[Late-onset depression : Pathophysiology, diagnostics and treatment]

Bioinformatics Screening and Experimental Validation for Deciphering the Immune Signature of Late-Onset Depression

Background

Late-onset depression (LOD) is often associated with more severe cognitive impairment and a higher risk of disability and suicide. Emerging evidence suggests that immune system problems may be involved. This study aims to systematically characterize the genetic signature of LOD based on the immune landscape.

Methods

The expression profile of GSE76826 was obtained from the Gene Expression Omnibus (GEO) database to gather gene expression data for 10 LOD patients and 12 healthy controls (HC). Various analyses, such as Single-Sample Gene Set Enrichment Analysis (ssGSEA) and Weighted Gene Co-expression Network Analysis (WGCNA), were used to mine key genes closely related to LOD. ImmuCellAI helped us understand differences in the immune environment between LOD patients and controls, and we used an LOD animal model to validate the relevant immune characteristics.

Results

We found enriched immune pathways linked to LOD and adaptive immune responses. Using advanced bioinformatics techniques, we identified two key genes: apelin (APLN) and leptin (LEP), which have good diagnostic efficacy (AUC=0.925, 95% CI=1.00-0.83) for LOD. Neutrophil infiltration increased significantly in LOD, while CD8+ T lymphocytes (CD8_T) decreased. We finally constructed an animal model of LOD, validated two key genes and microglia marker genes in blood and hippocampus, and detected elevated pro-inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).

Conclusion

We identified and validated the presence of aberrant expression of APLN and LEP in LOD and described a possible immune mechanism involving increased release of IL-6 and TNF-α, leading to decreased CD8_T infiltration and increased neutrophil infiltration. Meanwhile, peripheral inflammation across the blood-brain barrier further promotes microglia activation, leading to neuronal damage.

Luteolin Enhances Choroid Plexus 5-MTHF Brain Transport to Promote Hippocampal Neurogenesis in LOD Rats

Folates, provided by food, are commonly used antidepressant synergists in late-onset depression (LOD). However, increased intake of folic acid in the elderly population might lead to the accumulation of unmetabolized folic acid in the systemic circulation, leading to enhanced deterioration of the central nervous system function. In addition, folates cannot access the brain directly because of the blood-brain barrier. Choroid plexus (CP) 5-methyltetrahydrofolate (5-MTHF) brain transport plays a critical role in regulating the cerebrospinal fluid (CSF) 5-MTHF content. Luteolin is a natural flavonoid that has antidepressant effects and is involved in the anti-folate resistance pathway. It remains unclear whether the antidepressant effects of luteolin are associated with the CP 5-MTHF brain transport. In this study, 20-21-month-old Wistar rats were exposed to the chronic unpredictable mild stress (CUMS) protocol for 6 consecutive weeks to explore the long-term effects of luteolin on behavior, 5-MTHF levels, hippocampal neurogenesis, and folate brain transport of the CP. In vitro primary hippocampal neural stem cells (NSCs) cultured in media containing 10% CSF from each group of rats and choroid plexus epithelial cells (CPECs) cultured in media containing 20 μM luteolin were treated with 100 μM corticosterone and 40 mg/ml D-galactose. We found that aged rats exposed to CUMS showed a significantly reduced sucrose preference, decreased locomotion activity in the open field test and accuracy of the Morris water maze test, increased immobility time in the forced swimming test, accelerated dysfunctional neurogenesis and neuronal loss in the dentate gyrus of LOD rats, as well as decreased CSF and hippocampus 5-MTHF levels, and zona occludens protein 1 (ZO-1), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC) protein levels. In vitro assays showed media containing 10% aged CSF or LOD+ Luteolin-CSF significantly increased the viability of CORT + D-gal-injured NSCs and alleviated dysfunctional neurogenesis and neuronal loss compared with the CORT + D-gal medium. However, media containing 10% LOD-CSF had no such effect. In the meantime, induction of CORT + D-gal significantly decreased the ZO-1, PCFT, RFC, and folate receptor alpha (FR-α) protein levels and transepithelial electrical resistance in rat CPECs. As expected, luteolin treatment was effective in improving these abnormal changes. These findings suggested that luteolin could ameliorate CUMS-induced LOD-like behaviors by enhancing the folate brain transport.

[Psychiatric polypharmacy and electroconvulsive therapy in treatment-resistant depression]

BACKGROUND

Despite its relevant medical risks, polypharmacy is common particularly among difficult to treat conditions, e.g. treatment refractory depression (TRD). According to numerous guidelines, electroconvulsive therapy (ECT) is the treatment of choice in severe and treatment-resistant major depression due to the high effectiveness; however, to date limited data are available concerning the effects of ECT on the concomitant prescription of psychiatric medication.

METHODS

For a retrospective explorative analysis of psychiatric polypharmacy (MED) in TRD, data from 58 inpatient treatments were collected. Due to depressive episodes, all patients received psychopharmacological treatment and cognitive behavioral therapy (MED group). Of the patients 29 also underwent ECT (ECT group). Using a modified drug burden index (mod-DBI), the psychiatric medication was quantified at admission (TP0), start (TP1) and termination of ECT (TP2) and discharge in the ECT group or in comparable periods in the MED group (TP3). Differences in distribution were tested with the t-test and alterations in measurements were tested by means of variance analysis (F-test).

RESULTS

Patients treated with ECT showed higher mod-DBI values at TP0, mainly due to more frequent prescription of benzodiazepines (BZD), mood stabilizers (MS) and antipsychotic drugs (AP). At the beginning of the inpatient treatment (TP0-TP1) there was an increase in BZD use (in both groups); in the ECT group MS were reduced and AP increased. In the time interval TP1-TP3, BZD (in both groups) and AP (ECT group) were again less frequently prescribed and MS (ECT and MED group) were increased again. Excluding BZD, there was a significant increase in mod-DBI in both groups, whereas the mod-DBI no longer showed significant differences at TP2 and TP3.

CONCLUSION

The data possibly indicate that patients with TRD who receive ECT during inpatient treatment already have a more extensive psychiatric medication at admission. Also, psychiatric medication appears to be increased less prominently when ECT is performed. These findings and the possibly associated long-term benefits should be addressed in future research.

[Psychotherapy of depressive disorders: Evidence in chronic depression and comorbidities]

BACKGROUND

Psychotherapy has been shown to be an effective treatment option for depressive disorders; however, its effectiveness varies depending on patient and therapist characteristics and the individual form of the depressive disorder.

OBJECTIVES

The aim of this article is to present the current evidence for psychotherapeutic antidepressive treatments for patients with chronic and treatment-resistant depression as well as for patients with mental and somatic comorbidities.

MATERIAL AND METHODS

During the revision of the currently valid German S3- and National Disease Management Guideline (NDMG) on unipolar depression published in 2015, a comprehensive and systematic evidence search including psychotherapy for specific patient groups was conducted. The results of this search along with a systematic update are summarized.

RESULTS

Psychotherapy has been shown to be effective in reducing depressive symptoms in patients suffering from chronic and treatment-resistant depression and in patients with mental and somatic comorbidities. The evidence is insufficient particularly for patients with mental comorbidities.

CONCLUSION

Based on the current evidence and clinical expertise the NDMG recommends psychotherapy alone or in combination with pharmacotherapy to treat most of these depressive patient groups. Evidence gaps were identified, which highlight the need for further research.