GWAS Meta-Analysis Reveals Shared Genes and Biological Pathways between Major Depressive Disorder and Insomnia

Major depressive disorder (MDD) is one of the most prevalent and disabling mental disorders worldwide. Among the symptoms of MDD, sleep disturbance such as insomnia is prominent, and the first reason patients may seek professional help. However, the underlying pathophysiology of this comorbidity is still elusive. Recently, genome-wide association studies (GWAS) have begun to unveil the genetic background of several psychiatric disorders, including MDD and insomnia. Identifying the shared genomic risk loci between comorbid psychiatric disorders could be a valuable strategy to understanding their comorbidity. This study seeks to identify the shared genes and biological pathways between MDD and insomnia based on their shared genetic variants. First, we performed a meta-analysis based on the GWAS summary statistics of MDD and insomnia obtained from Psychiatric Genomics Consortium and UK Biobank, respectively. Next, we associated shared genetic variants to genes using two gene mapping strategies: (a) positional mapping based on genomic proximity and (b) expression quantitative trait loci (eQTL) mapping based on gene expression linkage across multiple tissues. As a result, a total of 719 shared genes were identified. Over half (51%) of them are protein-coding genes. Functional enrichment analysis shows that the most enriched biological pathways are related to epigenetic modification, sensory perception, and immunologic signatures. We also identified druggable targets using a network approach. Together, these results may provide insights into understanding the genetic predisposition and underlying biological pathways of comorbid MDD and insomnia symptoms.

Comparison of venlafaxine alone versus venlafaxine plus late partial sleep deprivation therapy combination for major depressive disorder

Treatment resistance, medication non-adherence, and side effects of pharmacotherapeutics make treatment difficult in major depressive disorder. Sleep deprivation is a fast-acting and tolerable reinforcement treatment method. In this study, we investigated the effects of late partial sleep deprivation (PSD) therapy added to venlafaxine treatment on symptoms of anxiety and depression, sleep quality and treatment process. This study was conducted in a sample of 40 patients who were admitted to our inpatient psychiatric unit with a diagnosis of major depressive disorder. While the venlafaxine (Ven) group received only venlafaxine treatment, the venlafaxine+partial sleep deprivation (Ven+PSD) group underwent late partial sleep deprivation therapy three times in the first week in addition to venlafaxine treatment. The Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HAM-D), Beck Depression Inventory, Pittsburgh Sleep Quality Index, and Insomnia Severity Index (ISI) were administered to both groups at the baseline and at the end of the 1st, 4th, and 6th weeks and, additionally, Profile of Mood State (POMS) was administered to the Ven+PSD group before and after each PSD. The Ven+PSD group had lower HAM-D and HAM-A scores than the Ven group at the end of the 1st and 6th week. Both anxiety and depression subscale scores on the POMS showed a significant decrease after PSD in the Ven+PSD group. The mean venlafaxine dose (mg/d) was significantly lower in the Ven+PSD group than in the Ven group. Late partial sleep deprivation is a fast-acting and tolerable therapy in major depressive disorder.