Neuropsychological outcome and its correlates in the first year after adult mild traumatic brain injury: A population-based New Zealand study

Abstract

Objective: The relationship between moderate/severe traumatic brain injury (TBI) and cognitive deficits is well known. The nature, duration and predictors of cognitive difficulties post-mild TBI remain unclear. This study examined cognitive, mood and post-concussion outcomes of mild TBI over 1-year post-injury.

Method: Adults (>15 years) with mild TBI (n = 260) completed neuropsychological (CNS-Vital Signs, Behavioural Dyscontrol Scale), mood (Hospital Anxiety Depression Scale) and behavioural assessments (Cognitive Failures Questionnaire, Rivermead Post-Concussion Questionnaire) at baseline, 1-, 6- and 12-months post-injury.

Results: Over the 12-months post-injury self-reported cognition (p = 0.027), post-concussion symptoms (p < 0.001), depression (p < 0.001), anxiety (p < 0.001) and dyscontrol (p = 0.025) improved significantly. Assessments of memory, processing speed, executive function, psychomotor speed/reaction time, complex attention and flexibility also improved significantly. At baseline >20% of individuals produced very low scores on executive ability, complex attention and cognitive flexibility. At 1- and 6-month follow-ups >20% of participants were very low for complex attention, with 16.3% remaining so at 12-months. Executive abilities and speed were related to post-concussion symptoms, mood and self-reported cognition at 12-months.

Conclusions: Whilst significant improvements were noted across measures over time, a significant proportion of individuals still perform poorly on neuropsychological measures 12-months after mild TBI; and these were linked to post-concussion symptoms, mood and self-reported cognitive outcomes. This implies a longer trajectory for recovery than has previously been suggested, which has implications for provision of assessment and rehabilitation services for more extended periods.

• Cognition
• concussion
• mild traumatic brain injury
• mood
• post-concussion

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This study was funded by the New Zealand Health Research Council.