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Post-traumatic stress disorder is a treatable mental health condition that arises following exposure to traumatic events. In personal injury litigation, it is one of the most commonly claimed psychiatric injuries. The court requires rigorous assessment, not merely the claimant’s account of their symptoms. A proper expert diagnosis demands objective evidence, structured diagnostic criteria, and consideration of alternative explanations, including feigning.
Diagnostic criteria: ICD-11 and DSM-5-TR
PTSD is formally defined in two major diagnostic classification systems used internationally and in the UK:
ICD-11 (WHO International Classification of Diseases, 11th edition) defines PTSD as a disorder that can develop following exposure to an extremely threatening or horrific event or series of events. Core diagnostic features include:
- Re-experiencing of the traumatic event in the present (intrusive memories, flashbacks, or nightmares).
- Avoidance of reminders of the traumatic event (avoiding thoughts, conversations, places, people, activities or situations related to the event).
- Persistent pervasive sense of current threat (hypervigilance, exaggerated startle response, irritability or aggressive behaviour).
ICD-11 also defines Complex PTSD (CPTSD), which includes the above features plus disturbances in self-organisation: persistent disturbance of mood and self-perception, negative self-regard, and persistent difficulties in relationships.
DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision, American Psychiatric Association) defines PTSD as involving exposure to actual or threatened death, serious injury or sexual violence, followed by intrusive symptoms, avoidance, negative alterations in cognitions and mood, and hyperarousal symptoms. For diagnosis, symptoms must be present for at least one month and cause clinically significant distress or functional impairment.
NICE guideline NG116 (Post-traumatic stress disorder) reflects UK clinical practice and endorses assessment using these criteria, along with structured questioning about re-experiencing, avoidance, hyperarousal, dissociation and negative alterations in mood and thinking.
Symptoms and presentation
PTSD symptoms: re-experiencing (intrusive memories, flashbacks, nightmares); avoidance (of thoughts, places, reminders); hyperarousal (poor concentration, startle, irritability, anger); negative mood/cognition (negative beliefs, emotional numbing, detachment, guilt); dissociation (depersonalisation, derealisation). NICE guidance emphasises heterogeneous presentations; not all patients experience all symptoms. Assessment requires structured questioning on each domain.
Why self-report is insufficient
Experts must go beyond accepting the claimant’s account. Assessment includes: corroboration (GP, hospital, employer records); consistency across time (symptoms stable, worsened or improved?); behaviour observation (does demeanour match reports?); functional impact (detailed work, relationship, sleep impairment); premorbid history (prior mental health, family history). Discrepancies between account and records, or between reported and observed symptoms, require exploration.
Malingering and symptom validity testing
Malingering is the intentional production of false psychiatric symptoms for secondary gain (e.g. compensation). The expert must be alert to red flags:
- Symptom presentation that is textbook or stereotyped (matching a description of PTSD from the internet or media).
- Sudden onset of severe symptoms in a person with previously stable mood.
- Inconsistencies between reported symptoms and objective findings.
- Symptoms that worsen predictably at times when compensation is being discussed, or improve suddenly when a settlement is agreed.
- Inconsistent history given on repeated interviews or to different professionals.
Symptom validity testing (SVT) is an objective psychometric tool used to detect feigning or gross exaggeration. Common tests include the Test of Memory Malingering (TOMM) or the Validity Indicator Profile (VIP). These tests are deliberately easy; a person with genuine PTSD will pass them easily, while someone feigning memory problems or cognitive impairment will perform worse than chance. If SVT indicates insufficient effort or inconsistent responding, the expert reports this to the court.
However, the expert must not assume malingering from poor SVT performance alone. Some patients with severe dissociation or genuine cognitive symptoms may perform unexpectedly poorly. Context matters.
Assessment methodology
A rigorous assessment includes: structured interview using standardised tools (CAPS-5, PCL-5, IES-R); timeline of symptoms; review of GP/hospital records and sick notes; occupational history and functional impact; treatment history and response to evidence-based therapy (TF-CBT, prolonged exposure per NICE); collateral information from family, employers, or treating clinicians.
Prognosis and treatment
PTSD is treatable; NICE recommends trauma-focused CBT or prolonged exposure as first-line. For the court, the expert addresses: likelihood of recovery (uncomplicated PTSD: ~30-40% spontaneous remission untreated within one year; higher with treatment; complex PTSD: worse prognosis, longer duration); treatment engagement and response; chronicity (recovery timescales vary); prognosis statement (likely resolution, persistence, or permanent symptoms). Persistent symptoms justify damages for future loss and ongoing therapy costs.
What a court report must address
An expert psychiatric report on PTSD for personal injury litigation should cover:
- Diagnostic conclusion: Is PTSD or complex PTSD present, with reference to ICD-11/DSM-5-TR criteria?
- Causal link: Is the PTSD causally related to the traumatic event (the accident/assault) at issue, or is it attributable to pre-existing mental illness or other factors?
- Differential diagnosis: Have other psychiatric conditions (depression, anxiety disorder, adjustment disorder) been considered and excluded?
- Severity and functional impairment: Using standardised measures, quantify the severity of PTSD and document its impact on work, relationships and daily living.
- Treatment recommendations: What psychological or pharmacological treatment is indicated? Is the claimant currently receiving appropriate treatment?
- Prognosis: Expected course of illness and likelihood of recovery, with timescale.
- Damages: Although not the expert’s role to calculate damages (that is for the court), the expert may comment on expected duration of symptoms and likely need for ongoing treatment, informing the quantification of future loss.
Key points
- PTSD is diagnosed using ICD-11 or DSM-5-TR criteria, which require re-experiencing, avoidance, hyperarousal and negative mood/cognition.
- Self-report alone is insufficient; the expert must corroborate the history using medical records, occupational history and collateral information.
- Malingering and symptom exaggeration must be considered; symptom validity testing is a useful objective tool.
- PTSD is treatable; NICE recommends trauma-focused cognitive behavioural therapy or prolonged exposure therapy.
- Prognosis varies: uncomplicated PTSD often improves within one year with treatment; complex PTSD has a longer trajectory.
- The court report must address diagnosis, causal link, severity, treatment and prognosis with reference to objective findings and standardised measures.
Related: Find a medico-legal expert