Posttraumatic stress disorder (PTSD) is a mental disorder that can develop following exposure to a traumatic event. Historically, it has been debated whether features of this disorder derive from mental or brain organic changes. Recent developments in neuroimaging and biological studies suggest a biological background of PTSD. In contrast, recent literature shows an impact of psychological context in the traumatic experiences, and concepts such as "moral injury" have been developed. Future studies are needed to better understand the mental and organic mechanisms underlying PTSD.