Minor facial, jaw, eye, and neck injuries are also common. To complicate matters further, social and psychological factors that pre-date an injury, as well as circumstances following the trauma, may come into play. Past research has focused primarily on the neuropsychological impairments that are revealed by formal tests and measures. According to the best available information, MHT produces neuropsychological problems characterized by distractibility, reduced ability to sustain and divide attention, slowness in processing information, and reduced ability to learn and retain new information. These difficulties are most pronounced right after an injury and gradually resolve over time.
Recovery typically takes days to weeks.
This has been demonstrated in studies based on consecutive hospital admissions consisting primarily of previously healthy young adults, who constitute the majority of MHT cases. After a year, taken as a whole, they do not differ from control groups composed either of uninjured friends or of people who sustained injuries to parts of their bodies other than their heads. This generalization applies to the majority of cases of MHT, but obviously not to all. An unknown but small fraction of the cases do not follow the normal recovery pattern, a problem discussed elsewhere in this issue. At one year post-injury, people with the mildest of brain injuries perform essentially the same on neuropsychological tests as people who have suffered other bodily injuries only.