Structural Imaging Measures of Cortical and Basal Ganglia Morphology in Insomnia

While insomnia disorder is associated with changes in the brain, results vary across studies and levels of severity; no consistent morphometric pattern has yet emerged. Prior large-scale genetic work has implicated specific cortical and subcortical regions in the pathophysiology of insomnia. The aim of the current study is to utilise surface-based morphometry tools to examine these specific regions, thereby offering new insights into the disorder from a genetically informed perspective. This study leveraged archival neuroimaging data from the University of Pittsburgh, analysing 58 individuals with DSM-IV-TR primary insomnia and 67 good sleepers. Using T1-weighted structural MRI scans, harmonised shape analysis protocols were applied for bilateral caudate, putamen and globus pallidus. In addition, cerebellar volumes, as well as anterior cingulate and rostral middle frontal cortical thickness measures were obtained. Linear models were then constructed to assess group differences in all regions, then correlation coefficients between brain values and scores from the Pittsburgh Sleep Quality Index (PSQI) from all participants were calculated. Results revealed individuals with insomnia exhibited significantly greater cortical thinning in anterior cingulate cortex, and inward shape deformation in the head of the right caudate compared to good sleepers. These findings reveal focal neurobiological abnormalities in insomnia that are in line with regions implicated in previous genetic work. The results may hold important implications for future research identifying biomarkers and mechanisms that contribute to the onset and course of insomnia in these areas.