Some traumas are impersonal — an accident, a natural disaster. Others carry a second layer of injury: they are inflicted by someone we trusted or depended on. A parent, a partner, a close friend. Psychologists call this betrayal trauma, and research has long suggested that it leaves a distinct mark, because it damages not only our sense of safety but our ability to trust other minds at all.

A study published in July 2026 in PLOS ONE — conducted with 209 Polish adults and co-authored by leading mentalization researchers Peter Fonagy and Tobias Nolte — asked a deceptively simple question: how does betrayal trauma translate into depression and personality difficulties years later?

The answer has real implications for anyone considering therapy after painful relational experiences.

The key finding: trauma acts through the mind’s adaptations

The researchers measured betrayal trauma experienced in childhood and in adulthood, and looked at two present-day outcomes: depressive symptoms and the severity of personality difficulties (using the modern, dimensional ICD-11 model). Crucially, they also measured two psychological processes:

The result was striking. Once these two processes were taken into account, the direct link between trauma and adult symptoms disappeared. Betrayal trauma was connected to depression and personality difficulties almost entirely through dissociation and hypomentalizing.

Mentalizing: the mind’s most important casualty

Across every model the researchers tested, hypomentalizing was a stronger pathway than dissociation — for both childhood and adulthood trauma, and for both depression and personality difficulties. In other words: the single most consequential thing betrayal trauma does may be undermining our capacity to understand ourselves and others in terms of feelings, needs and intentions.

This makes painful sense. Mentalizing develops inside relationships of trust. When those very relationships become the source of harm, learning to read minds becomes dangerous — sometimes it feels safer not to know what the other person thinks, or what you yourself feel. What once protected you later becomes the engine of loneliness, confusion and emotional dysregulation.

Adult betrayal hurts too — and the data show it

One finding deserves special attention. We often assume childhood trauma matters most, and adult experiences somehow “should” be easier to absorb. Yet in this study, betrayal trauma experienced in adulthood showed a stronger overall association with current depression than childhood trauma — and an equally strong association with personality difficulties.

If you have been betrayed as an adult — by a partner, a close friend, someone you built your life around — this research validates what you may already feel: it is not “just a bad experience to get over.” Recent betrayal can be emotionally raw, unintegrated, and can activate older vulnerabilities. The two are often connected: people hurt early in life are, sadly, more likely to be hurt again later — a pattern known as revictimization.

What this means for therapy

If trauma harms us largely through dissociation and the collapse of mentalizing, then good trauma therapy cannot stop at retelling the story of what happened. It needs to work on the processes themselves:

This is also why a thorough assessment of relational trauma — in childhood and adulthood — is a standard part of how we understand each person who comes to trauma therapy at our practice.

Simple takeaways — going beyond the study

What follows is no longer part of the research findings. These are our own reflections as clinicians — how we read this study through the lens of everyday therapeutic work with adults.

Feeling numb is an adaptation, not a defect

If after betrayal you feel emotionally “switched off,” detached, or strangely calm — that is likely the same protective mechanism the study measured as dissociation. It once kept you functioning. The goal of therapy is not to judge it, but to make it gradually unnecessary.

“I don’t know what I feel” is part of the injury

Chronic confusion about your own emotions and other people’s intentions is not a personal failure or lack of intelligence. It is what hypomentalizing looks like from the inside — and it is precisely the capacity that therapy can help rebuild.

You don’t have to relive every detail for therapy to work

If symptoms are carried mostly by present-day processes — how you feel, reflect and trust — then the most important work happens in the here and now: noticing emotions in the session, staying with them safely, making sense of them together. The past is understood; the change happens in the present.

Take adult betrayal seriously

An affair, a friend’s deception, exploitation by someone you relied on — people often tell themselves “it shouldn’t affect me this much, I’m an adult.” The data suggest otherwise. Recent betrayal is a legitimate reason to seek help, not something to simply push through.

Struggling to trust your therapist is expected — and workable

If your trust was broken by people close to you, some wariness toward a therapist is a natural extension of the wound. Naming it openly in the session is not a problem in therapy — it often is the therapy.

One capacity, many benefits

Because mentalizing was linked to both depression and personality-level difficulties, strengthening it may pay off across many areas at once — mood, relationships, self-understanding. It is one of the few “levers” in psychotherapy that seems to move several things at the same time.

Source: Jańczak, M. O., Gagliardini, G., Kamza, A., Colli, A., Fonagy, P., & Nolte, T. (2026). Betrayal trauma and adult mental health: The role of mentalizing and dissociation. PLOS ONE, 21(7), e0353662. https://doi.org/10.1371/journal.pone.0353662 (open access). This article is an educational summary and does not replace individual psychological assessment.