“…Cairns (1942), Russell (1943), Russell (1959), Lewin (1966) and Jennett (1976), it was found that the duration of disability after a concussive head injury was closely related to the length of PTA. Kay et al (1971), in a retrospective study of hospitalized head injury patients, were unable to correlate the duration of loss of consciousness, or PTA, with the presence or absence of post-concus sional symptoms when the patients were re viewed between 3 and 6 months after injury, stating that (a combination of) 'marital state, social class, type of accident and previous psychiatric illness' yielded a much better cor relation. However, their study did not distin guish between the post-concussional state on the one hand and the socially determined sta tes, especially AN, in which the patient's com plaints suggest the post-concussional syndrome but there is no correlation with the severity of injury.…”