Post-traumatic stress disorder (PTSD) results after experiencing or witnessing a terrifying event which later leads to mental health problems. This disorder has always existed but has only been recognized as a psychological disorder within the past forty years. Before receiving its official diagnosis in 1980, when it was published in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-lll), Post-traumatic stress disorder was more commonly known as soldier's heart, irritable heart, or shell shock. Shell shock and war neuroses were coined during World War I when symptoms began to be more commonly recognized among many of the soldiers that had experienced similar traumas. By World War II, these symptoms were identified as combat stress reaction or battle fatigue. In the first edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-I), post-traumatic stress disorder was called gross stress reaction which was explained as prolonged stress due to a traumatic event. Upon further study of this disorder in World War II veterans, psychologists realized that their symptoms were long-lasting and went beyond an anxiety disorder. Thus, through the effects of World War II, post-traumatic stress disorder was eventually recognized as an official disorder in 1980. General overview Changing terminology Nostalgia, soldier's heart, and railway spine The term nostalgia was first coined in 1761 when soldiers reported feeling homesick, sleep disturbances, and anxiety after being in combat. Later, soldier's heart was used to describe these symptoms but instead blamed cardiac problems as the source of anxiety and overstimulation. Railway spine also explained physical causes for PTSD symptoms. After railroad accidents became more common, the victims of these accidents exhibited emotional distress. Shell shock and war neuroses Before the term post-traumatic stress disorder was established, people that exhibited symptoms were said to have shell shock or war neuroses. This terminology came about in WWI when a commonality among combat soldiers was identified during psychiatric evaluations. These soldiers all appeared to be in a catatonic state following battle, or "shocked by shells", hence the term shell shocked. Battle fatigue and combat stress reaction During World War II, the diagnosis for shell shock was replaced with combat stress reaction. These diagnoses resulted from soldiers being in combat for long periods of time. There was some skepticism surrounding this diagnosis as some military leadership, including George S. Patton did not believe "battle fatigue" to be real. Yet, due to evolving practices,