ID compared with HC. The right inferior temporal cortex showed reduced RSFC with the left hypothalamus. No significantly different RSFC between ID and HC was detected for the right hypothalamus. Positive correlations with PSQI scores were observed for RSFC strength between the left hypothalamus and bilateral mPFC (left: r = 0.2985, p = 0.0393; right: r = 0.3723, p = 0.0056). Similarly, the RSFC strength between the right hypothalamus and bilateral mPFC (left: r = 0.3980, p = 0.0029; right: r = 0.2972, p = 0.0291) also showed significant positive correlations with PSQI scores. In conclusion, we reveal a novel neuroimaging biomarker for sleep quality, i.e., the RSFC strength of the hypothalamus-mPFC pathway. Consistent with the hyperarousal model of ID, our results shed new insights into the implications of the hyper-connection within hypothalamus circuits in the pathology of the ID.

Alterations of Subcortical Brain Structures in Paradoxical and Psychophysiological Insomnia Disorder

Insomnia disorder (ID) is a common illness associated with mood and cognitive impairments. Subtyping ID is an ongoing debate in sleep medicine, but the underlying mechanisms of each subtype is poorly understood. Growing evidence suggests that subcortical brain structures play the key roles in pathophysiology of ID and its subtypes. Here, we aimed to investigate structural alteration of subcortical regions in patients with two common ID subtypes i.e., paradoxical and psychophysiological insomnia. Fifty-five patients and 49 healthy controls were recruited for this study and T1-weighted images and subjective and objective sleep parameters (i.e., Pittsburgh Sleep Quality Index and polysomnography) were collected from participants. Subcortical structures including the hippocampus, amygdala, caudate, putamen, globus pallidus, nucleus accumbens, and thalamus were automatically segmented in FSL. Volume and shape (using surface vertices) of each structure were compared between the groups, controlled for covariates, and corrected for multiple comparisons. In addition, correlations of sleep parameters and surface vertices or volumes were calculated. The caudate's volume was smaller in patients than controls. Compared with controls, we found regional shrinkage in the caudate, nucleus accumbens, posterior putamen, hippocampus, thalamus, and amygdala in paradoxical insomnia and shrinkage in the amygdala, caudate, hippocampus, and putamen in psychophysiological insomnia. Interestingly, comparing two patients groups, shape alteration in the caudate, putamen, and nucleus accumbens in paradoxical insomnia and shrinkage in the thalamus, amygdala, and hippocampus in psychophysiological insomnia were observed. Both subjective and objective sleep parameters were associated with these regional shape alterations in patients. Our results support the differential role of subcortical brain structures in pathophysiology of paradoxical and psychophysiological insomnia.

Brain structural correlates of insomnia severity in 1053 individuals with major depressive disorder: results from the ENIGMA MDD Working Group

It has been difficult to find robust brain structural correlates of the overall severity of major depressive disorder (MDD). We hypothesized that specific symptoms may better reveal correlates and investigated this for the severity of insomnia, both a key symptom and a modifiable major risk factor of MDD. Cortical thickness, surface area and subcortical volumes were assessed from T1-weighted brain magnetic resonance imaging (MRI) scans of 1053 MDD patients (age range 13-79 years) from 15 cohorts within the ENIGMA MDD Working Group. Insomnia severity was measured by summing the insomnia items of the Hamilton Depression Rating Scale (HDRS). Symptom specificity was evaluated with correlates of overall depression severity. Disease specificity was evaluated in two independent samples comprising 2108 healthy controls, and in 260 clinical controls with bipolar disorder. Results showed that MDD patients with more severe insomnia had a smaller cortical surface area, mostly driven by the right insula, left inferior frontal gyrus pars triangularis, left frontal pole, right superior parietal cortex, right medial orbitofrontal cortex, and right supramarginal gyrus. Associations were specific for insomnia severity, and were not found for overall depression severity. Associations were also specific to MDD; healthy controls and clinical controls showed differential insomnia severity association profiles. The findings indicate that MDD patients with more severe insomnia show smaller surfaces in several frontoparietal cortical areas. While explained variance remains small, symptom-specific associations could bring us closer to clues on underlying biological phenomena of MDD.

Functional Connectivity Abnormalities of Brain Regions With Structural Deficits in Primary Insomnia Patients

OBJECTIVES

The present study examined the abnormal resting state functional connections (RSFCs) in structural deficit brain regions of primary insomnia (PI) patients.

METHODS

Thirty-three PI patients and 38 well-matched healthy controls participated in our study. We used voxel-based morphometry and RSFC to study functional connectivity abnormalities of brain regions with structural deficits in PI patients.

RESULTS

PI patients showed decreased gray matter (GM) volume in the left dorsolateral prefrontal cortex, left orbitofrontal cortex (OFC), bilateral middle frontal gyrus (MFC), right inferior frontal gyrus (IFG), and left inferior temporal gyrus. Gray matter volume in the right MFC negatively correlated with Self-Rating Scale of Sleep (SRSS) scores, and GM volume in the right IFG negatively correlated with SRSS and Insomnia Severity Index (ISI) scores. Therefore, the right MFC and right IFG were selected as regions of interest for RSFC analysis. PI patients had weakened RSFC between the right inferior parietal gyrus (IPC) and the right MFC compared to the healthy controls and between the left OFC and right IFG. The RSFC between the right MFC and right IPC negatively correlated with SRSS scores. The RSFC between the right IFG and left OFC negatively correlated with SRSS, ISI, SAS, and SDS scores.

CONCLUSIONS

The present study found structural changes in the right MFC and right IFG accompanied by RSFC changes. This finding may provide novel insights into the neural mechanisms of PI via combining structural and functional modality information.

Right arcuate fasciculus and superior longitudinal fasciculus abnormalities in primary insomnia

Primary insomnia (PI) is a very common phenomenon and associated with functional impairments of attention, memory and mood regulation. However, its neurobiology is poorly understood. To date, the studies about integrity of white matter (WM) tracts in PI patients have been still rare. In the present study, we used Automated Fiber Quantification (AFQ), which reliably and efficiently quantified diffusion measurements at multiple locations along the WM trajectory based on diffusion tensor imaging (DTI), to assess WM diffusion properties differences between 23 PI patients and 32 matched healthy controls in 18 tracts. The relationships between neuroimaging differences and sleep behaviors were explored, including Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index Scale (ISI). Compared with healthy control group, right arcuate fasciculus (Arc) and superior longitudinal fasciculus (SLF) showed significant higher fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD) along tract length in PI patients (FWE corrected, p < 0.01). Axial diffusivity (AD) for PI patients was higher in right Arc and lower in right SLF. Correlation analyses revealed that FA of right Arc and MD of right SLF were negatively correlated with PSQI score in PI patients, and AD of right Arc and FA of right SLF were positively correlated with PSQI score. Negative correlation was observed between FA of right Arc and AD of right SLF and ISI score in PI patients. Our findings can help us to improve the understanding of the neural mechanisms of primary insomnia at abnormalities in WM microstructure.

Reduced resting-state functional connectivity and sleep impairment in abstinent male alcohol-dependent patients

Alcohol dependence is associated with poor sleep quality, which has both been implicated with thalamocortical circuits function. To identify the possible roles of these circuits in the alcohol-sleep association, we investigated the volume of both left and right thalamus and corresponding resting-state functional connectivity (RSFC) differences between 15 alcohol-dependent patients (AD) and 15 healthy controls (HC) male participants. The neuroimaging findings were then correlated with clinical variables, that is, Alcohol Use Disorders Identification Test (AUDIT) and Pittsburgh Sleep Quality Index (PSQI). Additionally, mediation analysis was carried out to test whether the thalamocortical RSFC mediates the relationship between drinking behavior and sleep impairments in AD when applicable. We observed a significant positive correlation between AUDIT score and PSQI score in AD. Compared with HC, AD showed reduced RSFC between the left thalamus and medial prefrontal cortex (mPFC), orbitofrontal cortex, anterior cingulate cortex (ACC), and right caudate. We also observed a negative correlation between RSFC of the left thalamus-mPFC and PSQI score in AD. More importantly, the left thalamus-mPFC RSFC strength mediated the relationship between AUDIT score and PSQI score in AD. No significant difference was detected in the normalized volume of both left and right thalamus, and volumes were not significantly correlated with clinical variables. Our results demonstrate that AD show abnormal interactions within thalamocortical circuits in association with drinking behaviors and sleep impairments. It is hoped that our study focusing on thalamocortical circuits could provide new information on potential novel therapeutic targets for treatment of sleep impairment in alcohol-dependent patients.