A multidimensional astrocytic framework links serum biomarkers to depression subtypes cognition and sleep EEG

OBJECTIVE: To investigate changed levels of serum astrocytic biomarkers, including glial cell line-derived neurotrophic factor (GDNF), aldehyde dehydrogenase (ALDH) and connexin-26, and the correlations with depression subtypes, cognitive dysfunction and electroencephalogram measures in patients with depression disorder (DD). METHODS: Seventy-three patients and 46 healthy subjects (HC) were enrolled. Questionnaires, Nine Box Maze Test (NBMT) were used to assess sleep and neuropsychology. Serum biomarkers were evaluated with enzyme-linked immunosorbent assay. Partial subjects (45 DD and 10 HC) completed polysomnography. RESULTS: Compared to the HC, the patients had lower levels of GDNF, ALDH and connexin-26, and increased errors in NBMT tasks, including spatial/object working memory (SWM/OWM) and spatial/object reference memory (SRM/ORM). The connexin-26 concentration was higher in recurrent depression relative to dysthymia and bipolar depression; and GDNF concentrations was higher in the first episode depression compared to the recurrent depression and bipolar depression, with the lowest concentration in dysthymia. Partial correlation analysis for patients showed that the GDNF positively associated with N3% and power of delta wave; ALDH positively associated with MMSE score and OWM error; and connexin-26 negatively correlated with ORM and SRM errors. CONCLUSION: Depressive patients had decreased serum levels of GDNF, ALDH and CX26, with subtype-specific difference in GDNF and CX26, which were associated with impaired cognition and slow wave power of electroencephalogram.