👤 Nadia Cattane

Stressful life events (SLE) are associated with an increased likelihood of developing depression. However, the underlying mechanisms and the long-lasting consequences of SLE exposure during adolescence, a critical period for physical, sexual, and behavioural maturation, are largely unknown. Recent studies suggest that they might be mediated by aberrant epigenetic mechanisms, such as alterations in DNA methylation, histone modifications and the expression of microRNAs. This systematic review aims at investigating the epigenetic markers affected by SLE during adolescence and their (causal) contribution to the onset of depression later in life. In line with the PRISMA 2020 guidelines and following a pre-registered protocol (CRD42023441784), PubMed, Web of Science and Embase were screened and 30 studies, including both rodents (n = 19) and humans (n = 11), met the pre-defined inclusion criteria. The preclinical findings converge on SLE-related changes in DNA methylation of Bdnf gene and alterations in microRNAs implicated in the regulation of Bdnf- and glucocorticoid-related pathways. The clinical studies focused primarily on DNA methylation and microRNAs alterations. Whilst a consensus on specific SLE-related epigenetic modifications did not emerge, novel pathways, including extracellular vesicle (EV) miRNAs, should be further investigated to be employed as biomarkers for preventive screening. Overall, our systematic review provides early suggestive evidence on the role of epigenetic mechanisms in mediating the effects of SLE in adolescence and the consequent onset of depression-relevant symptoms in later life. However, the paucity and the heterogeneity of the findings highlight the need for additional studies to address this fundamental research question and provide solid evidence for causality. Show less

Depression is a leading cause of global disability and is increasingly recognized as a multifactorial disorder characterized by fundamental disruptions in neuroplasticity, including diminished hippocampal neurogenesis, impaired synaptic plasticity, and dysregulated stress-response systems. Given the limited efficacy of conventional pharmacological treatments, lifestyle-based interventions-most notably physical exercise-have gained considerable attention for their antidepressant effects, partly mediated by secreted exerkines. Among these, adiponectin has emerged as a particularly compelling candidate linking metabolic regulation to neuroplasticity and mood. Recent evidence suggests that adiponectin contributes to the antidepressant effects of exercise by modulating hippocampal neurogenesis, neuroinflammation, and brain-derived neurotrophic factor (BDNF) signalling. Despite these advances, the mechanisms by which adiponectin influences depression remain incompletely understood. This review synthesizes current knowledge on adiponectin's role in depression pathophysiology, with emphasis on its capacity to enhance neuroplasticity and hippocampal neurogenesis, and its potential to mediate exercise-induced antidepressant effects via defined molecular pathways. Building on these insights, we discuss adiponectin's translational promise as both a predictive biomarker of treatment response and a novel therapeutic target. By integrating preclinical and clinical evidence, this review offers a comprehensive perspective on adiponectin's involvement in depression while identifying critical gaps to guide future mechanistic research. Show less

Decreased cerebrospinal fluid (CSF) levels of synaptic proteins, possibly reflecting impaired synaptic function, have been observed in major depressive disorder (MDD). To investigate the diagnostic utility of the soluble N-ethylmaleimide-sensitive-factor attachment receptor (SNARE) complex protein, synaptosomal-associated protein of 25 kDa (SNAP-25), for MDD. Overall, 208 participants with one of MDD, schizophrenia (SCZ) or bipolar disorder (BD), and healthy controls (HCs) were retrospectively enrolled. CSF levels of SNAP-25 were assessed relative to MDD characteristics and the diagnostic potential was analysed. In subgroups of patients, CSF levels of presynaptic neurexin 3 (NRXN3), postsynaptic neurogranin (NRGN) and Alzheimer's disease biomarkers were measured for comparison. SNAP-25 levels, but not the levels of the other synaptic markers, were significantly decreased in MDD compared with HCs, allowing for discrimination with 68% sensitivity and 67% specificity. SNAP-25 was not associated with MDD severity or antidepressant medication. Compared with HCs, SCZ also displayed decreased SNAP-25 enabling discrimination with 64% sensitivity and 77% specificity. There were strong correlations between levels of synaptic proteins and established Alzheimer pathology markers, with subtle differences in the association pattern between disorders. Our data suggest that SNAP-25, NRXN3 and NRGN versus beta-amyloid and phosphorylated tau protein 181 (ptau) are regulated differentially across psychiatric disorders and that SNAP-25 has a moderate diagnostic potential for MDD and SCZ. We propose that CSF SNAP-25 level might represent an integrated readout of reduced synaptic function, rather than of synaptic degeneration, in MDD. Further studies are needed to analyse whether this potential can be increased by using multimarker measurements and whether it will be possible to subtype psychiatric disorders according to synaptic involvement in pathophysiology. SNAP-25 and other synaptic proteins in CSF might aid diagnosis and subtyping of MDD and SCZ. The current development of sensitive methods to also determine synaptic proteins in blood samples from patients will advance the validation of the biomarker potential and contribute to understanding of synaptic involvement in the pathophysiology of MDD and SCZ. Show less