Methodological Issues in Longitudinal Research on Cognitive Recovery after Traumatic Brain Injury: Evidence from a Systematic Review

Neuropsychological recovery during the first 12 months after severe traumatic brain injury: A longitudinal study with monthly assessments

Neuropsychologists are commonly asked practical questions about cognitive recovery in the first year following moderate-to-severe traumatic brain injury (TBI), however guiding evidence to provide answers is limited. The design of this longitudinal study rectifies methodological problems in the literature by taking serial assessments on a monthly basis from 3- to 12-months post-trauma in a severe TBI sample (n = 23), and using four alternate forms of a brief yet sensitive cognitive assessment battery. Fifteen variables sampling seven cognitive domains were used: orientation, attention, processing speed, executive function, memory, language and visuospatial function. A matched control group (n = 23) was used to establish equivalence of the four alternate forms (no statistically significant differences), document practice effects (no statistically significant differences), and provide a comparison standard of cognitive functioning against which to interpret the TBI recovery curves. Twenty-one of 23 consenting TBI participants continued with the serial assessments. Hierarchical growth model analyses typically revealed linear recovery trajectories over the first 12 months. However, by 12-months post-trauma, a significant proportion (up to 36%) had residual mild to severe impairments in various cognitive domains. These results provide detailed information about patterns of cognitive recovery that also have direct clinical application.

Trajectory of 10-Year Neurocognitive Functioning After Moderate-Severe Traumatic Brain Injury: Early Associations and Clinical Application

OBJECTIVE

This study aimed to explore the 10-year trajectories of neurocognitive domains after moderate-severe traumatic brain injury (TBI), to identify factors related to long-term neurocognitive functioning, and to investigate whether performance remained stable or changed over time.

METHOD

Seventy-nine patients with moderate-severe TBI between the ages of 16 and 55 years were assessed at 3 months, 1, 5, and 10 years postinjury using neuropsychological tests and functional outcomes. Three hierarchical linear models were used to investigate the relationships of domain-specific neurocognitive trajectories (Memory, Executive function, and Reasoning) with injury severity, demographics, functional outcome at 3 months (Glasgow Outcome Scale-Extended) and emotional distress at 1 year (Symptom Checklist 90-Revised).

RESULTS

Education, injury severity measures, functional outcome, and emotional distress were significantly associated with both Memory and Executive function. Education and emotional distress were related to Reasoning. The interaction effects between time and these predictors in predicting neurocognitive trajectories were nonsignificant. Among patients with data at 1 and 10 year follow-ups (n = 47), 94-96% exhibited stable scores on Executive function and Reasoning tasks, and 83% demonstrated stable scores on Memory tasks. Significant memory decline was presented in 11% of patients.

CONCLUSIONS

The findings highlight the differential contribution of variables in their relationships with long-term neurocognitive functioning after moderate-severe TBI. Injury severity was important for Memory outcomes, whereas emotional distress influenced all neurocognitive domains. Reasoning (intellectual) abilities were relatively robust after TBI. While the majority of patients appeared to be cognitively stable beyond the first year, a small subset demonstrated a significant memory decline over time.

Relationship of Cerebral Blood Flow to Cognitive Function and Recovery in Early Chronic Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of morbidity worldwide, for which biomarkers are needed to better understand the underlying pathophysiology. Microvascular injury represents a subset of pathological mechanisms contributing to cognitive dysfunction after TBI, which may also impair subsequent neural repair thereby inhibiting cognitive recovery. Magnetic resonance imaging (MRI)-based measurement of cerebral blood flow (CBF) by arterial spin labeling (ASL) provides an appealing means of assessing microvascular disruption in TBI; however, the relationship between CBF alterations in the early chronic post-TBI setting and cognitive dysfunction as well as subsequent cognitive recovery remain poorly understood. Structural MRI and ASL were performed in 42 TBI subjects 3 months post-injury and 35 matched healthy controls. Neuropsychological testing was performed in each subject, as well as in a subset of TBI patients (n = 33) at 6 and/or 12 months post-injury. TBI and control subject CBF data were compared between groups in a voxel-wise fashion while controlling for the effects of structural atrophy. A region-of-interest approach was then used to compare CBF to clinical and neuropsychological measures within the TBI group in a cross-sectional fashion, as well as to the degree of subsequent cognitive recovery among subjects with follow-up testing. At 3 months post-injury, the TBI group demonstrated lower performance in each cognitive domain (p < 0.05), as well as widespread reductions in gray matter CBF independent of structural atrophy (p < 0.05). Within the TBI group, CBF was moderately correlated with injury severity (r = -0.43; p = 0.009) and executive function (r = 0.43; p = 0.01). In the longitudinal analysis, there was a positive correlation between initial CBF and processing speed recovery (r = 0.43; p = 0.015) independent of age, education level, and initial test score. Early chronic TBI is associated with widespread gray matter CBF deficits, which are correlated with injury severity and cognitive dysfunction. CBF may predict subsequent recovery in some cognitive domains.

Patterns of narrative discourse in early recovery following severe Traumatic Brain Injury

Primary Objective: To investigate the nature and patterns of narrative discourse impairment in people with severe Traumatic Brain Injury (TBI) during early recovery.Methods and Procedures: A single image picture description task was administered to 42 participants with severe TBI at 3 and 6-months post-injury. The same task was administered to 37 control participants. Discourse samples were analyzed with measures of productivity, informativeness and story organization. The performance of people with TBI was compared with the control group at both 3 and 6 months, and the performance of the participants with TBI was also compared across the two time points. Individual patterns of performance were also examined.Results: Inferential analyses revealed significant differences between the control group and the group with TBI on informativeness at both time points and  number of complete episodes at 3 months, but no significant differences for productivity measures. There was no significant change for the group with TBI between 3 and 6 months. However, individual improvement over time was observed.Conclusions: People with TBI have discourse difficulties early post TBI that are also present at 6-months post-injury. In order to understand longer-term discourse recovery, it is necessary to examine participant patterns over further time points on this narrative task.

Cognitive functioning following traumatic brain injury: The first 5 years

OBJECTIVE

This study reports the results from a 5-year longitudinal investigation of the prevalence and severity of cognitive deficits following significant (i.e., ventilation required for > 24 hours) traumatic brain injury. The changes in performance, either improvement or decline, across five domains of cognitive functioning are described.

METHOD

A group of 56 adults was assessed at approximately 6 months, 1 year, and 5 years following injury.

RESULTS

Impairment was evident on all measures but prevalence and rate of improvement varied. Overall, by 5 years post-injury over 85% of patients were not impaired on measures of general intelligence, simple attention, and visual perception. However, 28% of patients continued to show some degree of impairment on complex attention and verbal fluency, and performance on verbal memory remained impaired for 60% of patients. There was also evidence for deterioration in complex attention and verbal memory between 1 year and 5 years. ANOVAs showed that improvement occurred on most measures between 6 months and 1 year, but there was both improvement and decline on some measures between 1 year and 5 years.

CONCLUSIONS

The findings show that there is considerable heterogeneity in cognitive outcome following TBI, with some deterioration evident over the long term.

Measuring reliable change in traumatic brain injury (TBI): The pitfalls of using readily available formulae

Individuals with a traumatic brain injury (TBI) frequently undergo repeat neuropsychological assessments. Reliable change (RC) methodologies based on general population normative data are often used to assess for clinically significant change. The consequence of applying such methodologies to an individual with a TBI needs investigation. The current study tested the validity of readily available formulae in moderate to severe TBI participants who were >2 years postinjury. Participants were administered the Wechsler Adult Intelligence Scale-IV/Wechsler Memory Scale-IV (WAIS/WMS-IV) battery on two occasions across an approximate 1 year interval. Index scores were entered into 10 RC formulae to assess their validity in individuals with a TBI. Findings revealed that the formulae used in the study are relatively interchangeable in regards to WAIS-IV assessment, but that many of the formulae identified statistically unexpected rates of RC change in memory tasks assessed by the WMS-IV. Two formulae that did not contain statistical manipulations for practice effects performed relatively well in regards to memory assessment. Therefore, indiscriminate use of RC formulae could lead to over identifying memory decline in the TBI populations. The results suggest that either Iverson or Jacobson and Truax formulae can be used to assess RC for memory in moderate to severe TBI populations.

Neuropsychological Recovery Trajectories in Moderate to Severe Traumatic Brain Injury: Influence of Patient Characteristics and Diffuse Axonal Injury

OBJECTIVES

The goal of the present study was to elucidate the influence of demographic and neuropathological moderators on the longitudinal trajectory neuropsychological functions during the first year after moderate to severe traumatic brain injury (TBI). In addition to examining demographic moderators such as age and education, we included a measure of whole-brain diffuse axonal injury (DAI), and examined measures of processing speed (PS), executive function (EF), and verbal learning (VL) separately.

METHODS

Forty-six adults with moderate to severe TBI were examined at 3, 6, and 12 months post-injury. Participants underwent neuropsychological evaluation and neuroimaging including diffusion tensor imaging. Using linear mixed effects modeling, we examined longitudinal trajectories and moderating factors of cognitive outcomes separately for three domains: PS, VL, and EF.

RESULTS

VL and EF showed linear improvements, whereas PS exhibited a curvilinear trend characterized by initial improvements that plateaued or declined, depending on age. Age moderated the recovery trajectories of EF and PS. Education and DAI did not influence trajectory but were related to initial level of functioning for PS and EF in the case of DAI, and all three cognitive domains in the case of education.

CONCLUSIONS

We found disparate recovery trajectories across cognitive domains. Younger age was associated with more favorable recovery of EF and PS. These findings have both clinical and theoretical implications. Future research with a larger sample followed over a longer time period is needed to further elucidate the factors that may influence cognitive change over the acute to chronic period after TBI. (JINS, 2018, 24, 237-246).

Flow and Meaningfulness as Mechanisms of Change in Self-Concept and Well-Being Following a Songwriting Intervention for People in the Early Phase of Neurorehabilitation

Anecdotal evidence suggests that songwriting assists people with spinal cord injury (SCI) or acquired brain injury (ABI) to explore threats to self-concept, yet studies that explore the mechanisms of change have not been reported. In a pilot study, we explored the correlations between changes in self-concept and well-being, with mechanisms of flow and meaningfulness of songwriting. Five people with ABI (all male) and 5 SCI (4 males, 1 female) (mean age 38.90 years, SD = 13.21), with an average 3 months post-injury, participated in a 12-session songwriting program that targeted examination of self-concept. Measures of self-concept, depression, anxiety, emotion regulation, affect, satisfaction with life, and flourishing were collected pre-, mid-, and post-intervention, and compared with repeated measures of flow and meaningfulness of songwriting. Medium effects were found for changes in self-concept (d = 0.557) and depression (d = 0.682) and approached a medium effect for negative affect (d = 0.491). Improvements in self-concept over time were associated with decreases in depression (r p = -0.874, n = 9, p < 0.01), anxiety (r p = -0.866, n = 9, p < 0.01), and negative affect (r p = -0.694, n = 10, p < 0.05), and an increase in flourishing (r p = +0.866, n = 9, p < 0.01) and positive affect (r p = + 0.731, n = 10, p < 0.05). Strong experiences of flow were not positively correlated with positive changes to self-concept and well-being, whereas deriving high levels of meaning were associated with increased negative affect (r p = +0.68 p < 0.05), increased anxiety (r p = +0.74, p < 0.05), and reduced emotional suppression (r p = -0.58, p < 0.05). These findings show that the targeted songwriting intervention appears to be positively associated with enhanced well-being outcomes. However, the findings also suggest that people who find the songwriting process has strong meaning for them might be more likely to start accepting their emotions and as a result experience an increase in anxiety and depression, although full, mediated regression analyses with larger sample sizes are required to explore this further. Acknowledging their changed circumstances may nonetheless assist people with SCI and ABI to grieve their losses and facilitate the building of a healthy post-injured self-concept. We propose that there may be other mechanisms more critical in facilitating the positive changes in self-concept and well-being than flow and meaning, such as the role of story-telling and the impact of music in facilitating the consolidation of self-concept explorations in memory.