Speed of processing and strategic control of attention after traumatic brain injury

• Published in: Journal of clinical and experimental neuropsychology Vol. 37; no. 10; pp. 1024 - 1035
• Main Authors: Dymowski, Alicia Rhian, Owens, Jacqueline Anne, Ponsford, Jennie Louise, Willmott, Catherine
• Format: Journal Article
• Language: English
• Published: England Routledge 26-11-2015
• Subjects: Adolescent; Adult; Aged; Attention; Attention Deficit Disorder with Hyperactivity - diagnosis; Attention Deficit Disorder with Hyperactivity - etiology; Brain Injuries - complications; Cognition Disorders - diagnosis; Cognition Disorders - etiology; Female; Glasgow Coma Scale; Humans; Information processing speed; Male; Memory, Short-Term - physiology; Mental Processes - physiology; Middle Aged; Neuropsychological Tests; Psychomotor Performance - physiology; Reading; Statistics, Nonparametric; Strategic control; Trauma Severity Indices; Traumatic brain injury; Working memory; Young Adult; Traumatic brain injury; Information processing speed; Strategic control; Working memory; Attention
• ISSN: 1380-3395; 1744-411X
• DOI: 10.1080/13803395.2015.1074663

Introduction: Slowed information processing speed has consistently been documented after traumatic brain injury (TBI). Debate continues as to whether deficits in strategic control are proportionate to, or remain after controlling for, reduced speed of processing. The study aim was to investigate the association of speed of processing and strategic control of attention with working memory, selective attention, response inhibition, and mental flexibility task performance after TBI using traditional and novel clinical measures. Method: Twenty-five individuals with complicated mild to severe TBI (post-traumatic amnesia duration, M = 39.52 days, SD = 38.34; worst Glasgow Coma Scale score, M = 7.33, SD = 4.35; time post-injury, M = 392.64 days, SD = 537.19) and 25 matched healthy controls completed assessment of attentional and executive functioning. Measures included the Symbol Digit Modalities Test (SDMT), the computerized Selective Attention Task (SAT), the Ruff 2&7 Selective Attention Test (2&7), the visual n-back, Digit Span, Hayling Test, and Trail Making Test (TMT). Results: t tests revealed that individuals with TBI demonstrated reduced processing speed on the SDMT, n-back, SAT, 2&7, Hayling Test, and TMT-A (p ≤ .002 for all). Digit Span performance did not differ between groups. Mixed-model ANOVAs revealed that individuals with TBI demonstrated a disproportionate increase in reaction time with complexity, which was accounted for by speed on the SAT but remained on the Hayling Inhibition Test after controlling for speed in ANCOVAs. Mann-Whitney U tests revealed that individuals with TBI also made more errors on the Hayling Test, missed responses on the n-back and were unable to benefit from the automatic condition of the 2&7. Conclusions: While slowed speed of information processing was pervasive across tasks after TBI, residual difficulties in response inhibition remained after controlling for slowness, which suggests impaired strategic control. These findings support targeted intervention for slowed speed of thinking and inhibition following TBI.