Reduced structural connectivity in Insomnia Disorder

Abstract

Insomnia Disorder is the most prevalent sleep disorder, and it involves both sleep difficulties and daytime complaints. The neural underpinnings of Insomnia Disorder are poorly understood. Several existing neuroimaging studies focused on local measures and specific regions of interests, which makes it difficult to judge their whole‐brain significance. We therefore here applied a data‐driven approach to assess differences in whole‐brain structural connectivity between adults with Insomnia Disorder and matched controls without sleep complaints. We used diffusion tensor imaging and probabilistic tractography to assess whole‐brain structural connectivity, and examined group differences using network‐based statistics. The results revealed a significant difference in the structural connectivity of the two groups (p = .014). Participants with Insomnia Disorder showed reduced connectivity in a sub‐network that included mainly fronto‐subcortical connections with the insula as a key region. By taking a whole‐brain network perspective, our study enables the integration of previous inconsistent findings. Our results reveal that reduced structural connectivity of the left insula and the connections between frontal and subcortical regions are central neurobiological features of Insomnia Disorder. The importance of these areas for interoception, emotional processing, stress responses and the generation of slow‐wave sleep may help guide the development of neurobiology‐based models of the prevalent condition of Insomnia Disorder.

Dissociated brain functional connectivity of fast versus slow frequencies underlying individual differences in fluid intelligence: a DTI and MEG study

“…Finally, our analyses returned a different organization of the brain subnetworks in high versus average G f . As expected, overall, these subnetworks grouped together brain regions within frontal and temporo-occipital lobes, independently for the two hemispheres and coherently with previous literature 42 , 43 , 46 . Notably, the assignment of the cingulate gyrus to a brain subnetwork differed between high and average G f , highlighting the structural and functional integration of such brain area within frontal subnetworks of the brain in high G f s. Conversely, in the average G f the cingulate was segregated in an independent module for the structural connectivity and less connected to the frontal subnetworks for the functional connectivity.…”

“…After assessing that the computation of our structural and functional connectivity matrices (illustrated in Fig. 2 ) returned results coherent with previous literature 42 – 46 , we investigated them in relation to G f.…”

“…Independently for each participant, we reconstructed the sources of the MEG signal by combining the MEG with the structural T1 MRI data in automated anatomical labelling (AAL) 43 – 45 , 47 space and estimated the functional connectivity between each pair of non-cerebellar brain areas of AAL. Similarly, we computed individual structural connectivity matrices in AAL space 42 , 46 based on the DTI images.…”

<p>Astroglial Mechanisms Underlying Chronic Insomnia Disorder: A Clinical Study</p>

“…29 The questionnaire contained 17 terms, and the total scores ranged from 0 to 52, where higher scores indicate greater depressive severity. In China, the corresponding grades to depressive states are as follows: no depression (0-7), mild depression (8)(9)(10)(11)(12)(13)(14)(15)(16)(17), moderate depression (18)(19)(20)(21)(22)(23), and severe depression .…”

“…11 In addition, diffusion tensor imaging has been used to evaluate differences in white matter tracts between insomniacs and matched controls. 12 Insomnia-related alterations in functional connectivity have also been investigated, but the results have been relatively inconsistent so far. [13][14][15] In summary, most studies on brain structure have evaluated insomnia-related differences in specific regions, but neuroimaging studies have not been able to clearly conclude what kind of damage insomnia causes and in which areas this damage occurs.…”