Symptoms of Post-Traumatic Stress Disorder (PTSD) can emerge immediately after a traumatic event, or weeks, months, or even years later. These symptoms can significantly impact an individual's social life, work performance, and personal relationships, leading to serious problems. The symptoms and severity of PTSD vary greatly from person to person.

In individuals with PTSD, volumetric changes may be observed in the hippocampus, the brain region responsible for memory and emotional regulation. This can lead to difficulties in processing traumatic memories, intense feelings of fear and anxiety, memory problems, flashbacks, and nightmares. A dysfunctional hippocampus can prevent such memories from being properly processed and their intensity from decreasing over time.

The main symptoms of PTSD are generally grouped under the following categories:

* Re-experiencing the Traumatic Event (Intrusive Symptoms): This is the feeling of reliving the event through dreams (nightmares) or while awake (flashbacks). This can lead to a sense of detachment from reality, and triggers like a smell, sound, or image can provoke intense anxiety and other severe emotions.
* Avoidance Behaviors: This refers to the conscious effort to stay away from situations, people, places, or thoughts that remind one of the traumatic event. This can restrict a person's daily life activities.
* Negative Alterations in Cognition and Mood: This category includes disinterest in activities or people formerly enjoyed, pessimism about the future, and feelings of alienation and detachment. Additionally, persistent negative beliefs about oneself and the world, as well as feelings like guilt or shame, may be observed.
* Hyperarousal and Reactivity: This manifests as symptoms not seen before the trauma, such as intolerance, sudden outbursts of anger, sleep disturbances, difficulty concentrating, and a constant state of hypervigilance.

Additionally, individuals with PTSD may commonly experience repressed anger, guilt, shame, or feelings of helplessness.