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). Several studies have also found it to be effective for treating suicidal ideation.
“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 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 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.
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