Ceylan, Deniz

Background/Objectives: Mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BD), along with obstructive sleep apnea (OSA), are prevalent conditions that have serious effects on affected individuals and public health. These issues have received more attention recently, as research shows there are similar risk factors and they can influence each other by worsening symptoms and treatment response. However, there is still no clear understanding of the extent of this co-occurrence and the factors that influence it. Methods: A systematic review of comorbid OSA and mood disorders was conducted from EMBASE, Ovid MEDLINE, Global Health, and APA PsycINFO (1 January 2013–25 July 2025), with meta-analyses applying random-effects models in R (metafor). Heterogeneity, publication bias, subgroup effects, and meta-regression analyses were performed by assessing demographic, clinical, and study quality variables. Results: Out of 6221 screened studies, 23 articles met eligibility criteria, yielding 2,380,986 OSA patients, with 446,495 comorbid mood disorders (MDD = 446,290; BD = 205), and 5724 mood disorder patients (MDD = 1987; BD = 3737) with 450 comorbid OSA. All meta-analyses demonstrated a significant prevalence of comorbidity, accompanied by substantial heterogeneity. Meta-regression analyses identified mean age (β = 0.18, 95% CI 0.03–0.33, p = 0.02) and mean body mass index (β = −0.18, 95% CI −0.32 to −0.04, p = 0.01) as significant moderators of OSA prevalence. Conclusions: This meta-analysis indicates a high prevalence of comorbidity between OSA and mood disorders, including MDD and BD, with significant heterogeneity. Age and body mass index emerged as significant moderators of OSA prevalence, emphasizing the need for systematic screening and tailored approaches in both clinical practice and research.

Suicide is a major public health concern; nevertheless, its neurobiology remains unknown. An area of interest in suicide research is the dorsolateral prefrontal cortex (DLPFC). We aimed to identify altered proteins and potential biological pathways in the DLPFC of individuals who died by suicide employing mass spectrometry-based untargeted proteomics. Postmortem DLPFC from age-matched male suicide mood disorder cases (n = 5) and non-suicide mood disorder cases (n = 5) were compared. The proteins that differed between groups at false discovery rate (FDR) adjusted p-values (Benjamini–Hochberg–Yekutieli) <0.3 and Log2 fold change (FC) >|0.4| were considered statistically significant and were subjected to pathway analysis by Qiagen Ingenuity software. Thirty-three of the 5162 detected proteins showed significantly altered expression levels in the suicide cases and two of them after adjustment for body mass index. The top differentially expressed protein was potassium voltage-gated channel subfamily Q member 3 (KCNQ3) (Log2FC = −0.481, p = 2.10 × 10−09, FDR = 5.93 × 10−06), which also showed a trend to downregulation in Western blot (p = 0.045, Bonferroni adjusted p = 0.090). The most notably enriched pathway was the GABA receptor signaling pathway (p < 0.001). Here, we report a reduction trend of KCNQ3 levels in the DLPFC of male suicide victims with mood disorders. Further studies with a larger sample size and equal sex representation are needed.