Megan H. W. Preece

The contribution of pre-existing depression to the acute cognitive sequelae of mild traumatic brain injury

Primary objective: To determine the effect of pre-existing depression on the cognitive sequelae of mild traumatic brain injury (mTBI) within 24 hours of injury. Research design: A 2 × 2 between-subjects design was used to examine the effect of depression and injury type on neuropsychological test performance. The independent variables were the injury type (mTBI or control) and the presence of depression (depressed or not depressed). Methods and procedures: Participants who had sustained mTBI (30 with depression, 30 without depression) within the previous 24 hours and control participants (19 with depression, 30 without depression) were assessed on the Digit Symbol Substitution Test (DSS), Hopkins Verbal Learning Test (HVLT) and the Speed of Comprehension Test. Results: Participants with mTBI performed worse than controls on the tests, particularly HVLT delayed recall and DSS total correct. Participants with depression did not perform worse than participants without depression. However, there was a significant univariate interaction for HVLT recognition, participants who had sustained mTBI and were classified in the depressed group exhibited worse recognition compared to mTBI participants without depression. Conclusions: The results indicate that depression may interact with mTBI to impair word recognition during the acute phase after a head injury.

Return-to-driving expectations following mild traumatic brain injury

Aim: Although individuals recovering from mild traumatic brain injury (MTBI) could pose a risk to road safety, little is known about their intentions regarding return-to-driving. Reported are the expectations of a sample of emergency department patients with MTBI regarding their recovery and return-to-driving. Method: Eighty-one patients with MTBI were recruited from an emergency department. Participants completed an 11-item questionnaire measuring expectations regarding recovery from injury; five of the items addressed return-to-driving. Results: Only 48% of the sample intended to reduce their driving following their injury. However, those that did intend to reduce their driving nominated a mean duration of 16.59 days (SD = 31.68) of reduced exposure. A logistic regression found that previous head injury experience and an interaction between pain and previous head injury experience predicted intentions to reduce driving. Similarly, a multiple regression revealed that pain level contributed significantly to the variance in time estimates of return-to-driving. Conclusion: The finding that half the individuals recovering from MTBI do not intend to moderate their driving exposure post-injury is cause for concern, as another study has shown that driving performance is compromised in this group immediately after injury.

Memory systems involved in professional skills: A case of dense amnesia due to herpes simplex viral encephalitis

JL, a 25-year-old physiotherapist, became densely amnesic following herpes simplex viral encephalitis (HSVE), causing bilateral damage to medial and ventral areas of her frontal and temporal lobes and their associated circuitry. Three years post-onset, her WAIS-R full scale IQ (Verbal 74, Performance 102) showed an estimated loss of ± 50 points. She displayed severe global amnesia and markedly impaired social cognition. However, her immediate memory, perceptual priming, and cognitive problem-solving abilities were relatively spared. Her retention of professional skills was assessed using simulated physiotherapy scenarios. JL was able to demonstrate some procedural skills spontaneously, but was unable to apply them precisely and flexibly to individual patient needs. She showed no memory of theoretical or propositional physiotherapy knowledge, and could neither plan treatment nor reason clinically. Her performance was well below that of four other physiotherapists who had also not practised for 4 years. Thus, despite the relative sparing of her implicit memory, JLs performance lacked the co-ordinated operation of declarative and implicit long-term memory and the links to working memory that are necessary for the flexible performance of complex professional procedures.

Do self-reported concussions have cumulative or enduring effects on drivers’ anticipation of traffic hazards?

Abstract Aim: To investigate the cumulative effect of multiple self-reported concussions and the enduring effect of concussion on drivers’ hazard perception ability. It was hypothesized: (1) that individuals reporting multiple previous concussions would be slower to anticipate traffic hazards than individuals reporting either one previous concussion or none; and (2) that individuals reporting a concussion within the past 3 months would be slower to anticipate traffic hazards than individuals reporting either an earlier concussion or no prior concussion. Method: Two hundred and eighty-two predominantly young drivers (nconcussed = 68, Mage = 21.57 years, SDage = 6.99 years, 66% female) completed a validated hazard perception test (HPT) and measures of emotional, cognitive, health and driving status. Results: A one-way analysis of variance showed that there was no significant effect of concussion number on HPT response times. Similarly, pairwise comparisons showed no significant differences between the HPT response times of individuals reporting a concussion within the previous 3 months, individuals reporting an earlier concussion and the never concussed group. Conclusion: The findings suggest that previous concussions do not adversely affect young drivers’ ability to anticipate traffic hazards; however, due to reliance on self-reports of concussion history, further prospective longitudinal research is needed.