Post-Traumatic Stress Disorder (PTSD) is a mental health condition that develops after an individual experiences or witnesses a traumatic event, such as a natural disaster, serious accident, combat exposure, or physical assault. The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) defines PTSD by outlining specific symptom patterns required for a diagnosis. The commonly cited “17 symptoms” are organized into four distinct clusters, and a specific number of symptoms from each cluster must be present for a clinical diagnosis.
Intrusion Symptoms
Intrusion symptoms involve the involuntary re-experiencing of the traumatic event, which is profoundly distressing and disruptive. This cluster contains five specific criteria, only one of which must be present for a diagnosis.
The re-experiencing often takes the form of recurrent, involuntary, and intrusive distressing memories of the event. These memories feel like they are breaking into the person’s current consciousness, bringing the original emotional intensity. Individuals also frequently experience recurrent distressing dreams or nightmares directly related to the trauma.
Dissociative reactions, commonly known as flashbacks, are another form of intrusion where the individual feels or acts as if the traumatic event is happening again. Flashbacks can range from brief mental images to a complete loss of awareness of the present surroundings.
A person may also experience intense or prolonged psychological distress when exposed to internal or external cues that symbolize or resemble an aspect of the traumatic event. This distress is often paired with marked physiological reactions to these same cues. For instance, encountering a loud noise might trigger physical symptoms like a racing heart or rapid breathing, signaling the body’s persistent state of alert.
Avoidance Symptoms
Avoidance symptoms reflect the active effort to steer clear of anything associated with the trauma to minimize distress. This cluster contains two specific items, and at least one must be present for a clinical diagnosis. This pattern of avoidance can significantly limit a person’s life.
Avoidance involves internal reminders, such as avoiding distressing memories, thoughts, or feelings about the traumatic event. This attempt to suppress the mental experience often consumes significant mental energy. Individuals also engage in the avoidance of external reminders, including people, places, conversations, or situations that arouse distressing memories.
For example, a person who experienced a car accident might avoid driving or the specific intersection where the event occurred. While initially a coping mechanism, this avoidance can lead to isolation and impairment in daily life.
Negative Changes in Cognitions and Mood
Negative changes in cognitions and mood represent a cluster of seven specific symptoms reflecting persistent negative thoughts and emotional alterations that began or worsened after the trauma. At least two of these seven symptoms are required for a diagnosis. These alterations involve a shift in fundamental beliefs about oneself and the world.
One common symptom is the inability to recall key aspects of the traumatic event, often called dissociative amnesia. This is a psychological defense mechanism where the mind blocks out parts of the memory. The trauma can also lead to persistent and exaggerated negative beliefs or expectations about oneself, others, or the world, such as believing “I am bad” or “The world is completely dangerous.”
Distorted cognitions about the cause or consequences of the event often lead the individual to blame themselves or others. This self-blame is frequently accompanied by a persistent negative emotional state, including feelings like fear, horror, anger, guilt, or shame. These emotions become dominant and pervasive.
A person may also experience a diminished interest or participation in significant activities that were once enjoyable. This loss of interest is often coupled with feelings of detachment or estrangement from others, leading to isolation. Finally, a persistent inability to experience positive emotions, such as happiness or satisfaction, contributes to emotional numbing.
Changes in Arousal and Reactivity
Changes in arousal and reactivity describe symptoms related to a chronic state of heightened alertness and altered physical responses. This cluster contains six specific symptoms, of which at least two must be present for a diagnosis. These symptoms indicate an overactive sympathetic nervous system, keeping the individual prepared for danger.
One manifestation is irritable behavior and angry outbursts, often expressed as verbal or physical aggression. This heightened emotional state can be coupled with reckless or self-destructive behavior, such as driving dangerously fast or engaging in substance misuse.
A constant feeling of being “on guard” is known as hypervigilance, where the person excessively monitors their environment for signs of threat. This is often paired with an exaggerated startle response, causing the person to react strongly to sudden, unexpected stimuli. This response reflects the body’s readiness for a fight-or-flight reaction.
Chronic stress also affects cognitive functions, leading to problems with concentration and difficulty focusing on tasks. Sleep disturbance is also common, manifesting as difficulty falling or staying asleep. These arousal symptoms collectively maintain a state of physical and mental exhaustion.
The Context for Clinical Diagnosis
A clinical diagnosis requires meeting several additional criteria established by the DSM-5 beyond the four symptom clusters.
Criterion A: Traumatic Exposure
The first requirement is exposure to a traumatic event. This exposure must involve actual or threatened death, serious injury, or sexual violence, and must be experienced in one of the following ways:
- Experienced directly.
- Witnessed.
- Learned about happening to a close loved one.
- Involving repeated exposure to aversive details, such as in professional duties.
The required symptoms must be present for a period of more than one month (Criterion F). Symptoms lasting less than a month may indicate Acute Stress Disorder. This duration requirement distinguishes a temporary stress reaction from a persistent mental health condition.
The symptoms must also cause clinically significant distress or impairment in social, occupational, or other important areas of functioning (Criterion G). This means the symptoms are severe enough to interfere with the person’s ability to live a normal life. A diagnosis also requires a clinician to rule out substance use or another medical condition as the primary cause of the symptoms (Criterion H).