The effects of mild and severe traumatic brain injury on speed of information processing as measured by the computerized tests of information processing (CTIP).

In spite of the fact that reaction time (RT) measures are sensitive to the effects of traumatic brain injury (TBI), few RT procedures have been developed for use in standard clinical evaluations. The computerized test of information processing (CTIP) [Tombaugh, T. N., & Rees, L. (2000). Manual for the computerized tests of information processing (CTIP). Ottawa, Ont.: Carleton University] was designed to measure the degree to which TBI decreases the speed at which information is processed. The CTIP consists of three computerized programs that progressively increase the amount of information that is processed. Results of the current study demonstrated that RT increased as the difficulty of the CTIP tests increased (known as the complexity effect), and as severity of injury increased (from mild to severe TBI). The current study also demonstrated the importance of selecting a non-biased measure of variability. Overall, findings suggest that the CTIP is an easy to administer and sensitive measure of information processing speed.     

Reaction time: An alternative method for assessing the effects of multiple sclerosis on information processing speed.

The ability of a newly developed measure of information processing to detect deficits in cognitive functioning associated with multiple sclerosis (MS) was investigated. The Computerized Tests of Information Processing (CTIP; Tombaugh, T., & Rees, L. (1999). Computerized Tests of Information Processing (CTIP). Unpublished test. Ottawa, Ontario, Canada: Carleton University) was administered to 60 clinically definite MS patients and 60 healthy controls. MS patients responded significantly slower than controls on the reaction time tests composing the CTIP. Moreover, as the CTIP tests became more difficult (i.e. as processing demands increased), the difference between the performances of the two groups progressively increased. These results suggest the CTIP is sensitive to the cognitive deficits observed in MS and that this measure has the potential to serve as a viable alternative to traditional measures of information processing speed currently in use with MS patients.     

Visual reaction time and its relationship to neuropsychological test performance.

The purpose of this study was to investigate the relationship between simple and choice reaction time (RT) measures and neuropsychological test performance (as assessed by the Impairment Index of the Halstead-Reitan Neuropsychological Test Battery). Both median RT scores and intraindividual variability of RT scores were evaluated in three groups: impaired TBI, nonimpaired TBI, and normal controls. In all three groups, there was a statistically significant correlation between both reaction time measures and level of cognitive functioning. In addition, SRT, speed of information processing (as measured by CRT), and intraindividual variability of RT scores continued to be impaired in many brain-damaged individuals who, according to the Impairment Index, had fully recovered from their cognitive deficits. Median RT scores were better able to discriminate between impaired TBI patients and normal controls; but intraindividual variability of RT scores was better able to discriminate between nonimpaired TBI patients and normal controls. It was concluded that, by adding the two short RT tests to the neuropsychological test battery, more accurate predictions can be made about a patient's level of cognitive functioning and the nature of treatment needed for continued recovery.     

The ability of reaction time tests to detect simulation: An investigation of contextual effects and criterion scores

Two experiments examined whether experience gained with a series of reaction time tests [Computerized Tests of Information Processing (CTIP); Tombaugh, T. N. & Rees, L. (in press). Computerized Tests of Information Processing (CTIP). Toronto, Canada: Multi-Health Systems Inc.] influenced the performance of individuals instructed to simulate the cognitive effects of a traumatic brain injury. Experience with the tests was manipulated by varying the order and number of tests administered for simulator and control groups. Simulators responded significantly slower and exhibited increased variability compared to controls. Performance was not affected by order or number of tests. The results of a third experiment showed that criterion scores could be established that correctly classified members of control, simulator, mild TBI, and severe TBI groups. Overall, the results suggest that the performance of the simulators was based on a context-free, absolute judgment and that reaction time measures show considerable promise for detecting low effort.     

Children's attentional skills 5 years post-TBI

OBJECTIVE: While a small number of research papers have reported findings on attentional deficits following pediatric traumatic brain injury (TBI), no study to date has reported findings in this area at 5 years post-TBI in very young children. This study examined attentional skills in a group of children who had sustained a mild, moderate, or severe TBI between the ages of 2 and 7 years. METHODS: The sample comprised 70 children, 54 of these had sustained a TBI and 16 the non-injured control group. Children were assessed 5 years post-TBI, with focus on tests of attentional ability. RESULTS: Attentional and processing speed (PS) deficits do occur and persist up to 5 years post-TBI, particularly following severe TBI in early childhood. Predictors of attentional outcomes varied depending on the component of attention investigated. CONCLUSIONS: Those skills developing or emerging at time of injury (e.g., sustained attention, shifting attention, divided attention, PS) are more compromised and may not develop at a normal rate of post-injury.     

A reevaluation of sustained attention performance in temporal lobe epilepsy.

Reports of normal Continuous Performance Test (CPT) accuracy in patients with temporal lobe epilepsy (TLE) stand in contrast to a demonstration of nonspecific absolute reaction time (RT) deficits in this population. In this study, we examined CPT data from a TLE sample for potential RT deficits across three consecutive blocks of time during the vigil. Seventeen patients with medically intractable epilepsy of temporal lobe origin and 17 healthy volunteers participated. The Conners CPT was used to assess sustained attention over a 14-min vigil. There were no significant group differences in accuracy. There was, however, a significant interaction between groups and time intervals, with disproportionate RT increases for patients at the end of the vigil. These findings are consistent with a report of nonspecific RT deficits in TLE despite normal accuracy scores, and further indicate impaired RT performance over time.     

Prenatal alcohol exposure causes attention deficits in male rats

Children with fetal alcohol spectrum disorder (FASD) are often diagnosed with attention-deficit/ hyperactivity disorder (ADHD). These children show increases in reaction time (RT) variability and false alarms on choice reaction time (CRT) tasks. In this study, adult rats prenatally exposed to ethanol were trained to perform a CRT task. An analysis of the distribution of RTs obtained from the CRT task found that rats with a history of prenatal ethanol exposure had more variable RT distributions, possibly because of lapses of attention. In addition, it was found that, similar to children with FASD, the ethanol-exposed rats had more false alarms. Thus, rats with prenatal ethanol exposure show attention deficits that are similar to those of children with FASD and ADHD.     

Changes in attention and information-processing speed following severe traumatic brain injury: a meta-analytic review

Deficits in attention are frequently reported following severe traumatic brain injury (TBI). However, methodological differences make it difficult to reconcile inconsistencies in the research findings in order to undertake an evidence-based assessment of attention. The current study therefore undertook a meta-analytic review of research examining attention following severe TBI. A search of the PsycINFO and PubMed databases spanning the years 1980 to 2005 was undertaken with 24 search terms. Detailed inclusion and exclusion criteria were used to screen all articles, leaving 41 studies that were included in the current meta-analysis. Weighted Cohen's d effect sizes, percentage overlap statistics, and confidence intervals were calculated for the different tests of attention. Fail-safe Ns were additionally calculated to address the bias introduced by the tendency to publish significant results. Large and significant deficits were found in specific measures of information-processing speed, attention span, focused/selective attention, sustained attention, and supervisory attentional control following severe TBI. Finally, age, education, and postinjury interval were not significantly related to these deficits in attention.     

Reactivity and event-related potentials during attentional tests in athletes

A series of attentional tests involving reaction times (RTs) was administered to 12 high-level young (age 17–18 years) volleyball players. During the tests, event-related potentials were recorded by electroencephalogram. In a simple reaction-time test (SRT), the subjects had to respond to a letter that appeared on a white screen. Other tests (attentional shifting tests) consisted of a go/no-go reaction time and a choice reaction time (CRT), divided into a short-latency CRT and a long-latency CRT. In the pre-stimulus period of these tests, there is a shift from broad attention to selective attention, represented by a crowding of black points on the computer screen, followed by the appearance of a letter in the centre of the crowding. The results show that RT increased from SRT to CRT. In the attentional shifting tests, averaged waves of event-related potentials showed a contingent-negative-variation-like wave that was closely related to selective attention (selective attention wave, SAW) before the onset of the stimulus. After the stimulus, a P3 complex was recorded. Correlations were found between the SAW amplitude and P3 latency and amplitude, and between these parameters and RT and its variability. Higher SAW and P3 amplitudes were accompanied by a shorter RT and a lower variability. The characteristics and the correlations that exist between the various parameters are consistent with a possible use of these tests in the analysis of the attentional styles of athletes, and in the evaluation of their progress with training.     

Brain imaging correlates of verbal working memory in children following traumatic brain injury

Neural correlates of working memory (WM) based on the Sternberg Item Recognition Task (SIRT) were assessed in 40 children with moderate-to-severe traumatic brain injury (TBI) compared to 41 demographically-comparable children with orthopedic injury (OI). Multiple magnetic resonance imaging (MRI) methods assessed structural and functional brain correlates of WM, including volumetric and cortical thickness measures on all children; functional MRI (fMRI) and diffusion tensor imaging (DTI) were performed on a subset of children. Confirming previous findings, children with TBI had decreased cortical thickness and volume as compared to the OI group. Although the findings did not confirm the predicted relation of decreased frontal lobe cortical thickness and volume to SIRT performance, left parietal volume was negatively related to reaction time (RT). In contrast, cortical thickness was positively related to SIRT accuracy and RT in the OI group, particularly in aspects of the frontal and parietal lobes, but these relationships were less robust in the TBI group. We attribute these findings to disrupted fronto-parietal functioning in attention and WM. fMRI results from a subsample demonstrated fronto-temporal activation in the OI group, and parietal activation in the TBI group, and DTI findings reflected multiple differences in white matter tracts that engage fronto-parietal networks. Diminished white matter integrity of the frontal lobes and cingulum bundle as measured by DTI was associated with longer RT on the SIRT. Across modalities, the cingulate emerged as a common structure related to performance after TBI. These results are discussed in terms of how different imaging modalities tap different types of pathologic correlates of brain injury and their relationship with WM.     

The construct of problem solving in higher level neuropsychological assessment and rehabilitation.

Three inter-related studies examine the construct of problem solving as it relates to the assessment of deficits in higher level outpatients with traumatic brain injury (TBI). Sixty-one persons with TBI and 58 uninjured participants completed measures of problem solving and conceptually related constructs, which included neuropsychological tests, self-report inventories, and roleplayed scenarios. In Study I, TBI and control groups performed with no significant differences on measures of memory, reasoning, and executive function, but medium to large between-group differences were found on timed attention tasks. The largest between-group differences were found on psychosocial and problem-solving self-report inventories. In Study II, significant-other (SO) ratings of patient functioning were consistent with patient self-report, and for both self-report and SO ratings of patient problem solving, there was a theoretically meaningful pattern of correlations with timed attention tasks. In Study III, a combination of self-report inventories that accurately distinguished between participants with and without TBI, even when cognitive tests scores were in the normal range, was determined. The findings reflect intrinsic differences in measurement approaches to the construct of problem solving and suggest the importance of using a multidimensional approach to assessment.     

Stopping and changing in adults with ADHD

BACKGROUND: A lack of inhibitory control has been suggested to be the core deficit in children with attention deficit hyperactivity disorder (ADHD). This means that a primary deficit in behavioral inhibition mediates a cascade of secondary deficits in other executive functions, such as arousal regulation. Clinical observations have revealed that with increasing age symptoms of hyperactivity and impulsivity decline at a higher rate than those of inattention. This might imply that a deficit in attention rather than a lack of inhibitory control is the major feature in adult ADHD. METHOD: To study whether an attentional or inhibitory deficit predominates, the stop-signal task and the stop-change task were presented to 24 adults with ADHD combined subtype and 24 controls. RESULTS: Relative to controls, the stop-signal reaction time (SSRT) was significantly more prolonged than the go-stimulus reaction time (RT) in patients with ADHD. This disproportionate elongation of the SSRT was comparable across tasks, even though the stop-change task exerted more complex (or at least different) demands on the inhibitory system than the stop-signal task. ADHD patients had a higher proportion of choice errors, possibly reflecting more premature responses. Specifically in the stop-change task, patients had more variable choice responses and made more inappropriate change responses, which may also reflect enhanced impulsivity. CONCLUSIONS: The results support a core deficit in behavioral inhibition in adults with ADHD. We further suggest that there is more evidence for a critical role of deficient inhibitory control in adults than in children with ADHD.     

Sustained attention in traumatic brain injury (tbi) and healthy controls: enhanced sensitivity with dual-task load

Poor sustained attention or alertness is a common consequence of traumatic brain injury (TBI) and has a considerable impact on the recovery and adjustment of TBI patients. Here, we describe the development of a sensitive laboratory task in healthy subjects (Experiment 1) and its enhanced sensitivity to sustained attention errors in TBI patients (Experiment 2). The task involves withholding a key press to an infrequent no-go target embedded within a predictable sequence of numbers (primary goal) and detecting grey-coloured targets within the sequence (secondary goal). In Experiment 1, we report that neurologically healthy subjects are more likely to experience a lapse of attention and neglect the primary task goal, despite ceiling performance on the secondary task. Further, attentional lapses on the task correlated with everyday attentional failures and variability of response time. In Experiment 2, the task discriminates between TBI patients and controls with a large effect size. The dual-task yields more errors in both groups than a simple task involving only the primary goal that is commonly used to detect sustained attention deficits in neurologically impaired groups. TBI patients' errors also correlated with everyday cognitive failures and variability of response time. This was not the case in the simple version of the task. We conclude that the dual-task demand associated with this task enhances its sensitivity as a measure of sustained attention in TBI patients and neurologically healthy controls that relates to everyday slips of attention.     

Simple and choice reaction time in dementia: Clinical implications

The present study investigated differences between normal elderly subjects matched for age and education and patients with dementia of the Alzheimer's type (DAT) on two measures of reaction time (RT). Statistically significant group differences clearly demonstrate that normal elderly subjects have faster RT than subjects with senile dementia on all RT tasks. The DAT patients were most clearly differentiated in terms of overall group means and clinical classification from their age-matched counterparts on the choice RT task. Eleven of 12 (92%) DAT patients displayed choice RT's 2 or more standard deviations above those of age-matched normals. While both RT measures were discriminative between patients and normals, the overall results argue for increased sensitivity when choice is required in RT in accessing the cognitive deficits in DAT.     

Prospective Memory in Pediatric Traumatic Brain Injury: A Preliminary Study

Prospective memory (PM) performance was investigated in a preliminary study of children and adolescents ages 10-19 in 3 groups: individuals with orthopedic injuries (not involving the head) requiring hospitalization (Ortho, N = 15), mild traumatic brain injury (TBI, N = 17), and severe TBI (N = 15). All participants with TBI were at least 5 years postinjury and participants in the Ortho group were at least 3 years postinjury. The PM task involved reporting words presented in blue during a category decision task in which words were presented in several different colors and participants were to determine which of two categories the word belonged. Participants were asked to make their choices as quickly as possible. After a 10- to 15-min intervening computer task in which all words were presented in black letters, a large proportion of participants with mild or severe TBI failed to indicate any blue words when they appeared. After a reminder to perform the PM task was given to all at the same point in the task, PM performance increased in the Ortho and Mild TBI groups, but remained comparably impaired in the Severe TBI group. Reaction time (RT) data indicated that mean RT was slower with increasing TBI severity. Further, there was a significant cost in RT for performing the PM task during the ongoing category decision task for all groups. The cost in terms of slowed RT increased with greater TBI severity.     

Prospective Memory in Pediatric Traumatic Brain Injury: A Preliminary Study

Prospective memory (PM) performance was investigated in a preliminary study of children and adolescents ages 10-19 in 3 groups: individuals with orthopedic injuries (not involving the head) requiring hospitalization (Ortho, N = 15), mild traumatic brain injury (TBI, N = 17), and severe TBI (N = 15). All participants with TBI were at least 5 years postinjury and participants in the Ortho group were at least 3 years postinjury. The PM task involved reporting words presented in blue during a category decision task in which words were presented in several different colors and participants were to determine which of two categories the word belonged. Participants were asked to make their choices as quickly as possible. After a 10- to 15-min intervening computer task in which all words were presented in black letters, a large proportion of participants with mild or severe TBI failed to indicate any blue words when they appeared. After a reminder to perform the PM task was given to all at the same point in the task, PM performance increased in the Ortho and Mild TBI groups, but remained comparably impaired in the Severe TBI group. Reaction time (RT) data indicated that mean RT was slower with increasing TBI severity. Further, there was a significant cost in RT for performing the PM task during the ongoing category decision task for all groups. The cost in terms of slowed RT increased with greater TBI severity.     

Prospective memory in pediatric traumatic brain injury: a preliminary study

Prospective memory (PM) performance was investigated in a preliminary study of children and adolescents ages 10-19 in 3 groups: individuals with orthopedic injuries (not involving the head) requiring hospitalization (Ortho, N = 15), mild traumatic brain injury (TBI, N = 17), and severe TBI (N = 15). All participants with TBI were at least 5 years postinjury and participants in the Ortho group were at least 3 years postinjury. The PM task involved reporting words presented in blue during a category decision task in which words were presented in several different colors and participants were to determine which of two categories the word belonged. Participants were asked to make their choices as quickly as possible. After a 10- to 15-min intervening computer task in which all words were presented in black letters, a large proportion of participants with mild or severe TBI failed to indicate any blue words when they appeared. After a reminder to perform the PM task was given to all at the same point in the task, PM performance increased in the Ortho and Mild TBI groups, but remained comparably impaired in the Severe TBI group. Reaction time (RT) data indicated that mean RT was slower with increasing TBI severity. Further, there was a significant cost in RT for performing the PM task during the ongoing category decision task for all groups. The cost in terms of slowed RT increased with greater TBI severity.     

Psychomotor performance deficits and their relation to prior nights' sleep among individuals with primary insomnia

OBJECTIVE: To examine psychomotor (reaction time) performance deficits and their relation to subjective and objective sleep measures among individuals with primary insomnia (PI). DESIGN AND SETTING: This study was conducted at affiliated VA and academic medical centers using a matched-groups, cross-sectional research design. PARTICIPANTS: Seventy-nine (43 women) individuals with PI (MAge = 50.0 +/- 17.1 y) and 84 (41 women) well-screened normal sleepers (MAge = 48.6 +/- 16.8 y). METHODS AND MEASURES: Participants underwent 3 nights of polysomnography (PSG) followed by daytime testing with a 4-trial multiple sleep latency test (MSLT). Before each MSLT nap, they rated their sleepiness and completed a performance battery that included simple reaction time (SRT), continuous performance (CPT), and 4 switching attention (SAT) tests. Performance measures included the mean response latency and the standard deviation of each subject's within-test response latencies. RESULTS: PI sufferers reported greater (P = 0.001) daytime sleepiness, but were significantly (P = 0.02), more alert than normal sleepers on the MSLT. Multivariate analyses showed the PI group had significantly longer response latencies and greater response variability across many of the subtests than did the controls. Regression analyses showed that both PSG- and diary-based sleep measures contributed to the prediction of daytime performance indices, although objective wake time after sleep onset appeared the best single predictor of the daytime measures. CONCLUSIONS: Results confirm that PI sufferers do show relative psychomotor performance deficits when responding to challenging reaction time tasks, and these deficits appear related to both objective and subjective sleep deficits. Findings support PI patients' diurnal complaints and suggest the usefulness of complex reaction time tasks for assessing them.     

高特质焦虑情绪大学生对威胁刺激的选择性注意抑制

目的:探究高特质焦虑情绪大学生的选择性注意抑制功能。方法:通过特质焦虑问卷筛选出高、低特质焦虑情绪大学生各20名,采用改进的情绪负启动范式,以语义判断的情绪负启动任务,考察高特质焦虑情绪大学生的注意抑制能力。结果:低特质焦虑情绪组在负启动条件下,对威胁和中性词汇的反应时都显著大于控制条件下;高特质焦虑情绪组在负启动条件下,对威胁词汇的反应时显著小于控制条件下,中性词汇的反应时与控制条件之间差异不显著。对中性词汇,高、低特质焦虑情绪组的负启动量差异不显著;对威胁词汇,高特质焦情绪组负启动量显著小于低特质焦虑情绪组。结论:高特质焦虑情绪大学生对威胁刺激表现出负启动效应减弱,存在特定威胁信息的注意抑制困难。     

Attentional, emotional and hormonal data in subjects of different ages

The differences in attentional style among subjects of different ages and the influence of emotionality on the attentional components were studied for a limited experimental period. Variation in the hormonal data and its relation to behavioural parameters were also evaluated. The subjects enrolled in the study were divided into four age groups (A 18–29, B 30–45, C 46–59, D 60–77 years). The attentional tests involved different types of attention: alert, go/no-go, divided attention and working memory. Emotionality was assessed on the basis of skin conductance, heart rate and frontalis muscle tone. Testosterone (T), free testosterone (fT), non-specifically bound testosterone (NST), sex hormone binding globulin (sHBG), oestradiol, cortisol and adrenocorticotrophic hormone were determined in the plasma. The data were analysed to identify endocrine and behavioural differences related to sex and age. The results showed an influence of age on reaction time (RT) and RT variability. This was particularly evident for groups C and D with respect to A in the simple (alert) and complex RT tests (go/no-go and working memory). Divided attention, with the highest RT, showed a clear distinction between group A and the other groups. The difference in frontalis electromyography (EMG) (test vs control) increased with age, while the autonomic responses (skin conductance and heart rate) did not vary. In most attentional tests, the age-related reduction of RT was associated with increased T, fT and NST and decreased cortisol.