Background: Some patients with TBI (traumatic brain injury) might go on to manifest attentional deficit in the workplace although they performed well in standard neuro­psychological tests. We, therefore, developed an original paper-and-pencil type dual-task (Oiso DT-A) for assessing inattention. We showed that the Oiso DT-A might be valuable and sensitive for detecting inattention including mild deficit. The task, however, was not applicable for patients with the dominant-hand dysmobility because it included written calculation. The purpose of this study was to investigate the validity of newly developed DT (Oiso DT-B) which could be completed with the non-dominant hand.

Methods: A total of 134 healthy individuals and 36 TBI patients were the subjects. The Oiso DT-B combined visual­ly and audibly presented selective cancellation-tasks. A subject was required to identify and respond to both target stimuli of number 7 (visual sub-task) and words with three letters (auditory sub-task) for three minutes. The performance was scored based on the correct rate (both sub-tasks), success rate (both sub-tasks), and the number of correct answers in the visual sub-task. Performances of Clinical Assessment for Attention (CAT) developed by The Japan Society for Higher Brain Dysfunction and Kana pick-up test were also measured for TBI patients.

Results: All patients could complete Oiso DT-B without a difficulty. Based on a simple and unique definition of cut-off values, abnormal performance in TBI patients was detected more frequently in the Oiso DT-B than in any sub-task of CAT and Kana pick-up test although the specificity values were comparable.

Conclusion: The Oiso DT-B as well as DT-A also might be valuable and sensitive for detecting inattention including mild deficit.