São PauloPTSD leaves a measurable blood signature in women.
Longitudinal RNA-sequencing of women in Brazil after sexual assault found persistent immune and metabolic dysregulation in blood over 12 months.
Researchers say a blood marker could support diagnostic and disability claims for PTSD, which has no approved clinical blood test.
Sources: Nature
THE DIAGNOSTIC GAP
PTSD is diagnosed entirely by clinical interview against DSM-5 criteria — there is no blood test, no scan, no biomarker accepted by any regulator. A patient's diagnosis depends on whether they can articulate their symptoms to a clinician who believes them.
WHAT TRANSCRIPTOMICS MEASURES
DNA is the blueprint; the transcriptome is which pages are actively being read at a given moment. RNA-sequencing counts the messenger RNA molecules in a sample, revealing which genes are switched on and how loudly. The same genome can produce wildly different transcriptomes depending on stress, infection, or trauma.
THE INFLAMMATION HYPOTHESIS
PTSD has been linked for two decades to chronic low-grade inflammation — elevated C-reactive protein, interleukin-6, and TNF-alpha in patients years after the trauma. The new finding is not that immunity is involved, but that the dysregulation is durable enough to read as a stable signature 12 months out.
WHY WOMEN, WHY SEXUAL ASSAULT
Women develop PTSD at roughly twice the rate of men after comparable trauma, and sexual assault carries the highest conditional risk of any trauma type — around half of survivors meet criteria. Studying this cohort maximizes statistical power: a real biological signal is most likely to show up where the disorder is most concentrated.
THE BIOMARKER BAR
For a blood test to enter clinical use it must be sensitive (catches real cases), specific (does not flag depression or general inflammation), stable across labs, and validated in independent cohorts. Many PTSD biomarker candidates have cleared the first two and failed the last two. Replication is where the field has historically broken down.
THE METABOLIC LAYER
Beyond immunity, the study flags persistent metabolic dysregulation — the cellular machinery for converting glucose and lipids into energy runs differently in trauma-exposed women a year later. This mirrors findings in chronic stress research where the HPA axis (the brain's cortisol system) reshapes mitochondrial function long after the stressor ends.