DOI: 10.5061/dryad.4tmpg4fg7
title: Reduced gray matter volume in the default-mode network associated with insulin resistance

description: Insulin resistance may lead to structural and functional abnormalities of
 the human brain. However, the mechanism by which insulin resistance
 impairs the brain remains elusive. In this study, we used two large
 neuroimaging databases to investigate the brain regions where insulin
 resistance was associated with the gray matter volume and to examine the
 resting-state functional connectivity between these brain regions and each
 hypothalamic nucleus. Insulin resistance was associated with reduced gray
 matter volume in the regions of the default-mode and limbic networks in
 the cerebral cortex in older adults. Resting-state functional connectivity
 was prominent between these networks and the paraventricular nucleus of
 the hypothalamus, a hypothalamic interface connecting functionally with
 the cerebral cortex. Furthermore, we found a significant correlation in
 these networks between insulin resistance-related gray matter volume
 reduction and network paraventricular nucleus of the hypothalamus
 resting-state functional connectivity. These results suggest that insulin
 resistance-related gray matter volume reduction in the default-mode and
 limbic networks emerged through metabolic homeostasis mechanisms in the
 hypothalamus.
description: Data from the Bunkyo Health Study, which aimed to prevent
 diseases requiring long-term care in older people, was used in the present
 study. Of 1629 participants in the database, insulin-dependent T2DM
 patients were excluded, and then the data of 1609 without any missing data
 were analyzed. We analyzed the gray matter volumes using a VBM software
 implemented in SPM12 and insulin resistance (HOMA-IR) was calculated using
 fasting blood sampling data. We also analyzed the
 functional connectivity between the HOMA-IR-related cerebral region and
 the hypothalamic nuclei. For this analysis, we used the data of
 resting-state functional images of HCP (N = 418).
description: # Reduced gray matter volume in the default-mode network associated with
 insulin resistance **Saki Asano et al. (2023) Cerebral Cortex
 33:11225–11234, 2023.** This study investigated the association of insulin
 resistance with the gray matter volume (GMV) and resting-state functional
 connectivity (RSFC) in the human brain using a cohort dataset including
 structural images and blood samples from &gt;1000 older adults in Japan
 and the Human Connectome Project (HCP) dataset of RSFC. The Nifti file
 showing that the regional GMV reduction was negatively associated with
 homeostasis model assessment for insulin resistance (HOMA-IR) is provided.
 The Cifti files showing that the activity of hypothalamic nuclei was
 correlated with those of cerebrocortical parcels are provided. ## The
 regional GMV reduction was negatively associated with HOMA-IR We observed
 that the GMV reduction in the precuneus, superior frontal gyrus, medial
 frontal gyrus, parietal operculum, and ventromedial prefrontal cortex was
 negatively associated with HOMA-IR (Fig. 2). The file of t map:
 Fig2_Tmap.nii ## The activity of hypothalamic nuclei was correlated with
 those of cerebrocortical parcels The functional connectivity was
 calculated between the hypothalamic nuclei and cerebrocortical parcels,
 into which the entire cerebral cortex was parcellated as functional units
 (Glasser et al. 2016). The functional connectivity between the
 cerebrocortical parcels (n=360) and the PVH are shown in Fig. 4B, and that
 between the cerebrocortical parcels and each of the other four
 hypothalamic nuclei are shown in Fig. S7. The file of the correlation map
 between the PVH and the cerebrocortical parcels: mean_zmapPVH.dscalar.nii
 The file of the correlation map between the ARC and the cerebrocortical
 parcels: mean_zmapARC.dscalar.nii The file of the correlation map between
 the DMH and the cerebrocortical parcels: mean_zmapDMH.dscalar.nii The file
 of the correlation map between the VMH and the cerebrocortical parcels:
 mean_zmapVMH.dscalar.nii The file of the correlation map between the LHA
 and the cerebrocortical parcels: mean_zmapLHA.dscalar.nii ## Softwares The
 Nifti files can be opened using SPM, MRIcron, and FSL. The Cifti files can
 be opened using wb_view.