Subtypes of insomnia revealed by the heterogeneity of neuroanatomical patterns: a structural MRI study

Subtypes of Insomnia Disorder Identified by Cortical Morphometric Similarity Network

Insomnia disorder (ID) is a highly heterogeneous psychiatric disease, and the use of neuroanatomical data to objectively define biological subtypes is essential. We aimed to examine the neuroanatomical subtypes of ID by morphometric similarity network (MSN) and the association between MSN changes and specific transcriptional expression patterns. We recruited 144 IDs and 124 healthy controls (HC). We performed heterogeneity through discriminant analysis (HYDRA) and identified subtypes within the MSN strength. Differences in MSN between subtypes and HC were compared, and clinical behavioral differences were compared between subtypes. In addition, we investigated the association between MSN changes and brain gene expression in different ID subtypes using partial least squares regression to assess genetic commonalities in psychiatric disorders and further performed functional enrichment analyses. Two distinct subtypes of ID were identified, each exhibiting different MSN changes compared to HC. Furthermore, subtype 1 is characterized by objective short sleep, impaired cognitive function, and some relationships with major depressive disorder and autism spectrum disorder (ASD). In contrast, subtype 2 has normal objective sleep duration but subjectively reports poor sleep and is only related to ASD. The pathogenesis of subtype 1 may be related to genes that regulate sleep rhythms and sleep-wake cycles. In contrast, subtype 2 is more due to adverse emotion perception and regulation. Overall, these findings provide insights into the neuroanatomical subtypes of ID, elucidating the relationships between structural and molecular aspects of the relevant subtypes.

The benefit of inhibitory control training for insomnia with short sleep duration phenotype: a pilot randomized trial

BACKGROUND

Two phenotypes of insomnia disorder (ID) have been identified based on objective total sleep duration (TST): one with short sleep duration (ISSD) and another with normal sleep duration (INSD). Recent proposals suggested that insomnia with objective short-sleep duration (TST < 7 h) is associated with impaired inhibitory function, leading to a dysregulation of cortical inhibition, which may underlie its prevalence. This study investigated the status of impaired response inhibition in these two phenotypes and examined the potential different effect of response inhibition training on these two phenotypes.

METHODS

Twenty-two healthy controls (HC) and eighty-one patients with ID were recruited, with IDs further categorized into ISSD and INSD (with TST ≥ 7 h). Clinical behavior measures, including the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), Pre-sleep Arousal Scale (PSAS), objective sleep characteristics assessed by all-night sleep electroencephalography, and the accuracy of NoGo trials in the Go/NoGo task were compared among the three groups. Subsequently, within each ID phenotype, participants were divided into training and blank control sub-groups. The two training sub-groups completed Adaptive Go/NoGo training task (Through adaptive difficulty adjustment, the task trains participants' inhibitory control) 15 times over 3 weeks, and all IDs were assessed using sleep-related subjective and objective measures and Go/NoGo task before and after the intervention.

RESULTS

ISSD patients exhibited significantly longer sleep latency (p = 0.003) compared to HC, while wakefulness duration (p = 0.004) and light sleep duration (p < 0.001) were shorter than INSD. No significant differences in objective sleep characteristics were observed between INSD and HC. Following adaptive training, the ISSD training sub-group showed decreased scores in PSQI (p = 0.039) and ISI (p = 0.053) compared to their blank control sub-group. In the INSD groups, both training and blank control sub-groups demonstrated reductions in PSQI (p < 0.001), ISI (p < 0.001), and the cognitive arousal sub-dimension of the PSAS scores (p = 0.003) in the post-session test.

CONCLUSIONS

Impaired response inhibition is a characteristic of ISSD, potentially indicating dysfunctional cortical inhibition, whereas INSD pathogenesis may be related to cognitive-emotional arousal. Response inhibition training effectively alleviates sleep problems in ISSD. These findings provide new insights for developing precise intervention strategies in ID.

TRIAL REGISTRATION

The study was prospectively registered on May 30, 2024, in Chinese Clinical Trials registry (ChiCTR2400085063).

Disrupted brain functional asymmetry at rest in patients with major depressive disorder associated with sleep disturbances

Sleep disturbances (SD) are common in major depressive disorder (MDD) patients. Brain functional asymmetry is crucial for understanding MDD pathophysiology. Previous studies using the parameter of asymmetry (PAS) approach have found brain functional asymmetry disruption in MDD. However, this has not been explored in MDD patients with SD. This study examined 26 MDD patients with SD, 34 MDD patients without SD, and 34 healthy controls using resting-state functional magnetic resonance imaging scans. SD symptoms were quantified using the 17-item Hamilton Rating Scale for Depression. PAS approach was used to evaluate functional asymmetry. MDD patients with SD displayed increased PAS in the left middle frontal gyrus (MFG)/inferior frontal gyrus (IFG) and decreased PAS in the left parahippocampal gyrus (PHG) compared to MDD patients without SD. Increased PAS in the left MFG/IFG was positively correlated with SD severity, and a negative correlation was found between decreased PAS in the left PHG and SD scores in all MDD patients. Receiver operating characteristic analysis indicated that increased PAS in the left MFG/IFG and decreased PAS in the left PHG may serve as potential neuroimaging markers to differentiate MDD patients with SD from those without SD with Area Under Curve values of 0.8157 and 0.8068, respectively. These results highlighted that increased PAS in the left MFG/IFG and decreased PAS in the left PHG may be considered a prominent feature associated with SD symptoms of MDD patients, potentially serving as imaging markers to discriminate between MDD patients with and without SD.

Gene expression is associated with brain function of insomnia disorder, rather than brain structure

Previous research has found brain structural and functional abnormalities in patients with insomnia disorder (ID). However, the relationship between brain abnormalities in ID and brain gene expression is unclear. This study explored the relationship between gene expression and brain structural or functional abnormalities in ID, and we validated the reliability of the results with two independent datasets (discover dataset: healthy control (HC) = 129, ID = 264; validation dataset: HC = 160, ID = 115). Brain imaging results show that ID has abnormal resting-state spontaneous activity, regional homogeneity, and widespread gray matter volume reduction compared to HC. The association analysis results with gene expression further revealed that brain function abnormalities in ID were significantly associated with gene expression, but structural abnormalities were not. This study establishes a link between transcriptional changes and brain functional abnormalities in ID, revealing a genetic basis that may involve several biological pathways. Specifically, these pathways include hormonal regulation of the hypothalamic-pituitary-adrenal (HPA) axis, which plays a crucial role in stress response and sleep regulation; ion transport across membranes, vital for neuronal communication; and inhibitory neuronal regulation, essential for maintaining normal brain function. Furthermore, the ID-related genes are enriched for brain tissue and cortical cells, emphasizing their relevance in understanding the biological underpinnings of ID.

Response inhibition impairment related to altered frontal-striatal functional connectivity in insomnia disorder: A pilot and non-clinical study

BACKGROUND

It is not clear whether and how insomnia disorder (ID) impairs response inhibition ability. Fronto-striatal functional connectivity (FC) plays a critical role in response inhibition and is found be abnormal in patients with ID. In this study, we examined whether insomnia symptoms impair response inhibition in a large non-clinical sample and whether impaired response inhibition is related to abnormal fronto-striatal FC.

METHODS

One hundred and fifteen young ID patients and 160 age and sex-matched healthy controls (HC) underwent resting-state functional magnetic response imaging scans and performed the stop-signal task (SST). Performance of SST, Gray Matter Volumes (GMVs), and connections of brain regions related to fronto-striatal circuits was compared between groups. Further examined the association between response inhibition impairment and fronto-striatal FC.

RESULTS

The behavioral results showed that patients with ID had significantly longer stop-signal reaction time (SSRT) compared with the HC, reflecting the impaired response inhibition among IDs. Brain imaging results showed IDs had decreased GMVs of the Right Superior Frontal (SFG) and left Supplementary Motor area (SMA). Seed-based FC results showed that compared to HC, the ID showed decreased FC between left SMA and left Paracentral lobule, left SMA and right SMA, and right SFG and right Orbital Middle Frontal gyrus, and increased FC between right SFG and right putamen. Meanwhile, the FC between right SFG and putamen was positively correlated with SSRT in IDs.

CONCLUSIONS

The current study found significantly impaired response inhibition among ID and this impairment may be related to abnormal fronto-striatal FC in ID.

Elucidating Multimodal Imaging Patterns in Accelerated Brain Aging: Heterogeneity through a Discriminant Analysis Approach Using the UK Biobank Dataset

Accelerated brain aging (ABA) intricately links with age-associated neurodegenerative and neuropsychiatric diseases, emphasizing the critical need for a nuanced exploration of heterogeneous ABA patterns. This investigation leveraged data from the UK Biobank (UKB) for a comprehensive analysis, utilizing structural magnetic resonance imaging (sMRI), diffusion magnetic resonance imaging (dMRI), and resting-state functional magnetic resonance imaging (rsfMRI) from 31,621 participants. Pre-processing employed tools from the FMRIB Software Library (FSL, version 5.0.10), FreeSurfer, DTIFIT, and MELODIC, seamlessly integrated into the UKB imaging processing pipeline. The Lasso algorithm was employed for brain-age prediction, utilizing derived phenotypes obtained from brain imaging data. Subpopulations of accelerated brain aging (ABA) and resilient brain aging (RBA) were delineated based on the error between actual age and predicted brain age. The ABA subgroup comprised 1949 subjects (experimental group), while the RBA subgroup comprised 3203 subjects (control group). Semi-supervised heterogeneity through discriminant analysis (HYDRA) refined and characterized the ABA subgroups based on distinctive neuroimaging features. HYDRA systematically stratified ABA subjects into three subtypes: SubGroup 2 exhibited extensive gray-matter atrophy, distinctive white-matter patterns, and unique connectivity features, displaying lower cognitive performance; SubGroup 3 demonstrated minimal atrophy, superior cognitive performance, and higher physical activity; and SubGroup 1 occupied an intermediate position. This investigation underscores pronounced structural and functional heterogeneity in ABA, revealing three subtypes and paving the way for personalized neuroprotective treatments for age-related neurological, neuropsychiatric, and neurodegenerative diseases.