Post-concussion syndrome
Though no universally accepted definition of postconcussive syndrome exists, most of the literature defines the syndrome as the development of at least 3 of the following symptoms: headache, dizziness, fatigue, irritability, impaired memory and concentration, insomnia, and lowered tolerance for noise and light. One complication in diagnosis is that symptoms of PCS also occur in people who have no history of head injury, but who have other medical and psychological complaints. In one study 64% of people with TBI, 11% of those with brain injuries, and 7% of those with other injuries met the DSM-IV criteria for post-concussion syndrome. Many of these PCS sufferers were misdiagnosed as having other unrelated conditions due to commonality of symptoms. (see diagnosis, below).
Post-traumatic amnesia
There is a significant link between individuals currently suffering from PTA and their performance on the Wechsler Adult Intelligence Scale (WAIS). The scores of those currently experiencing an episode of PTA were compared to individuals who had previously suffered a traumatic brain injury resulting in PTA. Those still suffering from PTA performed significantly worse on both the performance and the verbal subscales of the WAIS. Also, people in early stages of PTA have substantial impairment to anterograde memory function. For example, in the case report of a patient referred to as "JL", Demery et al. noted that his memory impairments were so severe following his injury that he had forgotten that he had attended a Major League Baseball game less than 30 minutes after returning to the center where he was being treated.