Intrusion symptoms (≥ 1 of the following): Having recurrent, involuntary, intrusive, disturbing memories Having recurrent disturbing dreams (eg, nightmares) of the event Acting or feeling as if the event were happening again, ranging from having flashbacks to completely losing awareness of the present surroundings Feeling intense psychologic or physiologic distress when reminded of the event (eg, by its anniversary, by sounds similar to those heard during the event) Avoidance symptoms (≥ 1 of the following): Avoiding thoughts, feelings, or memories associated with the event Avoiding activities, places, conversations, or people that trigger memories of the event Negative effects on cognition and mood (≥ 2 of the following): Memory loss for significant parts of the event (dissociative amnesia) Persistent and exaggerated negative beliefs or expectations about oneself, others, or the world Persistent distorted thoughts about the cause or consequences of the trauma that lead to blaming self or others Persistent negative emotional state (eg, fear, horror, anger, guilt, shame) Markedly diminished interest or participation in significant activities A feeling of detachment or estrangement from others Persistent inability to experience positive emotions (eg, happiness, satisfaction, loving feelings) Altered arousal and reactivity (≥ 2 of the following): Difficulty sleeping Irritability or angry outbursts Reckless or self-destructive behavior Problems with concentration Increased startle response Hypervigilance In addition, manifestations must cause significant distress or significantly impair social or occupational functioning and not be attributable to the physiologic effects of a substance use or another medical disorder.