Each enrolled healthy control was encouraged to suggest other potential individuals for the study. This study provided evidence that, compared with healthy controls, chronic ketamine users have widespread reductions in cortical thickness. Our study underscores the importance of the long-term effects of ketamine on brain structure and serves as a reference for the antidepressant use of ketamine.
MRI data acquisition
They compared fluoxetine (an SSRI antidepressant) with ketamine to determine their therapeutic effectiveness and found that ketamine normalised the glutamate and ERK phosphorylation-related pathway (including the PSD protein abnormalities in the AMY and PFC) after 24 h (Lee et al. 2019). This, brain changes associated with long-term ketamine abuse, a systematic review pmc effectively reversed the stress-induced changes in the synaptic proteins bought on by the model, as opposed to the minimally observed stress change in the fluoxetine-treated mice (Lee et al. 2019). This systematic review synthesises the current research findings on these molecular interactions and evaluates their immediate and sustained effects on PTSD treatment outcomes. By integrating data from diverse research methodologies, including longitudinal studies, randomised controlled trials, and meta-analyses, this review endeavours to clarify the complex mechanisms by which ketamine exerts its effects and maintains its efficacy over time. By understanding these mechanisms, the aim is to provide a molecular basis for the clinical efficacy of ketamine crucial for optimising treatment protocols and improving outcomes for PTSD patients as a step towards precision medicine. S-ketamine’s rapid metabolism and potent NMDA receptor activity allow for effective low-dose treatments but come with an increased risk of dissociative side effects (Zanos and Gould 2018).
Ketamine and Neuroimaging in Depression
This modulation enhances the expression of key synaptic proteins such as AMPA receptor subunits (e.g., GLuA2), BDNF, and postsynaptic density proteins (e.g., PSD-95), all of which are crucial for maintaining synaptic plasticity and functional connectivity. Additionally, ketamine’s activation of the mTOR pathway has been shown to promote synaptogenesis and protein synthesis, reversing synaptic deficits induced by chronic stress. Molecular studies have further demonstrated that ketamine reduces the dysregulation of GABAergic and glutamatergic systems in PTSD, normalising neurotransmission in critical brain regions like the mPFC and HPC, leading to improved behavioural outcomes. The only long-term stress induced mouse model administered a daily chronic dose of 60 mg/kg ketamine over a 6-month period and found reduced mRNA levels of IL-6 and IL-1β and TNF-α in the HPC.
- Our patient also developed renal failure and some other diseases, which may have been related to his brain atrophy.
- In the same sample, the authors compared smoking chronic ketamine users with non-ketamine smokers and with non-ketamine, non-smokers by performing fMRI.
- It was also shown that ketamine is safer and more effective in regional than in general anesthesia.
- Participants were treated with a single (0.71 mg/kg) infusion or an additional higher dose (1.41 mg/kg) if they were identified as ketamine non-responders and or were observed to be struggling to maintain abstinence.
- BERT is one of the state-of-the-art approaches in natural language processing, to understand the meaning of words and sentences in a way that is similar to how humans do, by taking into account the context in which they are used.
Post-Traumatic Stress Disorder (PTSD)
By identifying these regions as therapeutic targets, researchers can better understand how ketamine alleviates PTSD symptoms, potentially leading to new effective treatments (Albuquerque et al. 2022). The metabolism of ketamine in rodents quickly produces active metabolites such as NK and HNK, which play a significant role in its antidepressant properties. These metabolites are known to boost synaptic plasticity and promote neurogenesis in critical brain areas such as the HPC and PFC, which are essential for mood and cognitive functions (Schwenk et al. 2021).
Chronic Neuropathic Pain
In a sample of 10 unmedicated OCD outpatients, Rodriguez et al37 administered a single dose of ketamine in addition to exposure-based CBT. Participants received a 90 minutes CBT session the day before a single 40-minutes IV ketamine (0.5mg/kg) infusion, followed by 10 hours of exposure sessions delivered over 2 weeks. A significant decrease in OCD symptoms as measured by the YBOCS was reported at 4 weeks post infusion among 8 of the 9 patients who completed the ketamine infusion. Dore et al23 collected data from 235 patients with a wide range of psychological and substance use related disorders (MDD, PTSD, ADHD, GAD, BPD, SUD, OCD) in three private psychiatric practices in Northern California.
Understanding and enhancing ketamine’s therapeutic potential for PTSD requires identifying the specific brain regions it affects. Known for its rapid antidepressant effects, ketamine influences several key areas involved in emotion regulation, memory, and stress response. The PFC, critical for decision-making and executive processing, often shows impaired function in PTSD patients. Ketamine’s impact on the PFC may directly improve these cognitive functions (Fremont et al. 2023). While driving under the influence of drugs, drivers are more likely to be involved in and cause more accidents than drivers who do not drive under the influence.
Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article. Although ketamine — a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist — is valued for its clinical applications in anesthesia and pain management, and esketamine (the S-enantiomer of ketamine) has begun to be used for treatment-resistant depression,1 its widespread abuse is a growing problem. Having previously established the effect of long-term, non-medical use of ketamine on grey- and white-matter structure,2,3 understanding these with greater specificity is a pressing challenge. Navigation from memory also produced greater activation in the parahippocampal gyrus bilaterally in the control group but not the ketamine group.
- The simultaneous use of ketamine and drugs that reduce liver metabolism by inhibiting CYP3A4 enzymes of the cytochrome P450 enzyme system (i.e., clarithromycin, ketoconazole) can increase the serum levels of ketamine with serious consequences.
- A greater understanding of the underlying mechanism of cortical thickness reductions among patients with ketamine use disorder could lead to the marked improvement of risk–benefit ratios of esketamine use for people with treatment-resistant depression.
- In PTSD, where BDNF levels may be reduced, this can lead to altered HCN1 activity, which may affect neuronal excitability and synaptic plasticity (Hou et al. 2018; Kim and Johnston 2018).
- As for ECT, the need for general anesthesia and a facility to perform the procedure inherently makes it less accessible than other treatments 11.
Opioid Use Disorder
Ketamine’s pharmacokinetic characteristics are not changed due to extracorporeal membrane oxygenation (ECMO) because it is less lipophile than other sedative agents and has minor protein binding 73. Recent studies focused more on using ketamine alone or in combination with local anesthetics in regional anesthesia 68. It was also shown that ketamine is safer and more effective in regional than in general anesthesia. Its application as an anesthetic agent at the surgical site ensures effective analgesia without notable side effects in children undergoing cleft palate surgery.
Structural Differences: Gray Matter
Following multiple sublingual doses of ketamine administered in combination with Mindfulness-Based Cognitive Therapy (MBCT) and Functional Analytic Psychotherapy (FAP) over a 13 days scores on the Posttraumatic Cognitions Inventory decreased at 2-weeks, which was maintained up to a 6-month follow-up. In addition to self-reported reductions in anxiety following treatment, severe depression scores on the BDI-II decreased from baseline to the 2-week time point, but returned to severe levels at the 6-month follow-up. The simultaneous use of ketamine and drugs that reduce liver metabolism by inhibiting CYP3A4 enzymes of the cytochrome P450 enzyme system (i.e., clarithromycin, ketoconazole) can increase the serum levels of ketamine with serious consequences. The administration of ketamine with other CNS depressants such as tramadol, alcohol, and opioids increases the risk of respiratory depression, profound sedation, and coma.
A niche but notable discussion (1% of tweets) compared ketamine to electroconvulsive therapy (Topic 8), indicating a preference for the former for (likely treatment-resistant) depression due to fewer side effects and potential effectiveness. Within this theme, a debate on the use of esketamine for treating depression stood out, making up 4.2% of the discussions (Topic 3). Many users expressed concerns and critiques, questioning the efficacy of esketamine compared to other standard treatments. The FDA’s approval of a ketamine-based nasal spray for depression treatment sparked reactions that formed 2.2% of the tweet pool, with the public oscillating between hope and apprehension (Topic 4).