Systematic Variation of the Severity of Motor Vehicle Accident-Related Traumatic Brain Injury Vignettes Produces Different Post-Concussion Symptom Reports

Abstract

This study investigated the specificity of the post-concussion syndrome (PCS) expectation-as-etiology hypothesis. Undergraduate students (n = 551) were randomly allocated to one of three vignette conditions. Vignettes depicted either a very mild (VMI), mild (MI), or moderate-to-severe (MSI) motor vehicle-related traumatic brain injury (TBI). Participants reported the PCS and PTSD symptoms that they imagined the depicted injury would produce. Secondary outcomes (knowledge of mild TBI, and the perceived undesirability of TBI) were also assessed. After data screening, the distribution of participants by condition was: VMI (n = 100), MI (n = 96), and MSI (n = 71). There was a significant effect of condition on PCS symptomatology, F(2, 264) = 16.55, p < .001. Significantly greater PCS symptomatology was expected in the MSI condition compared to the other conditions (MSI > VMI; medium effect, r = .33; MSI > MI; small-to-medium effect, r = .22). The same pattern of group differences was found for PTSD symptoms, F(2, 264) = 17.12, p < .001. Knowledge of mild TBI was not related to differences in expected PCS symptoms by condition; and the perceived undesirability of TBI was only associated with reported PCS symptomatology in the MSI condition. Systematic variation in the severity of a depicted TBI produces different PCS and PTSD symptom expectations. Even a very mild TBI vignette can elicit expectations of PCS symptoms.

Keywords:

• Mild traumatic brain injury
• Expectation-as-etiology
• Neurobehavioral Symptom Inventory
• Post-traumatic stress disorder

Acknowledgements

The Human Research Ethics Committee of Queensland University of Technology (QUT-HREC #1000000311) approved this research. This project was granted an occupational workplace health and safety clearance. Funding for this project was provided by the School of Psychology and Counselling, Queensland University of Technology. The authors would like to thank Lauren Cunningham who was employed as a research assistant on this project.

Notes

¹ Note that Mulhern and McMillan (2006) wrote that they assessed undesirability of the “four conditions” that they studied using vignettes (p. 441) one of which was labeled “mild traumatic brain injury”. However, the undesirability data that they report in Table 3 of their article lists these ratings under the heading “head injury” (p. 443). We have assumed that undesirability ratings were related to mTBI, not head injury.

² The age of excluded participants who failed the trap questions or did not comply with task instructions (n = 130; Mdn = 20) did not differ significantly from the participants who were retained in the analyses (n = 267; Mdn = 20), U = 16756.5, z = –.199, p = .852. There was no significant association between whether participants were excluded based on trap question and task compliance failure or whether they were retained for the analyses, x ² (1) = 1.016, p = .313.

³ r can be interpreted as follows: r = .1 small effect, r = .3 medium effect, and r = .5, large effect (Field, 2009).

⁴ Note that King (2011) used different anchors for NSI items (0 to 4); therefore, to facilitate comparison against the recommended cut off, we rescaled the NSI item scores and used these new scores to create a rescaled NSI total score. The rescaled NSI total score was used for this comparison only.