Behavioral Dyscontrol Scale deficits among traumatic brain injury patients, part I: Validation with nongeriatric patients

The Behavioral Dyscontrol Scale is a measure of executive abilities initially designed to predict functional independence in geriatric populations. The current study examined the utility of two Behavioral Dyscontrol Scale (BDS) scoring systems in a nongeriatric sample. The BDS was administered to 49 TBI patients undergoing inpatient and outpatient rehabilitation. The results demonstrate slightly greater utility of the BDS-II scoring system, and support clinical utility of the instrument with nongeriatric patients. Specifically, the Motor Programming Factor and Environmental Independence Factor were more impaired among patients with severe, as compared to mild to moderate, TBIs. In contrast, the Fluid Intelligence Factor was more impaired among patients with frontal, as compared to nonfrontal, injuries. However, when patients were categorized by severity, lesion location differences on the BDS total score and factors were found only for patients with mild to moderate injuries. Similarly, when patients were categorized by lesion location, severity effects were only present among the nonfrontal group. Receiver Operating Characteristic curves demonstrated sensitivity and specificity rates that ranged from 60% to 100% for clinically meaningful cutting scores.     

Executive functions and speed of mental processing in elderly patients with frontal or nonfrontal ischemic stroke

Impairments in executive functions have been related to aging and frontal lobe lesions. Aging also causes slowing of mental processing. We examined whether ischemic stroke in the frontal brain area results in dysexecutive syndrome, or whether the frontal stroke causes increased slowing of mental processing. Neurological, radiological and neuropsychological examinations were carried out 3 months post-stroke on 250 ischemic stroke patients (55-85 years) and on 39 healthy control subjects. Of the patients, 62 had frontal and 188 had nonfrontal lesions. The neuropsychological examination comprised several cognitive domains, including tests considered to measure executive functions. The frontal group was slower than the nonfrontal group in tasks measuring speed of mental processing which were time-limited (Trail Making A, Stroop dots and fluency). They were also inferior in the Digit Span backwards task. There were no differences between the groups in other cognitive domains, nor in some tests which are considered to be measures of executive functions (e.g. WCST). Impairments in executive functions were evident in both the frontal and the nonfrontal groups compared with the controls, but no dysexecutive syndrome specifically related to frontal lesions was found. Frontal stroke related mainly to the slowing of mental processing.     

Factor Structure and Construct Validity of the Behavioral Dyscontrol Scale-II

The Behavioral Dyscontrol Scale-II (BDS-II) was developed as an improved scoring method to the original BDS, which was designed to evaluate the capacity for independent regulation of behavior and attention. The purpose of this study was to evaluate the factor structure and construct validity of the BDS-II, which had not been adequately re-examined since the development of the new scoring system. In a sample of 164 Veterans with a mean age of 35 years, exploratory factor analysis was used to evaluate BDS-II latent factor structure. Correlations and regressions were used to explore validity against 22 psychometrically sound neurocognitive measures across seven neurocognitive domains of sensation, motor output, processing speed, attention, visual-spatial reasoning, memory, and executive functions. Factor analysis found a two-factor solution for this sample which explained 41% of the variance in the model. Validity analyses found significant correlations among the BDS-II scores and all other cognitive domains except sensation and language (which was not evaluated). Hierarchical regressions revealed that PASAT performance was strongly associated with all three BDS-II scores; dominant hand Finger Tapping Test was also associated with the Total score and Factor 1, and CPT-II Commissions was also associated with Factor 2. These results suggest the BDS-II is both a general test of cerebral functioning, and a more specific test of working memory, motor output, and impulsivity. The BDS-II may therefore show utility with younger populations for measuring frontal lobe abilities and might be very sensitive to neurological injury.     

Wisconsin Card Sorting Test performance in patients with focal frontal and posterior brain damage: effects of lesion location and test structure on separable cognitive processes

Forty-six patients with single focal lesions (35 frontal, 11 nonfrontal) were administered the Wisconsin Card Sorting Test (WCST) under three conditions of test administration. The three conditions varied in the amount of external support provided via specificity of instructions. The WCST, while a multifactorial test, is specifically sensitive to the effects of frontal lobe damage if deficits in language comprehension and visual-spatial search are controlled. There is also specificity of functioning within the frontal lobes: patients with inferior medial frontal lesions, unilateral or bilateral, were not impaired on the standard measures although they had increased loss of set when informed of the sorting categories. Verbal instructions may provide a probe to improve diagnosis and prognosis, assessment of the potential efficacy of treatment, and the time frame of plasticity of specific cognitive operations.     

Strategic white matter injury associated with long‐term information processing speed deficits in mild traumatic brain injury

Deficits in information processing speed (IPS) are among the earliest and most prominent cognitive manifestations in mild traumatic brain injury (mTBI). We investigated the impact of white matter fiber location on IPS outcome in an individual basis assessment. A total of 112 acute mild TBI with all CT negative underwent brain DTI and blood sampling for inflammation cytokines within 7 days postinjury and 72 age‐ and sex matched healthy controls with same assessments were enrolled. IPS outcome was assessed by the trail making test at 6–12 month postinjury in mild TBI. Fractional anisotropy (FA) features were extracted using a novel lesion‐load analytical strategy to capture spatially heterogeneous white matter injuries and minimize implicit assumptions of uniform injury across diverse clinical presentations. Acute mild TBI exhibited a general pattern of increased and decreased FA in specific white matter tracts. The power of acute FA measures to identify patients developing IPS deficits with 92% accuracy and further improved to 96% accuracy by adding inflammation cytokines. The classifiers predicted individual's IPS and working memory ratings (r = .74 and .80, respectively, p < .001). The thalamo‐cortical circuits and commissural tracts projecting or connecting frontal regions became important predictors. This prognostic model was also verified by an independent replicate sample. Our findings highlighted damage to frontal interhemispheric and thalamic projection fiber tracts harboring frontal‐subcortical neuronal circuits as a predictor for processing speed performance in mild TBI.     

Factor Analysis of Computerized and Traditional Tests Used in Mild Brain Injury Research

The present study examines the relation between a set of computerized neuropsychological measures, Automated Neuropsychological Assessment Metrics (ANAM), and a set of traditional clinical neuropsychological tests. Both sets of tests have been employed in recent studies of mild brain injury. Factor analysis and stepwise regression indicate that both sets of tests measure similar underlying constructs of cognitive processing speed, resistance to interference, and working memory. The present findings indicate strong concordance between computerized and traditional neuropsychological measures and support the construct validity of ANAM and similar procedures.     

Factor analysis of computerized and traditional tests used in mild brain injury research

The present study examines the relation between a set of computerized neuropsychological measures, Automated Neuropsychological Assessment Metrics (ANAM), and a set of traditional clinical neuropsychological tests. Both sets of tests have been employed in recent studies of mild brain injury. Factor analysis and stepwise regression indicate that both sets of tests measure similar underlying constructs of cognitive processing speed, resistance to interference, and working memory. The present findings indicate strong concordance between computerized and traditional neuropsychological measures and support the construct validity of ANAM and similar procedures.     

Mild head injury and speed of information processing: A prospective study of professional rugby league players

Abstract

The sensitivity of several short tests of speed of information processing to the effects of mild head injury in rugby league football was investigated. The measures used were the Symbol Digit Modalities Test, the Digit Symbol Substitution Test, and the Speed of Comprehension Test. Two studies were conducted, the first to examine the effect of practice, the second to determine sensitivity to cognitive impairment immediately following injury. The first study established alternate form equivalence and demonstrated that performance on the Speed of Comprehension and Digit Symbol Substitution tests improved with practice, whereas the Symbol Digit Modalities test remained stable. A second study of 10 players who subsequently sustained mild head injuries showed that measures of speed of information processing were sensitive to impairment in the postacute phase, whereas an untimed task of word recognition (Spot-the-Word) was not. Speed of Comprehension was more sensitive to postinjury impairment than either the Digit Symbol Substitution or Symbol Digit Modalities tests. A repeated baseline assessment before injury using the higher score to reflect a player's potential, allowed measurement of impaired performance on sensitive tests.     

Diagnostic Utility of Attention Measures in Postconcussion Syndrome

Neuropsychological evaluation may be of particular relevance in the detection of subtle cognitive impairments after mild traumatic brain injury (MTBI), including the subgroup of MTBI patients with a persistent postconcussion syndrome (PCS). Attention measures may be the most sensitive indicators of dysfunction associated with MTBI; however, previous studies have typically relied on the analysis of overall group differences, which may not reflect the diagnostic accuracy of attention measures when applied to individuals with MTBI. In the present study, subjects with persistent symptoms at least 3 months following a mild traumatic brain injury were compared with a sample of community living, normal control subjects in order to evaluate the sensitivity, specificity, and diagnostic accuracy of attention measures. Patients with PCS, screened with conservative inclusion and exclusion criteria, and a matched normal control group were administered six clinical tests of attention: Digit Span, Trail Making Test, Part A and Part B, Stroop Color-Word Test, Continuous Performance Test of Attention (CPTA), Paced Auditory Serial Addition Test (PASAT), and Ruff 2 & 7 Selective Attention Test. Consistent with prior research, these measures exhibited a wide range of sensitivity and specificity to possible cognitive impairment among patients. Attention measures may be the most sensitive indicators of dysfunction associated with PCS. Measures with high specificity (e.g., Stroop Color, and 2 & 7 Processing Speed) were shown to have strong positive predictive value, while measures with high sensitivity (e.g., CPTA) demonstrated strong negative predictive value for diagnosing PCS. Examination of the Odds Ratios indicated that measures assessing processing speed had a reliable, positive association with PCS, while measures without a processing speed component did not. Implications for making informed clinical decisions are discussed.     

Diagnostic utility of attention measures in postconcussion syndrome

Neuropsychological evaluation may be of particular relevance in the detection of subtle cognitive impairments after mild traumatic brain injury (MTBI), including the subgroup of MTBI patients with a persistent postconcussion syndrome (PCS). Attention measures may be the most sensitive indicators of dysfunction associated with MTBI; however, previous studies have typically relied on the analysis of overall group differences, which may not reflect the diagnostic accuracy of attention measures when applied to individuals with MTBI. In the present study, subjects with persistent symptoms at least 3 months following a mild traumatic brain injury were compared with a sample of community living, normal control subjects in order to evaluate the sensitivity, specificity, and diagnostic accuracy of attention measures. Patients with PCS, screened with conservative inclusion and exclusion criteria, and a matched normal control group were administered six clinical tests of attention: Digit Span, Trail Making Test, Part A and Part B, Stroop Color-Word Test, Continuous Performance Test of Attention (CPTA), Paced Auditory Serial Addition Test (PASAT), and Ruff 2 & 7 Selective Attention Test. Consistent with prior research, these measures exhibited a wide range of sensitivity and specificity to possible cognitive impairment among patients. Attention measures may be the most sensitive indicators of dysfunction associated with PCS. Measures with high specificity (e.g., Stroop Color, and 2 & 7 Processing Speed) were shown to have strong positive predictive value, while measures with high sensitivity (e.g., CPTA) demonstrated strong negative predictive value for diagnosing PCS. Examination of the Odds Ratios indicated that measures assessing processing speed had a reliable, positive association with PCS, while measures without a processing speed component did not. Implications for making informed clinical decisions are discussed.     

Frontal lobe damage and tests of executive processing: a meta-analysis of the category test, stroop test, and trail-making test

The Category Test, Trails B, and the interference task of the Stroop Test are among the most commonly administered measures of frontal lobe functioning and are thought to tap different cognitive functions mediated by these brain regions. Two meta-analyses were conducted on these tests to determine their sensitivity to frontal and lateralized frontal brain damage. Study 1 compared participants with frontal lobe damage to those with damage to posterior brain regions, whereas Study 2 compared participants with left and right frontal lobe damage. For each study, effect sizes based on performance differences between the above groups were calculated for the Category Test, Trail-Making Test Parts A and B, and the Stroop Test, including Word, Color, and Color-Word subtests. In Study 1 significant differences between groups were found for Trails A and all Stroop tasks, but in Study 2 the only difference between left and right frontal participants was on the Stroop Color-Word task. Potential reasons why Trails A and the Stroop Test are sensitive to frontal lobe damage are discussed, such as novelty and processing speed, as are clinical implications of these findings. The challenges of research on assessment of frontal lobe functioning are discussed and new developments in this area are highlighted.     

Changes over time in memory, processing speed and clock drawing tests help to discriminate between vascular cognitive impairment, mild cognitive impairment and Alzheimer's disease

Measures of cognitive change over time may help to better discriminate between mild cognitive impairment, Alzheimer's disease and vascular cognitive impairment than single assessments. Our hypothesis was that performance in processing speed and executive function would decline with mild cognitive impairment and Alzheimer's disease. Subjects included 36 controls, 18 cases with mild cognitive impairment, eight with vascular cognitive impairment and 24 with Alzheimer's disease who were tested on a cognitive battery at two episodes with a 12-month interval. Changes in performance were determined for each group with paired means tests. Controls improved in pattern comparison speed and the CLOX, a clock-drawing task to detect dysexecutive function. Those with vascular cognitive impairment declined in letter comparison speed, but improved in paragraph recall. Alzheimer's disease patients declined in CLOX and the Hopkins Verbal Learning Test. The mild cognitive impairment group showed no significant changes. Alzheimer's disease patients on treatment declined in Hopkins Verbal Learning Test, while those without treatment declined in The Placing Test and CLOX. Processing speed decline may be a marker of cerebrovascular disease, while decline in memory and executive function was more evident with Alzheimer's disease.     

Executive dysfunction and periventricular diffusion tensor changes in amnesic mild cognitive impairment and early Alzheimer's disease

Our aim in this study was to explore the neural substrates of executive function in frontal and nonfrontal white matter using diffusion tensor imaging (DTI). We studied the relationship between executive dysfunction and DTI measurements on 13 subjects with amnesic mild cognitive impairment (aMCI), 11 subjects with early Alzheimer's disease (AD), and 16 control subjects. All participants underwent an examination of their intelligence, memory, and executive function and were subjected to DTI. Both aMCI and early AD subjects showed executive function impairment with differential performance in frontal‐related behaviors. Both aMCI and early AD subjects showed increased mean diffusivity in the genu of the corpus callosum and left frontal periventricular white matter (PVWM), whereas subjects with early AD showed an additional decrease in the fractional anisotropy of bilateral frontal PVWM and in the genu of the corpus callosum. The frontal PVWM was associated with performance on the Verbal Fluency Test, the Wisconsin Card Sorting Test (WCST), and Part B of the Trail Making Test. The parietal PVWM was associated with perseverative errors on the WCST and Part A of the Trail Making Test. In summary, executive function was impaired in subjects with aMCI and early AD and was associated with frontal and parietal PVWM changes. These changes may be due to early AD degeneration of the lateral cholinergic projections or to early change of the superior longitudinal fasciculus. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Cognitive impairment in relapsing and primary progressive multiple sclerosis: mostly a matter of speed.

Based on the assumption that cognitive impairment in MS is consistent with subcortical dementia, a battery of neuropsychological tests was assembled that included measures of executive function (Tower of London and Wisconsin Card Sorting Test), verbal learning and memory (a paired associates learning test), and speeded information processing (Stroop Color Word Interference Test). The battery was administered to patients with relapsing and primary progressive MS and to healthy controls. Differences between patients and controls occurred on several of the measures. However, when differences with respect to fatigue and depression were statistically controlled, the only differences that remained significant involved measures relating to the speed of information processing. Patients performed more slowly than controls, with the disparity being greater for relapsing patients than for those with primary progressive disease. The slowing was evident on measures of automatic as well as controlled processing and regardless of whether speed was an explicit feature of successful performance or recorded unobstrusively while the patient concentrated on planning a correct solution to a problem. Parallels were noted between cognitive slowing associated with MS and that of normal aging.     

A longitudinal study of the evolution of cognitive function and affective state in patients with amyotrophic lateral sclerosis.

OBJECTIVES: The study aimed to evaluate cognitive function and emotional reactivity in 18 patients with ALS, compared to 19 matched controls, and assess their evolution over a 12-month period. METHODS: 18 ALS patients and 19 matched controls were included, and assessed at inclusion, six months and twelve months later. Depression was evaluated with the Geriatric Depression Scale, and cognitive function with the Folstein Mini Mental State. A battery of psychometric tests (Wisconsin Card Sorting Test (WCST), the numerical Empan test, the Trail-making test, the Boston Naming Test, the 15-word Rey memory test, the Benton visual retention test and the Raven Progressive Matrix) was used to measure frontal processing and non-frontal function. Emotional reactivity was measured with the film-evoked emotions test. RESULTS: ALS patients were significantly more depressed than controls, as measured on the Geriatric Depression Scale, and depression increased over the study period. There was a very mild defect in cognitive function, and a performance deficit in the Trail-making test, a measure of frontal processing. These deficits, unlike neuromuscular function and depression, did not aggravate over the 12 months of the study. There was no observable change in non-frontal function. Emotional reactivity did not differ significantly between ALS patients and controls. CONCLUSIONS: This study provides further evidence for a mild defect in frontal cognitive processing in ALS patients that evolves only slowly, if at all, with time.     

Inhibition of ongoing responses in patients with traumatic brain injury

In addition to slowness of information processing, it is often assumed that executive functions are deficient in patients with traumatic brain injuries (TBI). The aim of this study was to investigate a specific executive function, the inhibition of ongoing responses in TBI. Twenty-seven patients with TBI and 27 orthopedic patients (OC) performed the stop signal task, which allows the estimation of the time it takes to inhibit an ongoing response. Contrary to expectations, patients with TBI did not perform worse than the OC in the inhibition of ongoing responses. Furthermore, subgroups of the TBI, with frontal and nonfrontal lesions, and with focal versus diffuse damage, did not show any differences in performance. None of the clinical, demographic or neuropsychological data had a significant relationship to inhibition time, apart from age, which showed a significant relationship only in the TBI. It seems likely that deficits in the inhibition of ongoing responses are not very common after TBI.     

California Verbal Learning Test indicators of suboptimal performance in a sample of head-injury litigants

Cutoff scores suggested by Millis, Putnam, Adams, and Ricker (1995) for detecting suboptimal performance on indices from the California Verbal Learning Test (CVLT) were evaluated using data from 193 compensation-seeking participants. All participants claimed to have suffered a blow to the head in an accident causing subsequent deterioration in cognitive function. The participants were divided into those with negligible or possible mild brain injuries and those with clear evidence of moderate to severe brain injuries. In addition to the CVLT, all participants were administered the Computerized Assessment of Response Bias (CARB), a two-alternative forced choice test of recognition memory that is used to detect feigned cognitive impairment. For all CVLT indices, the distributions of outcome (valid vs. suboptimal performance) was unrelated to age and brain injury severity, and only weakly associated with education. However, a significantly higher proportion of males than females obtained scores in the suboptimal performance range. The CVLT indices were not fully redundant with each other with respect to binary participant classifications; substantial disagreement between pairwise classifications was found among those participants who obtained at least one score in the suboptimal performance range. CVLT index classifications were also found to be non-redundant with classifications based on CARB scores. The CVLT may thus add useful data over and above that obtained from symptom validity testing. However, the data suggest that the use of the strategy where any one or more below-cutoff CVLT scores are considered a positive indicator of suboptimal performance may be associated with a higher than acceptable false-positive error rate.     

California Verbal Learning Test Indicators of Suboptimal Performance in a Sample of Head-Injury Litigants

Cutoff scores suggested by Millis, Putnam, Adams, and Ricker (1995) for detecting suboptimal performance on indices from the California Verbal Learning Test (CVLT) were evaluated using data from 193 compensation-seeking participants. All participants claimed to have suffered a blow to the head in an accident causing subsequent deterioration in cognitive function. The participants were divided into those with negligible or possible mild brain injuries and those with clear evidence of moderate to severe brain injuries. In addition to the CVLT, all participants were administered the Computerized Assessment of Response Bias (CARB), a two-alternative forced choice test of recognition memory that is used to detect feigned cognitive impairment. For all CVLT indices, the distributions of outcome (valid vs. suboptimal performance) was unrelated to age and brain injury severity, and only weakly associated with education. However, a significantly higher proportion of males than females obtained scores in the suboptimal performance range. The CVLT indices were not fully redundant with each other with respect to binary participant classifications; substantial disagreement between pairwise classifications was found among those participants who obtained at least one score in the suboptimal performance range. CVLT index classifications were also found to be non-redundant with classifications based on CARB scores. The CVLT may thus add useful data over and above that obtained from symptom validity testing. However, the data suggest that the use of the strategy where any one or more below-cutoff CVLT scores are considered a positive indicator of suboptimal performance may be associated with a higher than acceptable false-positive error rate.     

Practical methods for the clinical assessment of information processing speed

The rate at which individuals are capable of processing information is considered a sensitive indicator of brain dysfunction, particularly among clinical populations whose neurocognitive impairments generally are considered relatively mild in nature. Assessment of information processing speed often is confounded, however, by comorbid impairments in other constructs of neurocognition, including attentional capacity, visuospatial perception, language, immediate memory, and motor speed/coordination. This investigation examined the effect of controlling for various potential confounders on the strength of associations among several potential measures of information processing speed. Participants were 64 patients diagnosed with clinically definite multiple sclerosis. Analysis indicated consistent significant and positive associations among measures of processing speed, which generally persisted despite simultaneous statistical control of potential confounding factors. Results imply that examined confounding variables are similarly related to the measures of processing speed. Therefore, any of the measures of information processing speed considered in this study may be used as a proxy for the more direct measure of this construct derived from the Sternberg Memory Scanning Test.     

PRACTICAL METHODS FOR THE CLINICAL ASSESSMENT OF INFORMATION PROCESSING SPEED

The rate at which individuals are capable of processing information is considered a sensitive indicator of brain dysfunction, particularly among clinical populations whose neurocognitive impairments generally are considered relatively mild in nature. Assessment of information processing speed often is confounded, however, by comorbid impairments in other constructs of neurocognition, including attentional capacity, visuospatial perception, language, immediate memory, and motor speed/coordination. This investigation examined the effect of controlling for various potential confounders on the strength of associations among several potential measures of information processing speed. Participants were 64 patients diagnosed with clinically definite multiple sclerosis. Analysis indicated consistent significant and positive associations among measures of processing speed, which generally persisted despite simultaneous statistical control of potential confounding factors. Results imply that examined confounding variables are similarly related to the measures of processing speed. Therefore, any of the measures of information processing speed considered in this study may be used as a proxy for the more direct measure of this construct derived from the Sternberg Memory Scanning Test.