A comparison of mildly head-injured, malingering, and non-head-injured adult South Africans : neuropsychological performance and post-concussion symptoms.

Abstract

The study reviews the literature concerning mild head injury and post concussion symptoms. It then investigates the applicability of international findings to South African patients. Three groups of subjects are compared: mildly injured, noninjured, and instructed malingerers. The study establishes base rates of postconcussive symptoms in the noninjured subjects, scores on tests of cognitive ability among the noninjured subjects, expectations regarding postconcussive sequelae among the noninjured subjects, the perceptions of injured subjects of their preand postmorbid status, and relationships between subjectively experienced symptoms and cognitive deficits am.ong injured subjects. Injured subgroups are examined to investigate pre-, peri-, and post-injury factors associated with development of postconcussive complaints. No differences in cognitive performance were found between the injured and noninjured groups. Time since injury did not affect cognitive performance, apart from on a copy task. It was found that injured subjects reported lower pre-injury levels of incidence of symptoms than those reported by noninjured subjects. No differences were found between post-injury reporting of postconcussive complaints and those symptoms reported by noninjured controls. Some postconcussive symptoms were nevertheless found to correlate with certain measures of cognitive performance.

Instructed malingerers responded differently noninjured injured and not injured subjects, reporting fewer pre-injury complaints and mere post-injury complaints. They also performed more poorly on several cognitive measures. Test scores that effectively identified malingerers were then re-examined, and cut-off rates suggested for differentiating malingerers from genuinely injured subjects.