common condition associated with PCS is headache. While most people have headaches of the same type they experienced before the injury, people diagnosed with PCS often report more frequent or longer-lasting headaches. Between 30% and 90% of people treated for PCS report having more frequent headaches and between 8% and 32% still report them a year after the injury. Dizziness is another common symptom reported in about half of people diagnosed with PCS and is still present in up to a quarter of them a year after the injury. Older people are at especially high risk for dizziness, which can contribute to subsequent injuries and higher rates of mortality due to falls. About 10% of people with PCS develop sensitivity to light or noise, about 5% experience a decreased sense of taste or smell, and about 14% report blurred vision. People may also have double vision or ringing in the ears, also called tinnitus. 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 PCS may also be exacerbated by, chronic pain, or an interaction of some or all of these. The majority of experts believe that PCS results from a mix of factors, including preexisting psychological factors and those directly relating to the physical injury. It is not known what causes PCS to occur and persist, or why some people who have a mild traumatic brain injury later develop PCS while others do not. The nature of the syndrome and the diagnosis itself have been the subject of intense debate since the 19th century. However, certain risk factors have been identified; for example, preexisting