Stress hormone marker was lower in people with both depression and PTSD, before and after ketamine

The question

Do people in a major depressive episode who also have post-traumatic stress disorder (PTSD) show different levels of a stress-related hormone system than those with depression alone, and does a single ketamine infusion change that?

What they did

Researchers measured copeptin in blood, a stable marker that stands in for the hormone arginine vasopressin (AVP), which helps regulate the body’s stress response. They compared people having a major depressive episode with PTSD, people having a depressive episode without PTSD, and healthy volunteers. They also looked at other stress-hormone measures (CRH, ACTH and urine cortisol) and at symptom ratings and behavioural traits. In a subgroup of patients, they measured how these markers changed after a single low (subanesthetic) dose of ketamine given by infusion.

What they found

People with both depression and PTSD had lower baseline copeptin levels than those with depression alone, and their copeptin dropped less after the ketamine infusion. Copeptin was not linked to the primary mood diagnosis, nor to the severity of depression, anxiety, post-traumatic stress, loss of pleasure, suicidal thinking, or childhood trauma history. The one exception was aggression: higher baseline copeptin was associated with verbal aggression, and this link was weaker in those who also had PTSD. The abstract reports no specific numbers for group sizes or hormone levels.

The fine print

The abstract does not state how many people took part, how many received ketamine, or the size of any difference, which makes the findings hard to judge. This was an exploratory study of a blood marker, not a test of whether ketamine helped symptoms, and copeptin is only a stand-in for the hormone of interest. There was no reported placebo comparison for the hormone changes, and follow-up appears limited to the period around a single infusion. This summary is based on the abstract only.

What it means

The results hint that people with both depression and PTSD may have a distinct stress-hormone profile that does not track with how severe their symptoms are, but this is early exploratory work and says nothing yet about whether ketamine works better or worse for them.

Evidence grade: Low. Exploratory biomarker analysis within a trial, with no sample size reported, no placebo comparison for the biomarker findings, and a surrogate blood marker rather than a clinical outcome.

This summary is based on the study’s published abstract.