Cognitive functioning after mild traumatic brain injury: Systematic review of neuropsychological test performances across recovery phases and cognitive domains

Objectives: Worldwide, millions of people sustain a mild traumatic brain injury (mTBI) every year. mTBI can negatively affect cognitive functioning, but it is insufficiently clear to what extent this effect varies by phase of recovery and by cognitive domain. The current study concerns a systematic review of neuropsychological test performances after mTBI in a general adult population. With this systematic review, we aim to provide a comprehensive overview of recent literature regarding cognitive functioning after mTBI across the acute (0-3 months), subacute (3-6 months), early chronic (6-12 months) and late chronic (>12 months) phases of recovery.
Methodology: PubMed and PsycINFO were systematically searched using a comprehensive search strategy. Records were screened in a two-step process. Eligibility criteria concerned the definition of mTBI, generalizability of samples, assessment of cognitive functioning with neuropsychological tests or screenings, and comparison to a control group. Methodological quality of studies was assessed using the Newcastle-Ottawa Scale. Data were synthesized by phase of recovery.
Results: Lowered performance by the mTBI groups, as compared to control groups, was found in the acute phase after injury, and to a lesser extent also in the subacute phase. Mental speed, attention and memory were most often affected. In most studies, differences between mTBI and control groups were no longer found in the chronic phases.
Conclusions: This systematic review adds to existing research by stratifying neuropsychological performances post-mTBI by phase of recovery and by cognitive domain. Although mild cognitive impairments may present in the (sub)acute phase, there is limited evidence for long-lasting impairments on the group level. These findings can aid clinicians in evaluating patients’ cognitive functioning after mTBI. When used in conjunction with information about other relevant factors, such as fatigue and mental distress, this allows for personalized clinical management for patients with mTBI.