Post-Traumatic Stress

Post-Traumatic Stress Syndrome, shortened to PTSS, formerly known as Post-Traumatic Stress Disorder (PTSD), is a condition of persistent mental and emotional stress occurring as a result of injury or severe psychological shock. It is often received from either a single traumatic event that is witnessed or experienced to a series of enduring events subjected to a long period of time.

Causes and Symptoms
Although every person reacts to trauma differently, victims of PTSS have faced a shocking event or series of events, which include crimes like sexual or physical assaults, the death of a loved one, the effects of natural disasters, and the horrors of war. Symptoms include reliving the ordeal or projecting it in their surrounding environment, the avoiding of people or places that remind them of their traumatic event, increased emotions like fits of anger and sadness that are often triggered, and, in some cases, some depression.

On Criminal Minds
PTSS has referenced multiple times on the show and has been a driving force of criminals and other characters. Until Season Thirteen, it was referred to by its former name, PTSD.

The following characters on the show suffer from PTSS:

Non-Criminal

 * SSA Elle Greenaway had to resign from the BAU after murdering an unsub due to PTSS, which she developed after being shot by Randall Garner.
 * Traumatized after the murder of his girlfriend Sarah Jacobs, Jason Gideon would later abruptly retired from the BAU in Season Three.
 * Tara Rios was tortured and raped alongside another woman by serial killer Johnny Ray Covey. She later escaped but had to live with her ordeal plus the fact she left the other woman behind.
 * After witnessing the murder of her father, hearing the death of her tortured aunt and plus being forced to experience and participate in her abductor, Ellie Spicer would later develop PTSS, later trusting and confiding only in Agent Morgan as she tried to adept to her new life.
 * SSA Dr. Spencer Reid's PTSS began developing from his time in prison after being framed and imprisoned for murder in Mexico.

Criminal

 * Roy Woodridge's severe PTSS mostly stemmed from a single event where he disarmed and killed a child soldier in self-defense. He would later believe he was still in the battlezone when committing his kills, but made sure the children around him were safe.
 * After witnessing his newly-made fiancée Vickie's gang-rape and murder, Jonny McHale's PTSS would lead him to target members of the gang responsible for Vickie's murder.
 * Ian Coakley's PTSS was a contributing factor to his delusions, where an accidental car crash caused by him that resulted in his wife's death was actually an intentional murder by a conjured-up driver.
 * Darrin Call would stay traumatized after witnessing his father's crimes against young boys.
 * Similar to Roy Woodridge, Luke Dolan would develop this mental illness while in the war, specifically when he had to murder two children.
 * Matthew Downs was traumatized after his years as a Marine, which caused him to retaliate against the American government and eventually become a homegrown terrorist.
 * William Taylor suffered from some aspects of PTSS due to the abduction and murder of his daughter Tatiana. Although not fully diagnosed, the alleged PTSS could have been the driving force in his kills.