Another study found that although children with PCS had poorer scores on tests of cognitive functioning after the injury, they also had 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.
Couch, Lipton, Stewart and Scher (2007) argue that headaches, one of the hallmarks of PCS, occur in a variety of injuries to the head and neck. Further, Lew et al. (2006) reviewed ample studies comparing headaches to post-traumatic headaches and found that there is wide heterogeneity in the source and causes of headaches. They point out that the International Headache Society lists 14 known causes of headaches, as well. Furthermore, the headaches may be better accounted for by mechanical causes, such as whiplash, which is often mistaken for PCS. An additional possibility is that posttraumatic stress disorder can account for some cases diagnosed as PCS, but for emotional regulation as well.Depression, posttraumatic stress disorder, and chronic pain share symptoms resembling those of PCS. One study found that while people with chronic pain without TBI do report many symptoms similar to those of post-concussion syndrome, they report fewer symptoms related to memory, slowed thinking, and sensitivity to noise and light than people with mTBI do. Additionally, it has been found that neuroendocrinology may account for depressive symptoms and stress management due to irregularities in cortisol regulation, and thyroid hormone regulation. Lastly, there is evidence that major depression following TBI is quite common, but may be better accounted for with a diagnosis of dysexecutive syndrome.In a syndrome, a set of symptoms is consistently present, and symptoms are linked such that the presence of one symptom suggests that of others.