title: Divided attention and mental effort after severe traumatic brain injury.
abstract: The aim of this study was to assess dual-task performance in TBI patients, under different experimental conditions, with or without explicit emphasis on one of two tasks. Results were compared with measurement of the subjective mental effort required to perform each task. Forty-three severe TBI patients at the subacute or chronic phase performed two tasks under single- and dual-task conditions: (a) random generation; (b) visual go-no go reaction time task. Three dual-task conditions were given, requiring either to consider both tasks as equally important or to focus preferentially on one of them. Patients were compared to matched controls. Subjective mental effort was rated on a visual analogic scale. TBI patients showed a disproportionate increase in reaction time in the go-no go task under the dual-task condition. However, they were just as able as controls to adapt performance to the specific instructions about the task to be emphasised. Patients reported significantly higher subjective mental effort, but the variation of mental effort according to task condition was similar to that of controls. These results suggest that the divided attention deficit of TBI patients is related to a reduction in available processing resources rather than an impairment of strategic processes responsible for attentional allocation and switching. The higher level of subjective mental effort may explain why TBI patients frequently complain of mental fatigue, although this subjective complaint seems to be relatively independent of cognitive impairment.
authors.affiliation: Service de Rééducation Neurologique, Formation de Recherche Claude Bernard, Faculté de Médecine Paris-Ile de France Ouest, Université de Versailles-Saint Quentin, Hôpital Raymond Poincaré, Garches 92380, France. philippe.azouvi@rpc.ap-hop-paris.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Azouvi
authors.forename: Josette
authors.initials: J
authors.lastname: Couillet
authors.forename: Michel
authors.initials: M
authors.lastname: Leclercq
authors.forename: Yves
authors.initials: Y
authors.lastname: Martin
authors.forename: Sybille
authors.initials: S
authors.lastname: Asloun
authors.forename: Marc
authors.initials: M
authors.lastname: Rousseaux
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology; D002755:Choice Behavior / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D004193:Discrimination Learning / Q000502:physiology; D005260:Female; D016489:Head Injuries, Closed / Q000150:complications / Q000503:physiopathology; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D005222:Mental Fatigue / Q000175:diagnosis / Q000209:etiology*; D010470:Perceptual Masking; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D012720:Severity of Illness Index