Cognitive recovery after severe head injury. 3. WAIS verbal and performance IQs as a function of post-traumatic amnesia duration and time from injury.

Two studies are reported are reported in which severely head-injured patients were followed up and Verbal (VIQ) and Performance (PIQ) IQs obtained on the Wechsler Adult Intelligence Scale at four intervals after injury. In the first study 51 patients were systematically followed, and results were based upon serial testing. In the second study results were based on the earliest data available from an additional 98 patients who had not been followed so systematically, in order to introduce a control for the effects of practice. Patients in both studies were categorised into four groups of the severity of head injury based upon duration of post-traumatic amnesia (PTA). In both studies, VIQ level was found to be related to PTA duration at three months after injury, while PIQ was related to PTA duration at both three and six months. No such relationships were found at 12 and 30 months after injury. Results are discussed in the context of previous studies relating the outcome of head injury to the duration of PTA.