Ketamine's immediate effects on PTSD involve changes in GABA, glutamate, and glutamine levels that trigger re-regulation of BDNF, enhancing synaptic plasticity via pathways such as TrkB and PSD-95, along with other molecular influences. Sustained therapeutic effects arise from neurotransmitter remodulations and prolonged changes in gene expression, including mTOR-mediated BDNF expression and epigenetic modifications. These molecular changes promote long-term synaptic stability and re-regulation in key brain regions. Understanding these sustained mechanisms is critical for developing safe and effective personalised treatments.
A six-week course of oral ketamine produced substantial and persistent changes in gene expression in 23 people with PTSD. Short-term effects included suppression of inflammation and antimicrobial activity; long-term effects shifted toward sustained immune regulation, inflammation remodulation, and tissue repair. Over four weeks, the number of genes whose activity changed rose by 37%, the magnitude of expression changes increased 6.5-fold, and pathway activity strengthened 8.8-fold. Key immune and inflammatory pathways modulated included interferon alpha/beta signaling, IL-17 signaling, cytokine storm signaling, neutrophil degranulation, and antimicrobial peptide signaling. Central regulators such as IL-6, IL-1β, IFI27, IL-10, CXCL8, SOCS1/3, and CAMP were implicated. These molecular changes point to mechanisms underlying ketamine's long-term therapeutic effects and suggest avenues for personalized maintenance therapy to prevent relapse.
In a 6-week open-label trial of low-dose oral ketamine for PTSD, blood samples from 25 participants showed a small but significant decrease in both BDNF and VEGF-A levels after treatment, with a positive correlation between the two biomarkers. This suggests ketamine's effects may involve a reciprocal interaction between BDNF and VEGF-A, offering potential insight into a biological mechanism for PTSD symptom reduction. Novel relationships between FKBP51, serotonin, and clinical scales were also observed. No significant changes in immune cytokines were detected, possibly because half the participants had low-grade inflammation and half did not.