poorer behavioral adjustment before the injury than children with no persistent symptoms; these findings support the idea that PCS may result from a combination of factors such as brain dysfunction resulting from head injury and preexisting psychological or social problems. Different symptoms may be predicted by different factors; for example, one study found that cognitive and physical symptoms were not predicted by the manner in which parents and family members coped with the injury and adjusted to its effects, but psychological and behavioral symptoms were. Brain inflammation is suggested to play a role in post-concussive syndrome. Psychological It has been argued that psychological factors play an important role in the presence of post-concussion symptoms. The development of PCS may be due to a combination of factors such as adjustment to effects of the injury, preexisting vulnerabilities, and brain dysfunction. Setbacks related to the injury, for example problems at work or with physical or social functioning, may act as stressors that interact with preexisting factors such as personality and mental conditions to cause and perpetuate PCS. In one study, levels of daily stress were found to be correlated to PCS symptoms in both concussed subjects and controls, but in another, stress was not significantly related to symptoms. Iatrogenic effects (those caused by the medical intervention) may also occur when individuals are provided with misleading or incorrect information related to recovery of symptoms. This information may cause people to focus and dwell on the idea that their brains are permanently damaged. It appears that even the expectation of symptoms may contribute to the development of PCS by causing individuals with mTBI to focus on symptoms and therefore perceive them to be more intense, to attribute symptoms that occur for other reasons to the injury, and to underestimate the rate of symptoms before the injury. Diagnosis The International Statistical Classification of Diseases and Related Health Problems (ICD-10) and the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders have set out criteria for post-concussion syndrome (PCS) and post-concussional disorder (PCD), respectively. The ICD-10 established a set of diagnostic criteria for PCS in 1992. In order to meet these criteria, a patient has had a head injury "usually sufficiently severe to result in loss of consciousness" and then develop at least three of the eight symptoms marked with a check mark in the table at right under "ICD-10" within four weeks. About 38%