"Like people, Elephants can also become victims of past traumas and exhibit symptoms of PTSD years after the experience Post-traumatic stress disorder (PTSD) is a condition that describes anxiety-based responses to life-threatening events.

Traumatic stress is different from other types of stress because the individual’s existence is physically and emotionally threatened and s/he is unable to escape. While environmental threats such as hurricanes can be terrifying, in many cases they appear to cause less ill effects than do human-caused traumas. Victims are usually able to anticipate natural disasters and make attempts to avoid harm. Events or "stressors" that underlie the development of PTSD include threat of death; physical abuse; deprivation; torture; isolation; forced incarceration (captivity); and witnessing the loss, death or threat of death to a loved one. All elephants in captivity have experienced most, if not all, of these events."
— Post-Traumatic Stress and Elephants in Captivity, G.A. Bradshaw Ph.D., Ph.D. & Lorin Lindner Ph.D., M.P.H.

The articles linked below focus on Post Traumatic Stress Disorder in elephants.