Over six ketamine infusions, combat veterans' PTSD and depression symptoms fell.
A 2019 study gave a series of ketamine infusions to U.S. combat veterans living with combat-related PTSD.
Thirty U.S. combat veterans with combat-related PTSD received a series of six high-dose ketamine infusions, designed to produce an intense dissociative experience. Measured by questionnaire before the first and after the sixth infusion, average PTSD scores fell by roughly half (from about 56 to 31) and depression scores similarly (from about 19 to 10). Self-reported substance use didn't significantly change. Because this was an observational study with no comparison group and relied on self-report, it can't separate the drug's effect from expectation — but it adds to the signal that ketamine may help combat-related PTSD, which the authors say needs controlled study.
This observational, single-arm study followed 30 U.S. combat veterans with combat-related PTSD through six one-hour high-dose ketamine infusions aimed at a transpersonal dissociative experience. On self-report measures before the first and after the sixth infusion, PTSD (PCL-5) fell from a mean of 56.2 to 31.3 (p<.001) and depression (PHQ) from 18.9 to 9.5 (p<.001). Self-reported substance use did not significantly decrease.
The within-person reductions are large, but the design is weak: no control or placebo group, no blinding, and outcomes by self-report, so placebo response and expectancy cannot be excluded — a serious limitation for a drug with pronounced acute subjective effects. The sample is small (n=30). The authors position it as a signal warranting further, better-controlled study.
This positive observational signal contrasts with the largest randomized, placebo-controlled trial of ketamine infusions for PTSD in military populations, which found no PTSD benefit over placebo (Abdallah et al., 2022) — a reminder that uncontrolled studies can overstate effects controlled trials do not confirm. A separate pilot pairing ketamine with prolonged exposure therapy reported preliminary feasibility (Shiroma et al., 2020).
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