Cognitive Outcomes Among Adults Following Traumatic Brain Injury: A Systematic Review Using the Progress-plus Framework

Objective(s): To examine cognitive recovery following moderate-to-severe traumatic brain injury (MS-TBI) in adults and to describe the integration of social equity parameters in research utilizing the PROGRESS-Plus framework.

Data Sources: We searched Embase, Medline, Scopus, Cochrane Central Register for Controlled Trials, and PsycINFO from inception until December 2016, with an update on April 8, 2024.

Study Selection: We included peer-reviewed longitudinal studies published in English, focusing on cognitive outcomes in adults (≥ 18 years) with MS-TBI using standardized measures. We identified 17 studies in the initial search and 11 additional articles from the updated search, out of 29,566 and 21,167 retrieved, respectively. Data analysis included 28 studies.

Data Extraction: We extracted data concerning study design, participant and TBI characteristics, and cognitive outcome measures along with social equity parameters using a customized form from the previously published review. The first author conducted the extraction and senior author reviewed the data for accuracy. Two authors independently conducted a critical appraisal using Hayden’s criteria for prognostic research, resolving any conflicts with the senior author.

Data Synthesis: Twenty-eight selected studies included 2,407 participants (mean age 32.8 years, mean 75.5% male). The baseline assessment ranged from 20 days to 10 years and follow-up assessments varied from one month to 20 years post-TBI. Most studies (78%) reported improved cognitive functions from baseline to the last follow-up. A few studies (ranging between 2 and 6 studies) met the criteria for meta-analysis. We found a trend of improvement on the Trail Making Test Part B, Controlled Oral Word Test, Digit Span Backward, and Rey Auditory Verbal Learning Test, although results were not statistically significant. For the FIM-cognitive domain, results were statistically significant (pooled mean difference 4.05, 95% confidence interval: 1.52, 6.57). Half of the studies considered at least one PROGRESS-Plus parameters in their analysis, most frequently age, gender/sex, and education. We observed a trend of a higher proportion of cognitive improvement in studies that did not account for any of these parameters compared to those that considered at least one.

Conclusions: The course of cognitive trajectories after MS-TBI was not uniform. The limited consideration of social equity parameters in the published literature may have contributed to this variability, indicating a critical research gap. This highlights the direction for future research to better understand cognitive recovery following MS-TBI.

Author(s) Disclosures: No conflicts of interest.

Funding: Canadian Institute of Health Research (Op. Grant: Brain Health and Reduction of Risk for Age-related Cognitive Impairment - KS and Mobilization Grants - Sex and Gender Differences SGD grant # 202306BK5-510306-BKS-ADHD-220229.