The effect of traumatic brain injury on sustained attention and working memory

Abstract

Primary objective: The aim of the study was to evaluate working memory (WM) and sustained attention (SA) following severe traumatic brain injury (TBI).

Research design: The study was a quasi-experimental design with two dependent measures.

Methods and procedures: Nine individuals with severe TBI and nine non-injured controls completed two visual tasks containing alphabetic stimuli: a WM task (2-back task) and a 10-minute SA task.

Main outcomes and results: Participants with TBI had lower hit rates and higher false alarm rates than controls on the WM task. Quantitative analysis of the group data did not reveal a differential deficit in SA; however, post-hoc qualitative visual analysis of individual data revealed considerable variability in four participants with TBI, indicating evidence of impaired SA in select individuals. The hit rates for both tasks were positively correlated, supporting the contention that WM and SA are inter-related.

Conclusions: This study provides further evidence of WM deficits following TBI as well as possible SA deficits in some individuals. The results also suggest that WM and SA are inter-related processes. Future studies are needed to replicate the results with larger sample sizes. Based on these findings, patients with TBI may present with WM and SA deficits.

• Vigilance
• 2-back task

Notes

Notes

1. A modified version of the SART referred to as the fixed sequence SART was introduced by Manly et al. [24]. This version varies from the original SART in that numbers are presented in a predictable sequential manner rather than randomly. Rules are otherwise the same in that the participant responds to all non-targets and withholds a response to targets.

2. Many previous studies have used task lengths between 6–45 minutes [9],[14],[15]. Arguably, it is safer to choose as long a task length as possible in order to ensure that the normal vigilance decrement is crossed. However, with a significantly long task length there is risk of jeopardizing subject participation due to the monotonous length of time required to participate in the study. Based on previous literature regarding sustained attention in TBI, 10 minutes was chosen as a compromise to ensure that subject participation was not jeopardized.

3. The purpose of distracters was to ensure that subjects recalled the specific sequential position of each letter. Without distracters it is conceivable that subjects could have simply recalled the recent presentation of a letter and, therefore, judged that it was likely to be a target, without actually recalling that the letter was specifically 2-back.