PCS may cause insomnia, fatigue, or other problems with sleep. Psychological and behavioral
Psychological conditions, which are present in about half of people with PCS, may include irritability, anxiety, depression, and a change in personality. Other emotional and behavioral symptoms include restlessness, aggression, and mood swings. Some common symptoms, such as apathy, insomnia, irritability, or lack of motivation, may result from other co-occurring conditions, such as depression. Higher mental functions
Common symptoms associated with a diagnosis of PCS are related to cognition, attention, and memory, especially short-term memory, which can also worsen other problems such as forgetting appointments or difficulties at work. In one study, one in four people diagnosed with PCS continued to report memory problems a year after the injury, but most experts agree that cognitive symptoms clear within six months to a year after injury in the vast majority of individuals. Causes
The question of the cause or causes of PCS has been heavily debated for many years and remain controversial. It is not known to exactly what degree the symptoms are due to physiological changes or to other factors, such as pre-existing psychiatric disorders or factors related to secondary gain or disability compensation. The subjectivity of the complaints complicates assessment and makes it difficult to determine whether symptoms are being exaggerated or feigned.PCS may also be exacerbated by psychosocial factors, chronic pain, or an interaction of some or all of these.
The idea that this set of symptoms forms a distinct entity began to attain greater recognition in the latter part of the 19th century. John Erichsen, a surgeon from London, played an important role in developing the study of PCS. The controversy surrounding the cause of PCS began in 1866 when Erichsen published a paper about persisting symptoms after sustaining mild head trauma. He suggested that the condition was due to "molecular disarrangement" to the spine. The condition was originally called "railroad spine" because most of the injuries studied had happened to railroad workers. While some of his contemporaries agreed that the syndrome had an organic basis, others attributed the symptoms to psychological factors or to outright feigning. In 1879, the idea that a physical problem was responsible for the symptoms was challenged by Rigler, who suggested that the cause of the persisting symptoms was actually "compensation neurosis": the railroads practice of compensating workers who had been injured was bringing about the complaints. Later, the idea that hysteria was responsible for the symptoms after a mild head injury was suggested by Charcot. Controversy about the syndrome continued through the 20th century. During World War I many soldiers with puzzling symptoms after being close to a detonation but without any evidence of a head wound. The illness was called shell shock, and a psychological explanation was eventually favoured. By 1934 the current concept of PCS had replaced ideas of hysteria as the cause of post-concussion symptoms.