Classification & Assessment in Psychiatry · Paper A
PTSD (diagnostic criteria)
PTSDPost-traumatic stress disorder, a condition triggered by experiencing or witnessing a traumatic event.Read more → (post-traumatic stress disorder) is a lasting reaction to a terrifying event. For example, imagine a patient who was involved in a serious road accident and, months later, still has vivid flashbacks and jumps at loud noises. That combination of re-experiencing and hyperarousal, persisting well past a month, is what separates PTSD from a normal short-term stress reaction. In practice, this means always checking symptom duration before diagnosing PTSD rather than a normal, time-limited stress response.
PTSDPost-traumatic stress disorder, a condition triggered by experiencing or witnessing a traumatic event.Read more → follows exposure to actual or threatened death, serious injury or sexual violence. The core symptom clusters are: re-experiencing (intrusive memories, nightmares, flashbacks), avoidance (of reminders), hyperarousal (jumpiness, exaggerated startle, poor sleep), and, in DSM-5, negative changes in thinking and mood. Symptoms must last more than one month; shorter reactions suggest an acute stress reaction. Picture a patient with vivid flashbacks and hyperarousal only two weeks after a road traffic accident. Practically, the one-month duration is the specific line that separates a normal, expected reaction from a diagnosable disorder.
A fresh doctor might assume anyone who lives through something terrifying will develop lasting psychological problems, and that treating the two as the same thing is safe. It is not: most people recover from a frightening event within weeks without any disorder, and (post-traumatic stress disorder) exists specifically to mark the smaller group whose reaction persists, intensifies, and starts to look like a specific, recognisable pattern rather than ordinary distress fading over time. Hold the word PERSISTS through every section below, because duration is the single feature that most often separates PTSD from a normal stress response in an exam vignette.
is a disorder that can follow exposure to an event involving actual or threatened death, serious injury, or sexual violence (the TRAUMA criterion), producing four symptom clusters: re-experiencing (intrusive memories, nightmares, flashbacks), avoidance (of people, places, or thoughts linked to the trauma), a persistent sense of current threat or hyperarousal (exaggerated startle, poor sleep, irritability, hypervigilance), and, in DSM-5 (the American Psychiatric Association's Diagnostic and Statistical Manual, 5th edition), negative changes in mood and thinking. Symptoms must last more than one month, and cause real distress or functional impairment.
A common mistake is diagnosing immediately after a traumatic event. Symptoms lasting under a month, however severe, are more likely to represent an acute stress reaction, which is expected to settle without necessarily becoming a lasting disorder. The one-month threshold is the specific line an exam question is usually testing: a vignette describing vivid flashbacks two weeks after a road traffic accident is testing whether the candidate correctly withholds a PTSD diagnosis until that threshold is crossed.
Not everyone exposed to the same trauma develops , because the disorder isn't simply "proportional distress": it reflects a specific failure of normal fear-memory processing, where the traumatic memory stays fragmented and easily triggered instead of being consolidated into an ordinary, contextualised past memory. That is why the same car crash can leave one person with brief, resolving distress and another with vivid, intrusive re-living months later: the clusters below describe what happens when that processing goes wrong.
Re-experiencing is the cluster most people picture when they hear : unwanted intrusive memories, nightmares replaying the event, and flashbacks (vivid moments where the patient feels as though the trauma is happening again, not just remembering it). For example, a soldier who ducks for cover at a car backfiring, briefly convinced he is back in a warzone, is re-experiencing rather than simply remembering. This cluster is what distinguishes PTSD from ordinary, voluntary recall of a bad memory.
Avoidance covers active efforts to stay away from reminders of the trauma, whether external (avoiding the road where an accident happened) or internal (avoiding thoughts, feelings, or conversations about it). Avoidance can look like simple caution to a patient, but its function is protective in the short term and maintaining in the long term: refusing to drive at all, rather than driving cautiously, keeps the fear from ever being tested and corrected.
The hyperarousal (or current-threat) cluster includes an exaggerated startle response, hypervigilance (constantly scanning for danger), irritability, poor concentration, and disrupted sleep. ICD-11 (the World Health Organization's International Classification of Diseases, 11th revision) frames this cluster as a persistent SENSE OF CURRENT THREAT, capturing the idea that the patient's nervous system behaves as though the danger is still present, long after the actual event has ended.
ICD-11 also recognises complex , which adds disturbances in self-organisation (DSO) on top of the core PTSD symptoms: severe difficulties regulating emotion, a persistently negative self-concept (feeling diminished, defeated, or worthless), and difficulties sustaining relationships and feeling close to others. Complex PTSD typically follows prolonged or repeated trauma from which escape is difficult, such as ongoing childhood abuse or captivity, rather than a single discrete event.
must be distinguished from acute stress reaction (settles within days, not persisting past a month), adjustment disorder (a broader, less trauma-specific reaction to any identifiable stressor, not requiring threat to life), and normal grief (an expected reaction to loss without the specific re-experiencing and avoidance pattern). Depression can coexist with PTSD but lacks the trauma-specific intrusive symptoms that define it.
Diagnosis rests on meeting the trauma-exposure criterion plus a set number of symptoms across each required cluster, persisting beyond one month and causing genuine distress or impairment: this is a structured, criteria-based process, not a judgement based on how upsetting the event sounds. In practice, clinicians support this with structured tools such as the Trauma Screening Questionnaire for initial screening and the Clinician-Administered Scale for a more detailed, criteria-mapped assessment, rather than relying on an unstructured conversation alone.
NICE (the National Institute for Health and Care Excellence) recommends trauma-focused psychological therapy first-line: trauma-focused (cognitive behavioural therapy) or EMDR (eye movement desensitisation and reprocessing), which helps the patient process the traumatic memory rather than only manage symptoms. Routine single-session psychological debriefing immediately after trauma is not recommended, since some evidence suggests it can be unhelpful. Benzodiazepines are generally discouraged because they do not treat the underlying processing problem and carry dependence risk; medication, where used, plays a secondary role to trauma-focused therapy.
Vignettes frequently describe classic re-experiencing and hyperarousal symptoms very soon after a trauma and expect the candidate to correctly identify an acute stress reaction rather than jumping to before one month has passed. Another trap conflates ordinary sad or intrusive memories of a difficult event with the specific, involuntary, trauma-linked flashbacks and avoidance that PTSD requires.
follows exposure to a threat-to-life event and requires re-experiencing, avoidance, and hyperarousal (plus negative mood changes in DSM-5) persisting beyond one month; ICD-11 adds complex PTSD for prolonged or repeated trauma, and NICE recommends trauma-focused or EMDR as first-line management, with debriefing and routine benzodiazepines both discouraged.