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.

Convergent and divergent functional connectivityalterations of hippocampal subregions between short-term and chronic insomnia disorder

Insomnia disorder (ID) is reclassified into short-term and chronic subtypes based on recent etiological advances, however, neural mechanisms underlying the subtypes are rarely examined. In this study, we investigated gray matter volume and resting-state functional connectivity (RSFC) alterations of hippocampal subregions in short-term and chronic ID using multimodal MRI. We found convergent and divergent alterations between both ID groups in specific hippocampal subregions [right cornu ammonis 1 (CA1), subicular complex (Subc), and caudal hippocampus, (cHipp)] with prefrontal cortex [bilateral medial prefrontal cortex (MPFC), and right middle frontal gyrus] and limbic/paralimbic regions (bilateral middle cingulate cortex and left parahippocampal gyrus). Intriguingly, the RSFC of the right CA1/cHipp, particularly the intersection between these two subregions, with bilateral MPFC exhibited gradual increases from healthy controls to short-term ID and from short-term ID to chronic ID. Moreover, a negative correlation between the right CA1-left parahippocampal gyrus RSFC and Epworth Sleepiness Scale scores, and a positive correlation between the right CA1-bilateral MPFC RSFC and Insomnia Severity Index scores were found in the chronic ID group (P < 0.05). Our findings suggest convergent and divergent RSFC alterations of specific hippocampal subregions with the prefrontal cortex and limbic/paralimbic regions between short-term and chronic ID. These findings suggest that the hippocampus is a key node in establishing diagnostic and categorical biomarkers in ID and developing more effective treatment strategies.

International study of the prevalence and factors associated with insomnia in the general population

OBJECTIVES

Insomnia is a public health problem with many repercussions. It affects a significant proportion of the general population worldwide, but the estimated prevalences in different countries are difficult to compare due to the use of heterogeneous methodologies. The objectives of the study were to compare the prevalence of insomnia in the general population in different sites around the world and to identify sociodemographic and mental health associated factors, using the same tool and within a single study.

METHODS

This multicenter cross-sectional study is based on the Mental Health in the General Population survey (MHPG). It included several sites in France and 12 countries around the world with a representative sampling of the general population. The prevalence of short-term insomnia disorder was estimated by the occurrence within one month of at least one symptom, at a minimum frequency of three per week, with repercussions on everyday life.

RESULTS

Out of the 57,298 participants, 11.3% had a diagnosis of short-term insomnia disorder, with significant differences in prevalence between sites, ranging from 2.3% to 25.5%. Insomnia was significantly related to having mood disorders, anxiety disorders, substance use disorders and psychotic disorders. Insomnia was also more common among women, older adults, working participants and those who practice a religion.

CONCLUSIONS

The prevalence of insomnia was highly variable between sites, but the predictors appeared to be the same everywhere. Insomnia seemed to be more related to the presence of mood and anxiety disorders than a site-specific effect and thus may be a good indicator of mental health.