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Psychedelics have emerged as a promising novel therapeutic approach for major depressive disorder (MDD). Altered activity and structural atrophy of the prefrontal cortex, hippocampus, and limbic structures are associated with depressive disorders. Psilocybin may reverse the loss of synaptic connections and restore the function of these brain regions. In this study, we investigated the effects of psilocybin on rat behavior, hippocampal neurogenesis, expression level of brain-derived neurotrophic factor (BDNF) and hypothalamic-pituitary-adrenal (HPA) axis activity. Psilocybin administered in two doses (0.6 mg/kg, s.c., 7 days apart) reversed anhedonia in stressed rats, produced antidepressant-like effects in the forced swim test (FST), and exerted anxiolytic activity in the light/dark box (LDB), elevated plus maze (EPM), and open field (OF) tests in stressed animals. Psilocybin induced hippocampal neurogenesis as evidenced by increasing the number of BrdU-positive cells (an exogenous marker of cell proliferation and survival), DCX-positive cells (a marker of immature neurons), and Ki-67-positive cells (an endogenous marker of cell proliferation) in stressed animals. Stress-induced reductions in BDNF expression levels appeared to be associated with normalization of HPA axis activity. These findings underscore the role of psilocybin-induced neuroplasticity in the antidepressant and anxiolytic mechanisms of psychedelics. Show less

There is a significant association between depressive episodes of bipolar disorder and non-suicidal self-injury (NSSI). Mindfulness-based cognitive therapy (MBCT) represents an evolution of cognitive behavioural therapy and serves as a comprehensive psychological intervention. Preliminary research suggests that MBCT may enhance cognitive flexibility and attentional adjustment in patients with depressive episodes of bipolar disorder by modulating brain activity. The aim of this study was to explore the effects of MBCT on behaviour, cognitive function, and serum precursor of brain-derived neurotrophic factor (proBDNF) levels in adolescents with depressive episodes of bipolar disorder. A total of 149 adolescent patients with bipolar disorder and depression with NSSI were randomly assigned. The Chinese version of the Adolescent Non-suicidal Self-Injury Assessment Questionnaire (ANSAQ) was used to measure NSSI symptoms. One group received MBCT in addition to treatment as usual (TAU) (n = 75), while the other group received TAU alone (n = 74). At baseline and at weeks 4 and 8 after treatment initiation, participants were assessed using the Barratt Impulsiveness Scale (BIS), the Hamilton Anxiety Scale (HAMA), the Repeatable Battery for the Assessment of Neuropsychological Status, and the Hamilton Depression Scale (HAMD). In addition, serum precursor Brain-Derived Neurotrophic Factor (proBDNF) levels were determined using an enzyme-linked immunosorbent assay. After 4 and 8 weeks of treatment, the MBCT group showed significantly greater improvement than the control group across the three BIS dimensions (motor impulsiveness, cognitive impulsiveness, and non-planning impulsiveness) (P < 0.001). HAMD scores in the MBCT group were significantly lower than those in the TAU group (4 weeks: MBCT:16.89 ± 1.45 vs TAU:17.27 ± 1.47, P < 0.05; 8 weeks: MBCT:9.24 ± 1.43 vs TAU:11.01 ± 1.84, P < 0.001). Similarly, HAMA scores were lower in the MBCT group (4 weeks: MBCT:13.14 ± 1.30 vs TAU:14.13 ± 1.65, P < 0.05; 8 weeks: MBCT:7.16 ± 1.68 vs TAU:8.17 ± 1.40, P < 0.001). Regarding cognitive function, the MBCT group demonstrated significantly higher scores in immediate memory (4 weeks: MBCT:72.31 ± 11.08 vs TAU:68.31 ± 9.36 P < 0.05; 8 weeks:MBCT:74.80 ± 13.06 vs TAU:71.87 ± 13.64, P < 0.05), delayed memory (4 weeks: MBCT:74.46 ± 11.50 vs TAU:70.20 ± 11.76, P < 0.05; 8 weeks: MBCT:76.54 ± 13.07 vs TAU:71.90 ± 12.60, P < 0.001), attention (4 weeks: MBCT:77.53 ± 11.41 vs TAU: 73.01 ± 13.21, P<0.05; 8 weeks: MBCT:84.56 ± 12.77 vs TAU:76.87 ± 11.38, P < 0.001), language ability (4weeks: MBCT:76.47 ± 12.17 vs TAU:72.13 ± 13.25 P < 0.05;8 weeks: MBCT:79.89 ± 15.02 vs TAU:74.83 ± 12.97, P < 0.05) and visuospatial ability (4 weeks:MBCT:89.04 ± 10.92 vs TAU:84.01 ± 12.67 P < 0.05;8 weeks:MBCT:90.23 ± 13.62 vs TAU:87.67 ± 12.74 P < 0.05) . In addition, serum proBDNF levels in the MBCT group were significantly lower than those in the TAU group at both 4 weeks (MBCT:1.34 ± 0.09 ng/mL vs TAU:1.40 ± 0.06 ng/mL, P < 0.05) and 8 weeks (MBCT:1.27 ± 0.07 ng/mL vs TAU:1.31 ± 0.04 ng/mL, P < 0.05). MBCT can effectively reduce impulsive behaviour, alleviate depressive and anxiety symptoms related to self-injurious behaviour in adolescents with bipolar depression, and decrease serum proBDNF levels. Additionally, immediate memory, delayed memory, attention, language, and visuospatial ability were significantly improved following treatment. Show less

Major depressive disorder (MDD) is a leading global health concern. Personalized medicine could enable a better response to antidepressants. Findings suggested optimal response genotypes of Val66Met genetic polymorphism of brain-derived neurotrophic factor (BDNF) (rs6265) in Caucasian depressed patients: selective serotonin reuptake inhibitors (SSRIs) associated with better clinical improvement in Val/Val homozygotes and selective norepinephrine reuptake inhibitors (SNRIs) or tricyclic antidepressants (TCAs) with better clinical improvement in Met-allele carriers. We aim to replicate these findings with a meta-analysis. A systematic search of PubMed was performed. All included studies assessed the efficacy of one antidepressant class (SSRIs, SNRIs, or TCAs) in Caucasian patients with a major depressive episode (MDE) in the context of MDD according to BDNF Val66Met genotypes. The primary outcome was remission (MADRS ≤ 12 or HAMD ≤ 7); secondary outcomes were changes from baseline HAMD or MADRS scores and response (≥ 50% reduction). Seven studies were included. In total, 599 patients (357 Val/Val homozygotes and 242 Met-allele carriers) were analyzed. No significant association between optimal response genotypes and remission (190 (56.4%) in the optimal and 146 (54.3%) in the non-optimal genotype response group; fixed effects model: RR = 1.02, 95% CI [0.89; 1.18], p = 0.78) was observed. Similar results were observed for score changes and response. Sensitivity analyses confirmed these findings. Statistical power for primary outcome was 95%. We showed no significant association between the expected optimal response genotype of the BDNF Val66Met polymorphism and clinical improvement after antidepressant treatment in Caucasian depressed patients. Show less

Major depressive disorder is associated with deficits in hippocampal synaptic plasticity that depend on brain-derived neurotrophic factor (BDNF) release from both axonal and dendritic compartments. Antidepressant efficacy requires enhanced BDNF signaling, thought to be mediated by drug-induced BDNF release from postsynaptic dendritic spines. Here, we show that fast-acting antidepressants rapidly trigger BDNF secretion from presynaptic terminals in hippocampal area CA3. At antidepressant-relevant concentrations, ketamine and its metabolite (2R,6R)-hydroxynorketamine (HNK) induced BDNF release within minutes from mossy fiber terminals of dentate granule neurons in rat hippocampal cultures, with no detectable secretion from dendritic spines. This antidepressant-evoked BDNF release required presynaptic NMDA receptors (preNMDARs). Conditional genetic deletion of preNMDARs from granule neurons abolished ketamine- and HNK-induced BDNF exocytosis in acute mouse hippocampal slices, establishing a presynaptic receptor mechanism for antidepressant-induced neurotrophin release. In CA3 pyramidal neurons that receive mossy fiber input, both compounds induced rapid remodeling of dendritic spines, resulting in increased spine density. Together, these findings identify presynaptic terminals as a previously unrecognized source of antidepressant-evoked BDNF release and establish a new cellular mechanism for the rapid synaptic effects of fast-acting antidepressants. Show less