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Efficacy of ketamine for major depressive episodes 6 weeks later

Most studies on ketamine investigate the effects up to one week later. After that period of time, it’s unclear if the antidepressant effects hold up.

Until now….

A new meta-analysis adds evidence that ketamine can reduce depressive episodes up to six weeks later. The study finds large reductions in the severity of depressive episodes.

This study brought together data from 41 studies, of which 5 reported the data at the six-week mark. The results add more evidence that ketamine may be useful for the acute treatment of depressive symptoms. This can be done to alleviate immediate suffering, and provide a bridge to more long-term care.

How this study fits in

Ketamine may not be front and center in the race for the best psychedelics, it is the one that is currently available for use and is providing benefits to patients. Studies like the current one can help us understand if and how long-term positive effects can be achieved.

Acute adverse reactions and generally positive outcomes

Using psychedelics is generally believed to be safe for most people. An elevated heart rate or a rise in blood pressure is what clinical studies with LSD find for instance. Adverse events reported are usually focused on psychological effects. Transient anxiety, fear of ego dissolution, and negative feelings are among the effects reported.

The current case series investigated the negative experience of seven (out of 40) participants in an ayahuasca ceremony. Although, and possibly because, they had acute distressful experiences, on average the participants improved on scores of mental health.

This is what they experienced:

  • Two participants no longer had psychiatric symptoms after the ceremony.
  • Two others had significantly reduced symptoms, whilst one received a new diagnosis afterward.
  • The setting contributed to the acute negative effects, where in one case the guide felt asleep whilst people were still high.

Earlier reports from the União do Vegetal indicated only a handful of negative experiences over 25,000 sessions. Whilst the current study found that 17.5% of participant reported acute adverse events. Although the participants did experience positive outcomes, this study may lead us to believe that more (transient) negative experiences are happening than previously thought.

Research Readout

Microdosing and yoga as complementary practices. Participants who practiced both had the highest absorption score, exhibited higher levels of wellbeing, and had less depression and anxiety, compared to people who either practiced yoga or microdosing, and participants recruited as controls.

The psychedelic experience on ketamine correlates with ketamine’s antidepressant effects. Three dimensions of the altered states of consciousness scale correlated with lower scores on depression scores.