Ketamine was originally approved by the US Food and Drug Administration (FDA) as an anesthetic, but is increasingly being used to treat mood disorders, such as treatment-resistant depression, anxiety disorders, and post-traumatic stress disorder (PTSD).1,2 Several studies have also found it to be effective for treating suicidal ideation.3,4
“Ketamine can play an important role in the treatment of anxiety disorders,” according to Prakash Masand, MD, co-founder, chairman, and CEO of Centers of Psychiatric Excellence (COPE) (https://www.copepsychiatry.com) and adjunct professor at the Academic Medicine Education Institute, Duke-National University of Singapore Medical School (Duke-NUS).
“Nowadays, people with anxiety disorders are treated either with a generic antidepressant, such as an SSRI (selective serotonin reuptake inhibitor), an SNRI (selective norepinephrine reuptake inhibitor), or a benzodiazepine and if they don’t respond to one of these, they get a trial of another or several more,” Dr Masand said.
However, between 30% and 40% of these patients will not achieve remission, despite 3 or 4 different traditional agents, and even with evidence-based nonpharmacologic therapies, such as cognitive behavioral therapy (CBT) or mentalization-based therapy (MBT), he noted.
“No good current strategies are available for these non-responders, so novel agents are being studied — including ketamine, which is accumulating an evidence base as [being] rapidly effective for an array of anxiety disorders, including social anxiety disorder (SAD) and PTSD,” he said.
How Does Ketamine Work?
A growing body of evidence points to the role of glutamate, a widely distributed excitatory neurotransmitter, in mediating response to stress and the formation of traumatic memories.2 Ketamine is an ionotropic glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist. Its antidepressant and anti-anxiety effects are presumed to occur through activating synaptic plasticity by increasing brain-derived neutrophic factor translation and secretion and also by inhibiting glycogen synthase kinase-3 and activating mammalian target of rapamycin signaling.5
Brain-derived neutrophic factor plays a role in behavioral responses to classical antidepressants, but the impact on synaptic plasticity may take several weeks to manifest. In contrast, ketamine-mediated synaptic plasticity changes appear to occur within a matter of hours after ketamine administration.5
“The current thinking is that eventually, 6 to 12 weeks after initiating treatment with traditional antidepressants, dendritic growth and increased synaptic connections occur but with ketamine, these can occur within 24 hours of the infusion,” Dr Masand said.
Ketamine and Anxiety: An Increasing Evidence Base
“Ketamine has been studied and shown [to be] effective with an array of anxiety disorders, including SAD, general anxiety disorder (GAD), and PTSD, although the data on its effectiveness in obsessive compulsive disorder (OCD) are more mixed,” Dr Masand observed.
- A small study of patients with GAD and/or SAD (n=12) compared 3 ascending ketamine doses to midazolam. Each was given at 1-week intervals, with midazolam counterbalanced in dosing position across patients. Ketamine was found to dose-dependently improve scores on the Fear Questionnaire. Moreover, it’s impact on decreasing theta frequency in the right frontal sites assessed via electroencelphalogram (EEG) was comparable to that of conventional anxiolytics.6
- Glue et al evaluated the efficacy and safety of ketamine in 12 patients with refractory GAD and/or SAD who were not currently depressed using an ascending single-dose at weekly intervals study design. Within 1 hour of dosing, patients reported reduced anxiety, which persisted for up to 7 days.7
- A continuation of that study evaluated the impact of maintenance treatment ketamine in patients with GAD and/or SAD (n=20) and found that 18 of the 20 patients reported ongoing improvements in social functioning and/or work functioning during maintenance treatment. The researchers concluded that maintenance therapy ”may be a therapeutic alternative for patients with treatment-refractory GAD/SAD.”8
“What is interesting about this study is that the impact of just one infusion lasted for 14 weeks, suggesting that patient[s] with anxiety disorders might have longer maintenance of response than patients with major depression, where the response has been maintained for only one week,” Dr Masand commented.
- A study of patients with anxious and non-anxious bipolar depression (n=21 for both groups) found that both anxious and non-anxious patients with bipolar depression had significant antidepressant responses to ketamine, although the anxious depressed group did not show a clear antidepressant response disadvantage over the non-anxious group.9 “Given that anxiety has been shown to be a predictor of poor treatment response in bipolar depression when traditional treatments are used, our findings suggest the need for further investigations into ketamine’s novel role in the treatment of anxious bipolar depression.,” the investigators concluded.9
- Noninvasive Brain Stimulation of Prefrontal Cortex in Trait Anxiety
- Predictors of CBT Outcomes Identified in Youths With Anxiety Disorders
- Psychotic Experiences Linked to Anxiety and Somatic Symptoms in Preadolescent
- An open-label trial of ketamine in 10 patients with treatment-refractory OCD found that ketamine’s effects on OCD symptoms, in contrast to depressive symptoms, did not seem to persist or progress after the acute effects of ketamine had dissipated.10
- On the other hand, another randomized controlled trial (RCT) of 15 patients with OCD found that anti-OCD effects from a single intravenous dose of ketamine persisted for more than 1 week in some patients with OCD with constant intrusive thoughts, demonstrating that “a drug affecting glutamate neurotransmission can reduce OCD symptoms without the presence of an [SSRI].”11
In PTSD, there is “mounting evidence for a role of the excitatory neurotransmitter glutamate in stress responsiveness, the formation of traumatic memories, and the pathophysiology of PTSD, raising the possibility of identifying novel glutamatergic interventions for this disorder.”12
- One double-blind study demonstrated that infusion of ketamine rapidly and significantly reduces symptom severity in patients with PTSD compared with midazolam.2
- Another study found that administration of ketamine immediately after witnessing a traumatic event has been shown to prevent the enhancement of passive avoidance learning in mice.13Ketamine may thus target the mechanisms involved in the consolidation of traumatic memory and may enable the brain to reconsolidate memory and release trauma.14
- A case study of a child with PTSD reported remission from behavioral dysregulation after receiving procedural ketamine.15
Drawbacks and Potential Adverse Effects
The main concern regarding the use of ketamine for anxiety disorders is the lack of a road map regarding maintenance, Dr Masand noted.
“At COPE, we have found that roughly 30% to 40% of our patients being treated with ketamine require maintenance infusions, and we highly personalize this approach so that patients can identify early signs of recurrence or relapse and we can devise a treatment schedule to prevent them,” he said.
Some patients continue treatment with pharmacotherapy, including standard antidepressants, benzodiazepines, or a mood stabilizer such as valproate and some patients become more receptive to psychotherapies such as CBT,” he stated.
However, “there is very little data regarding what happens long-term in this patient population.”
“Most side effects are mild and transient,” Dr Masand reported. “Patients must be monitored because of potential increases in blood pressure and pulse.”
Additional adverse events include nausea or vomiting, which are also mild and transient. Patients may be pre-treated with prophylactic anti-nausea medication, such as ondansetron, to pre-empt these symptoms, he said.
Some patients experience dissociation, or an out-of-body experience, which is also usually transient but seen by some patients as “annoying,” he noted. “Dissociative experiences are sometimes seen as a biomarker for insufficient response and suggest that the dose should be increased.”
Providers should be aware that cystitis and lower urinary tract pathologies (eg, detrusor over-activity) have been reported in long-term ketamine users, but typically only at high doses.16
Ketamine’s psychedelic effects make it a” popular recreational drug.”16 At lower doses, the predominant effects are stimulating, and users experience mild dissociation with hallucinations and a distortion of time and space. However, higher doses can induce more severe, schizophrenia-like symptoms and perceptions.16 Although these effects resolve rapidly, long-term use “can cause more pronounced and persistent neuropsychiatric symptoms. For this reason, ketamine should be “used cautiously with other drugs that alter mood and perception, including alcohol, opioids, benzodiazepines and cannabis.”16
“Ketamine for treatment-resistant depression has a robust evidence base and a rapidly-growing evidence base for its use in anxiety disorders,” Dr Masand said.
“Given the gaps in current treatment, this promising agent is occupying a more promising role in treatment of anxiety disorders, such as PTSD. Considering how common PTSD is, ketamine can make an important difference for a large number of people who suffer from this debilitating condition,” he concluded.
First Person Account of Ketamine Therapy: An Interview with Kimberly Palmer
To gain insight into the experience of ketamine treatment in a person with depression and anxiety, Psychiatry Advisor interviewed Kimberly Palmer of Los Angeles, California. Ms Palmer received treatment at the Ketamine Clinics of Los Angeles (https://www.ketamineclinics.com). Ms Palmer works as a program manager for a consulting company where she organizes and runs corporate events for small groups.
Psychiatry Advisor: What made you decide to pursue ketamine treatment?
Ms Palmer: I was raised in an abusive home, and as an adult I had severe major depression, as well as anxiety. I was treated with medications, such as antidepressants, but they had many adverse events and they ended up making me feel like a zombie, so I discontinued them. I managed okay for a while, but then I had another major depressive episode.
I was receiving psychotherapy at the time and it was only moderately helpful — not enough to stop the episode. Fortunately, I knew someone who works at a ketamine clinic. She told me how many patients had been helped by ketamine and I was interested, mostly because the adverse events of ketamine seemed mild and are not long-term.
Psychiatry Advisor: What were your experiences during your infusion?
Ms Palmer: I felt incredible during the infusion. The best way I can describe it is by referring to the movie Avatar, specifically the scene in which the protagonist is walking through a jungle at night for the first time and touching all the plants, which light up with pretty colors—very vivid, colorful, and not linear. There was the sensation of being on a sort of roller coaster, riding through different scenes.
At one point, it felt as though my chair was on a cloud. Then suddenly, the chair disappeared and I was floating on the cloud. It was a wonderful experience.
Psychiatry Advisor: How did the ketamine treatment affect you afterwards?
Ms Palmer: After only one treatment, it was as if a switch had flipped in my brain that allowed me to digest things and move beyond my trauma. Before the infusion, a lot of what was going on with me had to do with self-esteem issues and negative self-talk. These were behaviors learned over many years. After the infusion, the negative self-talk immediately disappeared. All of those thoughts — such as telling myself I am not good enough — that were preventing me from working through emotional issues, were resolved. I was able to start looking at things more objectively rather than taking them personally, and not take on responsibility for other people’s emotions and reactions.
I am currently working with a therapist and a life coach to help me feel more comfortable with communication because I was raised not to ask for things and to put up with anything I’m asked to do. As a result, I have developed a much more positive outlook of myself and the world.
Psychiatry Advisor: How many ketamine treatments have you had?
Ms Palmer: Over a 6-month period I had 6 treatments, which were all very helpful. Then, 6 months after the conclusion of this first series of treatments, some new issues came up, so I received 2 more — one regular 60-minute treatment and one extended 90-minute treatment.
Recently, with the holidays coming up, I decided to pre-empt the effect of some stressors and have another treatment. My most recent infusion took place the day after my father passed away. I noticed that during the infusion, I was able to steer myself away from negative thoughts about that issue. Although I cannot control what visions or experiences I might have, I do have some control over the direction of my thoughts and the after-effects have been positive and helpful.
Psychiatry Advisor: Did you have any adverse events from the treatments?
Ms Palmer: I had no negative physical effects. I had one mild bad reaction, when I came to the treatment session in an agitated state because I had gotten into a fight with someone right before. I was sad and crying by the time I finished the infusion. But I was in a bad headspace before I even walked into the room. And my experience was not scary, only sad.
Psychiatry Advisor: What impact has your treatment had on your day-to-day life?
Ms Palmer: My depression had interrupted my schooling. I was in school for 3 and a half years and then I hit a roadblock. After the treatments, I was able to complete my studies and graduated with a BA in business administration and management.
My job is stressful. I counterbalance the stress with hobbies like surfing and photography. But there are still stressors, and I have a dog who is reaching the end of life, which is affecting me. The ketamine treatments have helped me to manage those stressors.
- Sanacora G, Frye MA, McDonald W, et al. A consensus statement on the use of ketamine in the treatment of mood disorders. JAMA Psychiatry. 2017;74(4):399-405.
- Feder A, Parides M, Murrough JW, et al. Efficacy of intravenous ketamine for treatment of chronic posttraumatic stress disorder: a randomized clinical trial. JAMA Psychiatry. 2014;71(6):681-688.
- Murrough JW, Soleimani L, DeWilde KE, et al. Ketamine for rapid reduction of suicidal ideation: a randomized controlled trial. Psychol Med. 2015;45(16):3571-3580.
- Wilkinson ST, Ballard ED, Bloch MH, et al. The effect of a single dose of intravenous ketamine on suicidal ideation: a systematic review and individual participant data meta-analysis. Am J Psychiatry. 2018;175(2):150-158.
- Schwartz J, Murrough JW, Iosifescu DV. Ketamine for treatment-resistant depression: recent developments and clinical applications. Evid Based Ment Health. 2016;19(2):35-38.
- Shadli SM, Kawe T, Martin D, McNaughton N, Neehoff S, Glue P. Ketamine effects on EEG during therapy of treatment-resistant generalized anxiety and social anxiety [published online April 24,2018]. Int J Neuropsychopharmacology. doi:10.1093/ijnp/pyy032
- Glue P, Medlicott NJ, Harland S, et al. Ketamine’s dose-related effects on anxiety symptoms in patients with treatment refractory anxiety disorders. J Psychopharmacol. 2017;31(10):1302-1305.
- Glue P, Neehoff SM, Medlicott NJ, Gray A, Kibby G, McNaughton N. Safety and efficacy of maintenance ketamine treatment in patients with treatment-refractory generalised anxiety and social anxiety disorders. J Psychopharmacol. 2018;32(6):663-667.
- Ionescu DF, Luckenbaugh DA, Niciu MJ, Richards EM, Zarate CA. A single infusion of ketamine improves depression scores in patients with anxious bipolar depression. Bipolar Disord. 2014;17(4):438-443.
- Bloch MH, Wasylink S, Landeros-Weisenberger A, et al. Effects of ketamine in treatment-refractory obsessive-compulsive disorder. Biol Psychiatry. 2012;72(11):964-970.
- Rodriguez CI, Kegeles LS, Levinson A, et al. Randomized controlled crossover trial of ketamine in obsessive-compulsive disorder: proof-of-concept. Neuropsychopharmacology. 2013;38(12):2475-2483.
- Girgenti MJ, Ghosal S, LoPresto D, Taylor JR, Duman RS. Ketamine accelerates fear extinction via mTORC1 signaling. Neurobiol Dis. 2016;100:1-8.
- Ito W, Erisir A, Morozov A. Observation of distressed conspecific as a model of emotional trauma generates silent synapses in the prefrontal-amygdala pathway and enhances fear learning, but ketamine abolishes those effects. Neuropsychopharmacology. 2015; 40(11):2536-2545.
- Fattore L, Piva A, Zanda MT, Fumagalli G, Chiamulera C. Psychedelics and reconsolidation of traumatic and appetitive maladaptive memories: focus on cannabinoids and ketamine. Psychopharmacology (Berl). 2018;235(2):433-445.
- Donoghue AC, Roback MG, Cullen KR. Remission from behavioral dysregulation in a child with PTSD after receiving procedural ketamine. Pediatrics. 2015;136(3):e694-e696.
- Li L, Vlisides PE. Ketamine: 50 years of modulating the mind. Front Hum Neurosci. 2016;10:612.