Ecological validity of neuropsychological and other predictors following head injury

Ecological validity in neurocognitive assessment: Systematized review, content analysis, and proposal of an instrument

OBJECTIVES

The main objectives of this study are to identify the dimensions of Ecological Validity (EV) within the definitions of this concept, understand how they are operationalized in neurocognitive tests, and propose a checklist for EV attributes in neurocognitive tests.

METHOD

A systematized review was combined with content analysis of the selected papers, using the inductive method. We analyzed 82 studies on the EV of neurocognitive tests, 19 literature reviews and 63 empirical studies. Based on this review, we identified the relevant criteria for evaluating EV.

RESULTS

EV is a multidimensional concept with two main dimensions: representativeness and generalization. Representativeness involves the subdimensions simplicity-complexity and artificial-natural and several criteria organized on a continuum from low EV to high EV. Generalization is dependent on representativeness and is influenced by different cognitive and non-cognitive factors. We propose six stages for operationalizing EV, from defining the objectives of the neurocognitive assessment to the methodology for scoring and interpreting the results.

CONCLUSION

This systematized review helps to operationalize the concept of EV by providing a tool for evaluating and improving EV while developing new tests. Further studies with a longitudinal design can compare the predictive value of tests with higher versus lower EV-checklist scores.Key pointsQuestion: Understand the definition of EV, its dimensions and subdimensions, how EV is operationalized in neurocognitive tests and propose a checklist for the EV attributes of neurocognitive tests.Findings: The primary findings were that representativeness and generalization are the main dimensions of EV. Representativeness involves several subdimensions, whereas generalization is dependent on representativeness and is influenced by cognitive and non-cognitive factors. We provided an EV-checklist organized into six parts.Importance: The EV-checklist can be used to guide the development of ecologically valid neurocognitive tests and/or assess the EV of existing ones.Next steps: Examine the predictive value of tests that have higher EV-checklist scores.

Intelligence after traumatic brain injury: meta-analysis of outcomes and prognosis

Worldwide, 54-60 million individuals sustain traumatic brain injury (TBI) each year. This meta-analysis aimed to quantify intelligence impairments after TBI and to determine the value of age and injury severity in the prognosis of TBI. An electronic database search identified 81 relevant peer-reviewed articles encompassing 3890 patients. Full-scale IQ (FSIQ), performance IQ (PIQ) and verbal IQ (VIQ) impairments were quantified (Cohen's d) for patients with mild, moderate and severe TBI in the subacute phase of recovery and the chronic phase. Meta-regressions explored prognostic values of age and injury severity measures for intelligence impairments. The results showed that, in the subacute phase, FSIQ impairments were absent for patients with mild TBI, medium-sized for patients with moderate TBI (d = -0.61, P < 0.001) and large for patients with severe TBI (d = -1.09, P < 0.001). In the chronic phase, FSIQ impairments were small for patients with mild or moderate TBI (d = -0.37 and -0.19, P ≤ 0.008) and large for patients with severe TBI (d = -0.80, P < 0.001). Adults with mild TBI had larger PIQ and VIQ impairments in the chronic phase than children (both Q ≥ 5.21, P ≤ 0.02), whilst children with severe TBI had larger FSIQ and VIQ impairments than adults (both Q ≥ 4.40, P ≤ 0.04). Glasgow Coma Scale score, duration of loss of consciousness and post-traumatic amnesia duration moderately to strongly predicted FSIQ, PIQ and VIQ impairments (0.41 ≤ r ≤ 0.82, P ≤ 0.02), but no differences in predictive value were observed. In conclusion, TBI causes persisting intelligence impairments, where children may have better recovery from mild TBI and poorer recovery from severe TBI than adults. Injury severity measures predict intelligence impairments and do not outperform one another.

A Systematic Review of Early Prognostic Factors for Return to Work After Traumatic Brain Injury

This article presents a systematic review identifying variables and their prognostic value for return to work (RTW) after traumatic brain injury (TBI). RTW has been identified as being a key goal following TBI, with estimates ranging from 10% to 70%. Prediction of postinjury employment is important for planning rehabilitation and structuring individualised vocational services. Studies examining prognostic factors were identified by searching four electronic databases, until June 2006. Searches yielded 1948 studies of which 55 met inclusion criteria and were subsequently rated for methodological quality. Mean methodological score for included studies was 3.9/6 (SD0.9, range 1–6). Analysis focused on a subset of 27 studies which provided sampling from all three domains of preinjury, injury and early postinjury variables. Few studies considered preinjury variables, apart from simple demographics. Only five studies considered preinjury employment, which was a significant predictor in each case. Severity of injury variables were invariably examined, but were significant predictors in only 8/27 studies (30%). For early postinjury variables, 14/27 studies entered cognitive variables with 12/14 (86%) identifying them as significant predictors; 3/27 studies examined neurophysical variables, with 2/3 (67%) studies finding them significant; and 12/27 studies examined multidimensional/participation variables which were statistically significant individual predictors in 8/12 (67%) cases. The results are discussed in the context of methodological issues encountered during the course of the review that require addressing in future studies.

Pre-Injury, Injury and Early Post-Injury Predictors of Long-Term Functional and Psychosocial Recovery After Severe Traumatic Brain Injury

Background: Findings from prognostic studies of functional and psychosocial recovery after traumatic brain injury (TBI) reported to date have been limited by the restricted timeframe for prediction, generally within the first 5 years post-trauma. This investigation examined prediction of functional and psychosocial recovery in the medium-term (6 years post-trauma; Time 1) and long-term (23 years post-trauma; Time 2). Methods: The participants comprised a consecutive series of the first 100 patients with severe TBI receiving their primary rehabilitation at a regionally based unit. At the 23-year follow-up, 91% of the sample was traced: 17 had died, 5 declined participation, and 69 were interviewed, with 68 participating at both Time 1 and Time 2. Five outcome domains were examined: mobility, self-care, employability, relationships and living skills. Results: Very few of seven pre-injury variables were significantly correlated with any of the outcome variables. A series of logistic regression analyses successfully predicted levels of recovery in all domains using four predictor variables: pre-injury occupational status, duration of post-traumatic amnesia, and physical and neuropsychological disability at rehabilitation discharge. At Time 1, 60% or more of the variance was accounted for in four of the five domains, and at Time 2, more than 40% of the variance was accounted for in all domains. Sensitivity ranged from 62% (self-care) to 90% (mobility). With a single exception (employability at Time 2), specificity was also high, ranging from 80% (relationships) to 98% (mobility). Comparable accuracy rates were also found for positive and negative predictive power. Conclusions: These results demonstrate impressive predictive capacity of early post-trauma variables for the very long-term levels of recovery. They provide guidance for the tailoring of individual rehabilitation programs and the identification of people who may require special supports after rehabilitation discharge.

Investigation of factors related to employment outcome following traumatic brain injury: a critical review and conceptual model

PURPOSE

The purpose of this article is to critically review the literature to examine factors that are most consistently related to employment outcome following traumatic brain injury (TBI), with a particular focus on metacognitive skills. It also aims to develop a conceptual model of factors related to employment outcome.

METHOD

The first stage of the review considered 85 studies published between 1980 and December 2003 which investigated factors associated with employment outcome following TBI. English-language studies were identified through searches of Medline and PsycINFO, as well as manual searches of journals and reference lists. The studies were evaluated and rated by two independent raters (Kappa=0.835) according to the quality of their methodology based upon nine criteria. Fifty studies met the criteria for inclusion in the second stage of the review, which examined the relationship between a broad range of variables and employment outcome.

RESULTS

The factors most consistently associated with employment outcome included pre-injury occupational status, functional status at discharge, global cognitive functioning, perceptual ability, executive functioning, involvement in vocational rehabilitation services and emotional status.

CONCLUSIONS

A conceptual model is presented which emphasises the importance of metacognitive, emotional and social environment factors for improving employment outcome.

The experience of appraisal, coping and adaptive psychosocial adjustment following traumatic brain injury: A qualitative investigation

PURPOSE

The experience of appraisal and coping in relation to psychosocial adjustment was explored with individuals who had sustained a traumatic brain injury.

METHODS

Nine participants were interviewed using a semi-structured schedule. Interpretative phenomenological analysis was used to analyse the data and highlighted four over-riding themes.

RESULTS

The emergent themes included: (1) 'waking up': understanding TBI; (2) 'I keep going': coping with TBI; (3) 'I knew I'd get better': beliefs about TBI; and (4) 'the benefits have far outweighed the consequences': searching for positives. These themes highlighted the adaptive and fluid way in which participants coped over time. In addition, the balance between perceptions of luck vs controllability and optimism vs realism were evident for many participants. All but one participant showed adaptive adjustment; therefore the non-adaptive case was used to critique the emergent themes.

CONCLUSIONS

The case of non-adaptive adjustment illustrated less fluidity in terms of the coping strategies utilised, little perceived controllability and a greater degree of externalizing blame. The findings give some direction to neuropsychological rehabilitation with regard to the pliable nature of appraisals and coping and their potential to facilitate adaptive adjustment.

Social behavior following traumatic brain injury and its association with emotion recognition, understanding of intentions, and cognitive flexibility

Although the adverse consequences of changes in social behavior following traumatic brain injury (TBI) are well documented, relatively little is known about possible underlying neuropsychological deficits. Following a model originally developed for social behavior deficits in schizophrenia, we investigated whether impairments in emotion recognition, understanding of other people's intentions ("theory of mind"), and cognitive flexibility soon after first TBI or 1 year later were associated with self and proxy ratings of behavior following TBI. Each of the three functions was assessed with two separate tests, and ratings of behavior were collected on three questionnaires. Patients with TBI (n = 33) were impaired in emotion recognition, "theory of mind," and cognitive flexibility compared with matched orthopedic controls (n = 34). Proxy ratings showed increases in behavioral problems 1 year following injury in the TBI group but not in the control group. However, test performance was not associated with questionnaire data. Severity of the impairments in emotion recognition, understanding intention, and flexibility were unrelated to the severity of behavioral problems following TBI. These findings failed to confirm the used model for social behavior deficits and may cast doubt on the alleged link between deficits in emotion recognition or theory of mind and social functioning.

Ecological Validity of Neuropsychological Assessment and Perceived Employability

Ecological validity studies that have examined the relationship between cognitive abilities and employment in psychiatric and medical populations have found that a wide range of cognitive domains predict employability, although memory and executive skills appear to be the most important. However, no information is available regarding a patient's self-perceived work attributes and objective neuropsychological performance, and whether the same cognitive domains associated with successful employment are also related to a patient's self-perception of work competence. In the present study, 73 medical and psychiatric patients underwent comprehensive neuropsychological assessment. Step-wise multiple regression analyses revealed that the visual-spatial domain was the only significant predictor of self-perceived work attributes and work competence as measured by the Working Inventory (WI) and the Work Adjustment Inventory (WAI), accounting for 7% to 10% of inventory score variability. The results raise the intriguing possibility that targeting of visual spatial skills for remediation and development might play a separate and unique role in the vocational rehabilitation of a lower SES population, specifically, by leading to enhanced self-perception of work competence as these individuals attempt to enter the job market.

Is Learning and Memory Different in a Virtual Environment?

It has been suggested that virtual reality may provide a medium for producing neuropsychological measures with greater ecological validity. The present study examined the usefulness of virtual reality (VR) to assess learning and memory in individuals with traumatic brain injury (TBI). A total of 20 TBI participants were compared with 20 healthy controls on their ability to learn and recall 16 target items presented within a VR-based generic office environment. The results indicated that VR memory testing accurately distinguished the TBI group from controls. Additionally, non-memory-impaired TBI participants acquired targets at the same rate as HC participants. Finally, there was a significant relationship between the VR Office and a standard neuropsychological measure of memory, suggesting the construct validity of the task. These findings suggest that the VR Office provides a viable medium for measuring learning and memory. The present results provide preliminary support for the ecological validity of the VR Office, which ultimately can improve assessment of real-world functioning following TBI.

African American acculturation and neuropsychological test performance following traumatic brain injury

The present study examined the influence of African American acculturation on the performance of neuropsychological tests following traumatic brain injury (TBI). Seventy one participants already enrolled in a larger-scale study assessing the impact of TBI (i.e., the South Eastern Michigan Traumatic Brain Injury Model Systems project) completed a self-report measure of African American acculturation (African American Acculturation Scale-Short Form; Landrine & Klonoff, 1995) in addition to a standardized battery of neuropsychological tests. Hierarchical regression analyses were conducted to evaluate the relationship between level of acculturation and test performance after controlling for injury-related (initial Glasgow Coma Scale score, time since injury) and demographic variables (age, sex, years of education, and socioeconomic status). Lower levels of acculturation were associated with significantly poorer performances on the Galveston Orientation & Amnesia Test, MAE Tokens test, WAIS-R Block Design, Rey Auditory Verbal Learning Test, and Symbol Digit Modalities Test. Decreased levels of acculturation were also significantly related to lower scores on a composite indicator of overall neuropsychological test performance. In addition, the examiner's ethnicity (Black or White) was related with scores on a few of the tests (i.e., Block Design, Trail Making Test), but was not significantly associated with the overall neuropsychological test performance. Overall, these findings suggest that differences in cultural experience may be an important factor in the neuropsychological assessment of African Americans following TBI, and provide additional support for the hypothesis that cultural factors may partially account for the differences among ethnic/cultural groups on neuropsychological tests.

A comparison of the effect of diphenhydramine and desloratadine on vigilance and cognitive function during treatment of ragweed-induced allergic rhinitis

BACKGROUND

Decrements in cognitive performance are associated with the use of sedating antihistamines. Most, but not all, second-generation antihistamines have been found to be nonsedating.

OBJECTIVE

To examine the central nervous system (CNS) profile of a new second-generation antihistamine, desloratadine.

METHODS

Subjects with ragweed-induced allergic rhinitis (aged 18-60 years) who demonstrated a predetermined severity of symptoms after priming with ragweed pollen in the Environmental Exposure Unit were randomized to receive a single dose of desloratadine, 5 mg; diphenhydramine, 50 mg; or placebo. A comprehensive battery of repeatable, automated neuropsychological tests was administered to subjects before treatment (symptomatic baseline) and 90 minutes after taking study medication.

RESULTS

Both desloratadine (P = .04) and diphenhydramine (P < .01) alleviated the symptoms of allergic rhinitis compared with placebo, but treatment with diphenhydramine was associated with clinically meaningful decrements on all vigilance parameters (P < .05 for desloratadine-diphenhydramine contrasts). Also, subjects treated with diphenhydramine performed significantly worse than subjects given desloratadine or placebo across all cognitive domains evaluated. Most effect sizes for the mean desloratadine and diphenhydramine differences were between 0.4 and 0.8 (moderate to high). Stanford Sleepiness Scale scores also indicated significantly more somnolence with diphenhydramine vs desloratadine or placebo (P < .001). There were no significant differences on any of the cognitive parameters between subjects treated with desloratadine and those given placebo.

CONCLUSIONS

Desloratadine improved ragweed-induced allergic rhinitis symptoms without adversely affecting performance. Diphenhydramine improved allergic rhinitis symptoms but caused significant decrements in vigilance and cognitive functioning. Thus, efficacy of antihistamine treatment must be balanced against the associated effects on CNS functioning.

Predictors and Indicators of Return to Work following Traumatic Brain Injury in South Africa: Findings from a Preliminary Experimental Database

Traumatic brain injury (TBI) affects a substantial portion of the South African population every year. However, there is little empirical evidence available regarding eventual outcome after injury in South Africa. In particular, there is little information regarding the ability of head injured individuals to return to their places of employment following injury, or what factors are most closely related to a successful return to work. This study explored the return to work of a specific group of individuals with TBI, in relation to a number of domains, including: rate and nature of return to work, pre-morbid and accident variables that appeared to be related to return to work, and the relationship between return to work and other aspects of outcome, specifically communicative, cognitive, physical and emotional outcome. The study took the form of a detailed record review of a group of subjects seeking medico-legal compensation, using a specially designed data recording form and computerised database. Results indicated a poor rate of return to work in this sample (32%), with significant changes in work status post-injury. The strongest pre-morbid predictors of outcome were found to be first language and pre-injury educational level, with African language speakers and those with an educational level of matriculation or less being at a significant disadvantage. Numerous communicative and cognitive difficulties were significantly related to a failure to RTW, including difficulties in: motor speech, comprehension, expression, attention, speed of processing, incidental visual memory, cognitive flexibility and insight. These results indicate the multi-factorial nature of outcome following head injury in the sample.

Quantitative proton MRS predicts outcome after traumatic brain injury

OBJECTIVE

To determine whether proton MRS (1H-MRS) neurochemical measurements predict neuropsychological outcome of patients with traumatic brain injury (TBI).

BACKGROUND

Although clinical indices and conventional imaging techniques provide critical information for TBI patient triage and acute care, none accurately predicts individual patient outcome.

METHODS

The authors studied 14 patients with TBI soon after injury (45+/-21 days postinjury) and again at 6 months (172+/-43 days) and 14 age-, sex-, and education-matched control subjects. N-acetylaspartate (NAA), creatine, and choline were measured in normal-appearing occipitoparietal white and gray matter using quantitative 1H-MRS. Outcome was assessed with the Glasgow Outcome Scale (GOS) and a battery of neuropsychological tests. A composite measure of neuropsychological function was calculated from individual test z-scores probing the major functional domains commonly impaired after head trauma.

RESULTS

Early NAA concentrations in gray matter predicted overall neuropsychological performance (r = 0.74, p = 0.01) and GOS (F = 11.93, p = 0.007). Other metabolite measures were not related to behavioral function at outcome.

CONCLUSION

1H-MRS provides a rapid, noninvasive tool to assess the extent of diffuse injury after head trauma, a component of injury that may be the most critical factor in evaluating resultant neuropsychological dysfunction. 1H-MRS can be added to conventional MR examinations with minimal additional time, and may prove useful in assessing injury severity, guiding patient care, and predicting patient outcome.