Full study

There is a growing interest in the psychiatric properties of the dissociative anesthetic ketamine, as single doses have been shown to have fast‐acting mood‐enhancing and anxiolytic (anti-anxiety) effects, which persist for up to a week after the main psychoactive symptoms have diminished.

Therefore, ketamine poses potential beneficial effects in patients with refractory (treatment-resistant) anxiety disorders, where other conventional anxiolytics have been ineffective. Ketamine is a noncompetitive antagonist of the N‐methyl‐d‐aspartate (NMDA) glutamate receptor, which underlies its induction of pain relief and anesthesia.

However, the role of NMDA receptors in anxiety reduction is still relatively unknown. To fill this paucity in the literature, this systematic review assesses the evidence that ketamine significantly reduces refractory anxiety and discusses to what extent this may be mediated by NMDA receptor antagonism and other receptors.

We highlight the temporary nature of the anxiolytic effects and discuss the high discrepancy among the study designs regarding many fundamental factors such as administration routes, complementary treatments and other treatments.

Background

Ketamine is reported to have rapid antidepressant effects, however there is limited understanding of the time-course of ketamine effects beyond a single infusion. A previous report including 10 participants with treatment-resistant major depression (TRD) found that six ketamine infusions resulted in a sustained antidepressant effect. In the current report, we examined the pattern and durability of antidepressant effects of repeated ketamine infusions in larger sample, inclusive of the original.

Methods

Participants with TRD (n=24) underwent a washout of antidepressant medication followed by a series of up to six intravenous (IV) infusions of ketamine (0.5 mg/kg) administered open-label three times weekly over a 12-day period. Participants meeting response criteria were monitored for relapse for up to 83 days from the last infusion.

Results

The overall response rate at study end was 70.8%. There was a large mean decrease in Montgomery–Asberg Depression Rating Scale (MADRS) score at two hours following the first ketamine infusion (18.9±6.6, p<0.001) and this decrease was largely sustained for the duration of the infusion period. Response at study end was strongly predicted by response at four hours (94% sensitive, 71% specific). Among responders, median time to relapse following the last ketamine infusion was 18 days.

Conclusions

Ketamine was associated with a rapid antidepressant effect in TRD that was predictive of a sustained effect. Future controlled studies will be required to identify strategies to maintain an antidepressant response among patients who benefit from a course of ketamine.

TL;DR: Psycholytic refers to "microdosing," aka taking very small doses regularly, and "psychedelic" refers to "macrodosing," aka taking large doses for a few targeted sessions.

Your contribution is what makes it thrive, so please share your journeys and thoughts!

This is a place to discuss therapeutic use of various psychedelic substances, from ketamine to psilocybin to MDMA and others.

We welcome anything from personal accounts to scientific articles and talks.

The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:

Rules

• Posts containing medical advice or diagnosing others are not allowed. Please keep the post focused on your personal experience.

• Please do not recommend specific dosages or treatment methods to others. It’s OK to talk about your personal experience.

• Harassment of any kind is not tolerated. Do not harass any user for any reason including treatment choices, race, religion, gender, sexuality, disability, etc.

• We do not allow promotion, solicitation, or affiliate links. For interviews, surveys, and studies, please contact the moderators.

Related Communities

• Mental Health

• Therapy

Community Moderation

For inquiry on becoming a moderator of this community, please send a message to the current moderators.