Neurobehavioural performance of adults with closed-head injury, adults with attention deficit, and controls

Applications of the Morris water maze in translational traumatic brain injury research

Acquired traumatic brain injury (TBI) is frequently accompanied by persistent cognitive symptoms, including executive function disruptions and memory deficits. The Morris Water Maze (MWM) is the most widely-employed laboratory behavioral test for assessing cognitive deficits in rodents after experimental TBI. Numerous protocols exist for performing the test, which has shown great robustness in detecting learning and memory deficits in rodents after infliction of TBI. We review applications of the MWM for the study of cognitive deficits following TBI in pre-clinical studies, describing multiple ways in which the test can be employed to examine specific aspects of learning and memory. Emphasis is placed on dependent measures that are available and important controls that must be considered in the context of TBI. Finally, caution is given regarding interpretation of deficits as being indicative of dysfunction of a single brain region (hippocampus), as experimental models of TBI most often result in more diffuse damage that disrupts multiple neural pathways and larger functional networks that participate in complex behaviors required in MWM performance.

The effect of premorbid attention-deficit/hyperactivity disorder on neuropsychological functioning in individuals with acute mild traumatic brain injuries

INTRODUCTION

Mild traumatic brain injury (mTBI) is a frequent, yet undertreated condition that typically manifests with transient neurological and cognitive symptoms that resolve over the course of several weeks. In contrast, attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that presents initially in childhood but often persists into adulthood. mTBI and ADHD include overlapping symptomatology, making it difficult for clinicians to disentangle the sequelae of each condition when they co-occur in the same individual. We hypothesized that neuropsychological tests would be sensitive to preexisting ADHD in inpatients with acute mTBIs.

METHOD

We retrospectively examined the medical charts of 100 inpatients, aged 18-40 years (96% Caucasian; 77% male) with mTBIs in an acute care setting, half of whom had self-reported the presence of premorbid ADHD, and half of whom were matched controls. We analyzed group differences across neuropsychological tests of attention, processing speed, and executive functions, examined the profile ratings of independent, blinded, board-certified neuropsychologists, and correlated cognitive performance with time from traumatic injury to testing.

RESULTS

Individuals with premorbid ADHD (a) performed significantly worse than their matched counterparts on several tests of attention, processing speed, and working memory, and (b) were significantly more likely to produce profiles later rated as impaired by independent, board-certified clinical neuropsychologists. In addition, time from traumatic injury to testing was found to be negatively correlated with neurocognitive performance.

CONCLUSIONS

These findings (a) argue for the utility of a brief assessment of premorbid ADHD in the acute care of individuals with mTBIs and (b) provide clinicians with a barometer for gauging the relative contributions of premorbid ADHD to neuropsychological impairments in the neurocognitive profiles of individuals with mTBIs. Reported effect sizes will assist clinicians in accurately weighing the impact of premorbid ADHD when interpreting such profiles.

Intraindividual variability in inhibitory function in adults with ADHD--an ex-Gaussian approach

OBJECTIVE

Attention deficit disorder (ADHD) is commonly associated with inhibitory dysfunction contributing to typical behavioral symptoms like impulsivity or hyperactivity. However, some studies analyzing intraindividual variability (IIV) of reaction times in children with ADHD (cADHD) question a predominance of inhibitory deficits. IIV is a measure of the stability of information processing and provides evidence that longer reaction times (RT) in inhibitory tasks in cADHD are due to only a few prolonged responses which may indicate deficits in sustained attention rather than inhibitory dysfunction. We wanted to find out, whether a slowing in inhibitory functioning in adults with ADHD (aADHD) is due to isolated slow responses.

METHODS

Computing classical RT measures (mean RT, SD), ex-Gaussian parameters of IIV (which allow a better separation of reaction time (mu), variability (sigma) and abnormally slow responses (tau) than classical measures) as well as errors of omission and commission, we examined response inhibition in a well-established GoNogo task in a sample of aADHD subjects without medication and healthy controls matched for age, gender and education.

RESULTS

We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls. In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD. However, subjects with aADHD were characterized by increased IIV throughout the entire RT distribution as indicated by the parameters sigma and tau as well as the SD of reaction time. Moreover, we found a significant correlation between tau and the number of omission errors.

CONCLUSIONS

Our findings question a primacy of inhibitory deficits in aADHD and provide evidence for attentional dysfunction. The present findings may have theoretical implications for etiological models of ADHD as well as more practical implications for neuropsychological testing in aADHD.

Attention deficit hyperactivity disorder and athletes

CONTEXT

Attention deficit hyperactivity disorder (ADHD) is common in the general population, and many individuals with this condition participate in sports activity at all competition levels.

EVIDENCE ACQUISITION

Related studies were selected through literature searches of PubMed, MEDLINE, and Cochrane databases for the years 1991 to 2011. Key search terms were ADD, ADHD, sports, athletes, athletics, guidelines, NCAA, WADA, IOC, college, concussion, diagnosis, management, treatment, evaluation, return-to-play, pharmacotherapy, adult, adolescent, student, screening, injury, risk, neuropsychiatry, TBI, traumatic brain injury, and epidemiology.

STUDY DESIGN

Literature review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

ADHD usually has an early onset, with delayed diagnosis in some patients due to heterogeneous presentations. Suspected cases can be evaluated with available diagnostic tools and confirmed clinically. Athletes with ADHD may participate at all competition levels.

CONCLUSION

Athletes with ADHD are able to participate at all competition levels by following published guidelines and requirements. Exercise benefits many athletes with ADHD. The relationship between ADHD and concussion syndromes is currently under investigation.

Differential effects of methylphenidate on problem solving in adults with ADHD

OBJECTIVE

Two studies were performed to assess both divergent and convergent thinking in adults with ADHD.

METHOD

The first study compared the problem-solving abilities of healthy participants (N = 144) and unmedicated adults with ADHD (N = 144). In the second study, problem-solving abilities of adults with diagnosed ADHD (N = 22) were examined twice, that is, on and off methylphenidate (MPH), and compared with the performance of a healthy control group (N = 22). Convergent thinking was measured using a Tower of London task, whereas divergent thinking was assessed using verbal fluency tasks.

RESULTS

Adults with ADHD off MPH displayed marked deficits of both divergent and convergent thinking. MPH treatment resulted in a marked improvement of convergent thinking, while no effect of medication was found regarding divergent thinking.

CONCLUSION

Pharmacological treatment of adults with ADHD revealed a differential effect of MPH on problem solving abilities.

Diffusion tensor imaging of mild traumatic brain injury

Mild traumatic brain injury (mTBI) remains a challenge to accurately assess with conventional neuroimaging. Recent research holds out the promise that diffusion tensor imaging (DTI) can be used to predict recovery in mTBI patients. Unlike computed tomography or conventional magnetic resonance imaging, DTI is sensitive to microstructural axonal injury, the neuropathology that is thought to be most responsible for the persistent cognitive and behavioral impairments that often occur after mTBI. Through the use of newer DTI analysis techniques such as automated region of interest analysis, tract-based voxel-wise analysis, and quantitative tractography, researchers have shown that frontal and temporal association white matter pathways are most frequently damaged in mTBI and that the microstructural integrity of these tracts correlates with behavioral and cognitive measures. Future longitudinal DTI studies are needed to elucidate how symptoms and the microstructural pathology evolve over time. Moving forward, large-scale investigations will ascertain whether DTI can serve as a predictive imaging biomarker for long-term neurocognitive deficits after mTBI that would be of value for triaging patients to clinical trials of experimental cognitive enhancement therapies and rehabilitation methods, as well as for monitoring their response to these interventions.

Attention processing abnormalities in children with traumatic brain injury and attention-deficit/hyperactivity disorder: differential impairment of component processes

Individuals with acquired and neurodevelopmental brain disorders often exhibit deficits in attention. Recent models of attention have conceptualized it as a multicomponent system. One influential model proposed by Mirsky et al. (1991) consists of factors that include focus, sustain, shift, and encode components. This model has been used to examine the structure of attention in a variety of clinical populations although few studies have contrasted performance of various clinical groups in order to determine whether these components are differentially affected. To address this issue, the current study investigated the differential sensitivity of these attention components in 90 children: 30 who had sustained traumatic brain injury (TBI), 30 who were diagnosed with attention-deficit/hyperactivity disorder (ADHD), and 30 normal controls. Results demonstrated that the TBI group had significantly lower focus factor scores, the ADHD group had significantly lower sustain scores, and that both clinical groups had lower encode factor scores than controls. Stepwise discriminant function analysis (DFA) retained the focus and encode factors in predicting clinical groups from controls with 75.6% accuracy. A second DFA retained the focus factor in differentiating the two clinical groups with 70.0% accuracy. These findings provide evidence of differential attention deficits resulting from TBI and ADHD.

Validation of the Behavioral Dyscontrol Scale-Electronic Version: Sensitivity to subtle sequelae of mild traumatic brain injury

PRIMARY OBJECTIVE

To determine whether a new computer-administered battery (Behavioral Dyscontrol Scale-Electronic Version; BDS-EV) can detect subtle executive weaknesses among individuals with a self-reported history of mild head trauma (MHT), and to compare the utility of this battery to the original, non-electronic BDS and other traditional executive measures. Both BDS-EV and BDS are comprised of three factors (motor programming, environmental independence, and fluid intelligence).

METHOD

Participants with (n = 19) and without (n = 24) MHT were compared on their performance on the BDS-EV, the non-electronic BDS, and three traditional measures of executive abilities.

RESULTS

Participants with MHT differed from those without MHT on the BDS-EV motor programming and environmental independence, but not on any other measures.

CONCLUSION

The results show that electronic administration improved the sensitivity of the battery, and support prior findings that traditional executive measures are generally insensitive to subtle executive deficits associated with chronic MHT.

Vigilance and sustained attention in children and adults with ADHD

OBJECTIVE

The present article tests the hypothesis of a sustained attention deficit in children and adults suffering from ADHD.

METHOD

Vigilance and sustained attention of 52 children with ADHD and 38 adults with ADHD were assessed using a computerized vigilance task. Furthermore, the attentional performance of healthy children (N = 52) and healthy adults (N = 38) was examined.

RESULTS

Children and adults with ADHD performed significantly less well in the vigilance task than healthy participants (main effect for group). Furthermore, children and adults showed a significant decrease of performance over time (time-on-task effects). However, there was no greater decrement of performance with the passage of time in patient groups than in control groups (group-by-time interaction).

CONCLUSION

The present results do not support the hypothesis of a sustained attention deficit in children and adults with ADHD.

Focal lesions in acute mild traumatic brain injury and neurocognitive outcome: CT versus 3T MRI

Mild traumatic brain injury (mTBI) is associated with long-term cognitive deficits. This study compared the detection rate of acute post-traumatic focal lesions on computed tomography (CT) and 3T (Tesla) magnetic resonance (MR) imaging with neurocognitive outcomes. Adults (n = 36; age range, 19-52 years) with a single episode of mTBI (Glasgow Coma Scale 13-15, as well as loss of consciousness and post-traumatic amnesia) were prospectively enrolled and had CT within 24 h of injury and 3T MR within 2 weeks of injury. The CT and MR scans were reviewed by two neuroradiologists who were blinded to clinical information. Twenty-eight of these mTBI subjects and 18 matched healthy volunteers also underwent serial neurocognitive testing. Of the 36 mTBI cases, intraparenchymal lesions were detected in 18 CT and 27 acute MR exams, consisting of hemorrhagic traumatic axonal injury (TAI) (eight CT, 17 MR), non-hemorrhagic TAI (zero CT, four MR), and cerebral contusions (13 CT, 21 MR). Mild TBI patients had significantly worse performance on working memory tasks than matched controls at the acute time point (<2 weeks), and at 1 month and at 1 year post-injury; yet there was no significant correlation of imaging findings with working memory impairment. In conclusion, 3T MR detected parenchymal lesions in 75% of this mTBI cohort with loss of consciousness and post-traumatic amnesia, a much higher rate than CT. However, the CT and 3T MR imaging findings did not account for cognitive impairment, suggesting that newer imaging techniques such as diffusion tensor imaging are needed to provide biomarkers for neurocognitive and functional outcome in mTBI.

Go-no-go performance in pathological gamblers

Previous neuropsychological studies demonstrated various deficits of impulse control in pathological gamblers (PGs). However, there are limited data available on response-inhibition impairment among PGs. The present study attempted to assess response inhibition in untreated PGs (N=83), in comparison with normal subjects (N=84). Go/no-go and target-detection conditions of a computerized task were used as a measure of response-inhibition ability. A repeated measures analysis of covariance (ANCOVA-RM) was used with response time, variability of response time, and number of false alarms and misses as dependent measures; group (PG and controls) as the between-subjects measure; condition (target detection or go/no-go) and time slice (first and second in each condition) as repeated measures within-subject factors; and educational level as a covariate. Our results showed that PGs were significantly more impaired in both target detection and go/no-go task performance than controls. The PGs had significantly more false alarms and misses than controls, and they were slower and less consistent in their responses.

Structural dissociation of attentional control and memory in adults with and without mild traumatic brain injury

Memory and attentional control impairments are the two most common forms of dysfunction following mild traumatic brain injury (TBI) and lead to significant morbidity in patients, yet these functions are thought to be supported by different brain networks. This 3 T magnetic resonance diffusion tensor imaging (DTI) study investigates whether microstructural integrity of white matter, as measured by fractional anisotropy (FA) within a small set of individually localized regions of interest (ROIs), is associated with these cognitive domains in normal adults and adults with mild TBI. Results in a sample of 23 normal controls reveal a significant correlation between attentional control and FA within a ROI in the left hemisphere anterior corona radiata. Furthermore, the controls demonstrate a correlation between memory performance and FA in a ROI placed in the uncinate fasciculus. Next, to examine whether these relationships are found in the pathological ranges of attention, memory and microstructural white matter integrity associated with mild TBI, these analyses were applied to a group of 43 mild TBI patients. Results, which generally demonstrated a wider range of attention, memory and FA scores, replicated the correlation between attentional control and FA in left hemisphere anterior corona radiata, as well as the correlation between memory performance and FA in the uncinate fasciculus. These two sets of brain-behaviour relationships were highly specific, as shown by a lack of correlation between attention and uncinate fasciculus FA and the lack of correlation between memory performance and anterior corona radiata FA. Furthermore, a 'correlational double dissociation' was demonstrated to exist between two distinct frontal structures independently associated with attention and memory, respectively, via a series of multiple regression analyses in both normal controls and adults with mild TBI. The results of the multiple regression analyses provide direct evidence that tract-specific variation in microstructural white matter integrity among normal controls and among mild TBI patients can account for much of the variation in performance in specific cognitive domains. More generally, such findings suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for neurocognitive function and dysfunction.

Extent of microstructural white matter injury in postconcussive syndrome correlates with impaired cognitive reaction time: a 3T diffusion tensor imaging study of mild traumatic brain injury

BACKGROUND AND PURPOSE

Diffusion tensor imaging (DTI) may be a useful index of microstructural changes implicated in diffuse axonal injury (DAI) linked to persistent postconcussive symptoms, especially in mild traumatic brain injury (TBI), for which conventional MR imaging techniques may lack sensitivity. We hypothesized that for mild TBI, DTI measures of DAI would correlate with impairments in reaction time, whereas the number of focal lesions on conventional 3T MR imaging would not.

MATERIALS AND METHODS

Thirty-four adult patients with mild TBI with persistent symptoms were assessed for DAI by quantifying traumatic microhemorrhages detected on a conventional set of T2*-weighted gradient-echo images and by DTI measures of fractional anisotropy (FA) within a set of a priori regions of interest. FA values 2.5 SDs below the region average, based on a group of 26 healthy control adults, were coded as exhibiting DAI.

RESULTS

DTI measures revealed several predominant regions of damage including the anterior corona radiata (41% of the patients), uncinate fasciculus (29%), genu of the corpus callosum (21%), inferior longitudinal fasciculus (21%), and cingulum bundle (18%). The number of damaged white matter structures as quantified by DTI was significantly correlated with mean reaction time on a simple cognitive task (r = 0.49, P = .012). In contradistinction, the number of traumatic microhemorrhages was uncorrelated with reaction time (r = -0.08, P = .71).

CONCLUSION

Microstructural white matter lesions detected by DTI correlate with persistent cognitive deficits in mild TBI, even in populations in which conventional measures do not. DTI measures may thus contribute additional diagnostic information related to DAI.

Intra-subject variability in attention-deficit hyperactivity disorder

BACKGROUND

This study is based on a comprehensive survey of the neuropsychological attention-deficit hyperactivity disorder (ADHD) literature and presents the first psychometric analyses of different parameters of intra-subject variability (ISV) in patients with ADHD compared to healthy controls, using the Continuous Performance Test, a Go-NoGo task, a Stop Signal Task, as well as N-back tasks.

METHODS

Data of 57 patients with ADHD and 53 age- and gender-matched controls were available for statistical analysis. Different parameters were used to describe central tendency (arithmetic mean, median), dispersion (standard deviation, coefficient of variation, consecutive variance), and shape (skewness, excess) of reaction time distributions, as well as errors (commissions and omissions).

RESULTS

Group comparisons revealed by far the strongest effect sizes for measures of dispersion, followed by measures of central tendency, and by commission errors. Statistical control of ISV reduced group differences in the other measures substantially. One (patients) or two (controls) principal components explained up to 67% of the inter-individual differences in intra-individual variability.

CONCLUSIONS

Results suggest that, across a variety of neuropsychological tests, measures of ISV contribute best to group discrimination, with limited incremental validity of measures of central tendency and errors. Furthermore, increased ISV might be a unitary construct in ADHD.

Methylphenidate-induced improvements of various measures of attention in adults with attention deficit hyperactivity disorder

The present study examined the effect of the stimulant medication methylphenidate (MPH) on attentional functioning of adults with ADHD. Sixteen adults with a diagnosed ADHD without comorbidity were assessed twice, at baseline off MPH and following MPH treatment. The assessment battery consisted of reaction time tasks of low complexity, including measures of alertness--subdivided into tonic and phasic alertness, vigilance, divided attention, flexibility and such aspects of selective attention as including focused attention, inhibition and integration of sensory information. In addition, 16 healthy participants who were matched to adults with ADHD according to sex, age, education level and intellectual functions were also assessed twice using the same test battery. The results of the present study suggest that adults with ADHD off stimulant medication are seriously impaired in various components of attention including vigilance, divided attention, selective attention and flexibility. These impairments of attention were observed primarily in regard to reaction time and its variability. Treatment of adults with ADHD using individually tailored doses of MPH has a positive effect on measures of alertness, vigilance, selective attention, divided attention and flexibility. However, even on MPH adults with ADHD displayed considerable deficits in vigilance and integration of sensory information. The present findings indicate that adults with ADHD are not differentially impaired in attentional processes but may suffer from a more global deficit of attention. Although MPH treatment has been found to be effective in the treatment of the attention deficit of adults with ADHD, additional treatment appears to be necessary.

Diffusion tensor imaging in chronic head injury survivors: correlations with learning and memory indices

Diffusion tensor imaging (DTI) provides a unique insight into the cellular integrity of the brain. While conventional magnetic resonance imaging underestimates the extent of pathology following closed head injury, diffusion-weighted imaging has been shown to more accurately delineate the extent of cerebral damage. There have only been a few case studies of DTI in chronic head injury survivors. This study used DTI to investigate changes in anisotropy and diffusivity in survivors of head injury at least 6 months after their injury. The relationship between cognition and diffusion abnormality was also investigated. The voxel-based analysis revealed significant bilateral decreases in anisotropy, in major white matter tracts and association fibers in the temporal, frontal, parietal and occipital lobes. Statistically significant increases in diffusivity were also found in widespread areas of the cortex. A significant positive correlation was found between diffusivity and impairment of learning and memory in the left posterior cingulate, left hippocampal formation and left temporal, frontal and occipital cortex. The common pattern of abnormality despite heterogeneous injury mechanism and lesion location in the group suggests that these cellular changes reflect secondary insults. The importance of diffusion abnormalities in head injury outcome is emphasized by the significant correlation between a learning and memory index and diffusivity in areas known to subserve this cognitive function.

Neurocognitive testing supports a broader concept of mild cognitive impairment

The narrow concept of mild cognitive impairment (MCI) as an early form of Alzheimer s disease has been broadened by research that established the existence of alternative forms of the condition that may presage other forms of dementia. The research presented here was a naturalistic, cross-sectional study of patients in a community referral clinic-patients with MCI and mild dementia-compared to normal controls. A comprehensive, computerized neurocognitive screening battery developed by one of the authors (CNS Vital Signs) was administered to all of the subjects. Participants consisted of 36 patients with MCI and 53 patients with mild dementia, diagnosed by standard criteria, and 89 matched normal controls. Multivariate analysis indicated significant differences among the three groups for all 15 primary test variables and for all five of the domain scores. Tests of memory, processing speed, and cognitive flexibility were the most cogent discriminators between normal controls and MCI patients, and between MCI patients and patients with mild dementia. The same three tests also had the greatest sensitivity and specificity. The results of this study indicate that computerized testing can differentiate among normal controls, MCI patients, and patients with mild dementia. Also, in a diverse group of MCI and mild dementia patients, impairments in memory, processing speed, and cognitive flexibility were the most prominent observed deficits.

Deficits in decision-making in head injury survivors

Many survivors of head injury suffer chronic personality changes, such as increased impulsivity and a lack of insight and poor judgment. These changes are well recognized and likely to affect the ability to make decisions. However, systematic investigations into their nature have been limited. This study aims to explore the nature of decision making in head injury survivors using a computerized task. Forty-three head injury survivors and a group of 29 matched controls completed the computerized task. The task required participants to make a probability-based choice and to further qualify this choice with an associated "bet." This betting component allows an assessment of the participant's level of confidence in the decision, via the affective evaluation of its possible consequences in terms of points won or lost. The survivors were found to be slow at making the probability- based choice. Whilst at highly favorable odds, the survivors chose the most likely option in a similar manner to the controls, they chose the most likely option less often than the controls at less favorable odds. Examination of the survivors' betting behavior revealed that they responded impulsively compared to controls. This pattern of prolonged decision making and poor quality of decisions is similar to that found in patients with orbitofrontal cortex lesions, whilst impulsive betting has been associated with abnormalities of the dopamine system. These complex deficits in decision making may contribute to difficulties with poor judgment and inhibition in head injury survivors.

Cognitive outcome in traumatic brain injury survivors

PURPOSE OF REVIEW

This review discusses recent studies investigating the cognitive and psychiatric outcome of posttraumatic brain injury. In addition, it aims to highlight key areas for future research.

RECENT FINDINGS

Detailed cognitive assessments have revealed particular deficits in processing speed in the visual domain and the detrimental impact of interference on attentional performance. A pilot functional imaging study revealed neural changes in survivors performing a response inhibition task, even when matched to controls on behavioural indices. Recent psychiatric studies highlight the incidence of these disorders in the survivors and attempt to characterize distinct psychiatric profiles. Adult and child survivors appear to show differential difficulties. Successful rehabilitation strategies addressing these psychiatric and cognitive deficits include holistic intensive neuropsychological interventions and the introduction of electronic devices. Systematic randomized trials are needed to provide an adequate evidence base for clinical practice. The potential for cognitive enhancement using psychopharmacological agents has yet to be exploited. These treatments may lead to improved quality of life for traumatic brain injury survivors and their families.

SUMMARY

Survivors of head injury show a diverse pattern of cognitive and psychiatric profiles. Recent research highlights the nature of some of these deficits and possible ways to enhance functioning. However, the area is well poised for rapid progress in the understanding of cognitive and emotional dysfunction following traumatic brain injury (TBI) and its rehabilitation through neuropsychological and psychopharmacological means.

The utility of self-report measures and the continuous performance test in the diagnosis of ADHD in adults

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) occurs in as many as 4 percent of adults yet it is often not recognized in clinical settings because the presenting symptoms may resemble those seen in other disorders or because symptoms may be masked by commonly comorbid conditions such as anxiety and depression.

OBJECTIVE

The purpose of this study was to examine the diagnostic utility of instruments commonly used in the assessment of adults presenting with symptoms of ADHD.

METHODS

We reviewed several widely used self-report and laboratory measures and empirically examined the utility of the Brown Attention-Deficit Disorder Scale for Adults (Brown ADD Scale) and the Conners Continuous Performance Test (CPT) in differentially identifying adults with ADHD and those with other Axis I disorders.

RESULTS

Ninety-three adults who self-referred to the ADHD program for adults at a university medical center participated in the study. Of these, 44 had ADHD combined subtype (ADHD-CB), and 26 had ADHD, predominantly inattentive subtype (ADHD-IA). Thirty-three non-ADHD adults diagnosed with Axis I mood or anxiety disorders comprised an "Other Psychiatric" group. Rates of comorbid disorders, including substance abuse, in the ADHD groups were typical of those reported in the adult ADHD literature. Data on the Brown ADD Scale and on the CPT were available for subsets of 61 and 46 participants, respectively. Analyses showed that the ADHD-CB, ADHD-IA, and Other Psychiatric groups all received mean scores in the clinical range on the Brown ADD Scale, with a trend toward even higher elevations in the two ADHD groups. Among 12 CPT variables assessed for the three groups, the mean scores on only two variables for the ADHD-IA group were clinically elevated. Neither the Brown ADD Scale nor CPT scores evinced sufficient sensitivity and specificity to qualify them to assist in differential diagnosis of ADHD vis-a-vis other, predominantly internalizing, psychiatric disorders.

CONCLUSION

The results indicate a need for closer examination of executive and adaptive functioning in adults with ADHD compared with those with internalizing disorders in order to identify features that could assist in differential diagnosis.

Detection of traumatic brain injury with magnetic resonance imaging and S-100B protein in children, despite normal computed tomography of the brain

OBJECTIVE

The objective of this study was to obtain data to further define the extent of traumatic brain injury by using S-100B protein and standard noncontrast magnetic resonance imaging with added fluid-attenuated inversion recovery (FLAIR) and gradient echo sequence in children with normal head computed tomography.

DESIGN

Pilot, single cohort, prospective, clinical diagnostic study.

SETTING

Pediatric intensive care and intermediate care unit in a tertiary care children's hospital.

PATIENTS

Children ages 5-18 yrs who sustained traumatic brain injury, had a negative computed tomography of the brain, and were admitted to hospital were eligible for enrollment.

INTERVENTIONS

Two blood samples were drawn for S-100B protein analysis: the first (t-1) as soon as possible or close to 6 hrs of injury and the second (t-2) close to 12 hrs from the time of injury. A magnetic resonance image of the brain was obtained within 96 hrs of injury.

MEASUREMENTS AND MAIN RESULTS

Seven of 17 patients (41%) had positive magnetic resonance image. Of the seven patients with positive magnetic resonance image, 100% (seven of seven) had a positive magnetic resonance image with FLAIR sequence, 85% (six of seven) with axial T2 sequence and 50% (three of six) with gradient echo sequence. There was no statistically significant difference in S-100B protein concentrations in patients with a positive magnetic resonance image (n = 7) and those with a negative magnetic resonance image (n = 10; p =.40 at t-1 and p =.13 at t-2). The concentration of S-100B protein was statistically significantly higher in patients with head and other bodily injury (n = 9) compared with isolated head injury (n = 6; p =.018 at t-1 and p =.025 at t-2). Patients with a positive magnetic resonance image had a lower Glasgow Coma Scale score and longer duration of hospital stay.

CONCLUSIONS

Magnetic resonance imaging seems to be a useful modality to better define the spectrum of brain injury in children with mild head trauma. The addition of S-100B protein measurement does not seem to be useful in this setting.

Catecholamine functioning in children with traumatic brain injuries and children with attention-deficit/hyperactivity disorder

Recent studies suggest that children with attention-deficit/hyperactivity disorder (ADHD) and children with traumatic brain injuries (TBI) show changes in similar neuronal networks, including the dopaminergic (DA) and norepinephrinergic (NA) systems. Therefore, indirect measures of catecholamine activity were assessed. Twenty-six children with TBI, 31 children with ADHD, and 26 normal controls, 8 to 12 years of age, were investigated with a 90-min cognitive test battery. Before and after the tests, urine samples were collected to measure catecholamine activity in response to cognitive stress. Spontaneous eyeblinking as an indirect measure of DA activity was counted. Children with TBI and ADHD excreted significantly more normetanephrine in resting situations and less epinephrine (EPI) after cognitive stress, and showed a decreased blink rate compared to normal controls. Children with TBI also showed a higher excretion of metanephrine in the resting situation in comparison to children with ADHD and controls. Whereas children with ADHD showed a higher tonic activity of the NA system and a less adaptive EPI excretion in response to cognitive stress, children with TBI seem to be additionally impaired in their tonic EPI excretion. Our study provides further support for similar but also different neurobiochemical characteristics in both groups.

Trajectories of cognitive recovery following a minor brain injury

Minor brain injury (MBI) is the most frequently diagnosed head trauma in the United States, with treatment costing more than $1.5 billion annually and many patients incapacitated for months following injury. The purpose of this study was to characterize the brain function disruptions associated with MBI and to determine the time trajectory of recovery, using a theoretical model of attention. Distractibility, impulsivity, irritability, and impaired executive functioning were demonstrated in all participants during the 24 hr after injury. Twenty percent of participants continued to complain of distractibility, impulsivity, and/or irritability throughout the 30-day study. Loss of consciousness was shown to confound participants' healing trajectories. These results suggest that standard emergency room treatment following MBI is inadequate and should include discharge directives to reduce cognitive demands for at least 48 hr at a minimum, for 30 days or longer for those with loss of consciousness.

Experienced emotion and affect recognition in adult attention-deficit hyperactivity disorder

Emotional competence and deficits that may disrupt interpersonal interactions were evaluated in 28 adults with attention-deficit hyperactivity disorder (ADHD) and 28 demographically equivalent controls. Participants completed tasks assessing affect recognition and experienced emotional intensity. Adults with ADHD performed worse in affect recognition than did adults without the disorder; however, the impairment was unrelated to gross perceptual processes, fundamental abilities in facial recognition, or attentional aspects of affect perception. Moreover, intensity of experienced emotion moderated affect recognition: Among controls, experienced emotion facilitated affect recognition. Among adults with ADHD, who reported significantly greater intensity, experienced emotion was inversely related to affect recognition. Results are consistent with theories of ADHD as a deficit in behavioral inhibition; yet, results may merely reflect a constellation of deficits associated with the disorder.

Continuous performance tests are sensitive to ADHD in adults but lack specificity. A review and critique for differential diagnosis

Historically, the focus for Attention Deficit Hyperactivity Disorder (ADHD) has been on children, with considerable research and many opinions available in this area. More recently, the focus has been expanded to include ADHD in adults. Assessment of ADHD in adults is complicated by the high rate of co-occurring disorders as well as symptom overlap with a number of disorders. One popular family of measures for the assessment of attention and executive control is the continuous performance test (CPT). A review of the available research on CPTs reveals that they are quite sensitive to CNS dysfunction. This is both a strength and a limitation of CPTs in that multiple disorders can result in impaired performance on a CPT. The high sensitivity of CPTs is further complicated by the multiple variations of CPTs available, some of which may be more sensitive or demonstrate better specificity to ADHD in adults than others. If CPTs are to be used clinically, further research will be needed to answer the questions raised by this review.

Ultrastructural and functional characteristics of blast injury-induced neurotrauma

OBJECTIVE

The present study investigates whether whole-body or local (chest) exposure to blast overpressure can induce ultrastructural, biochemical, and cognitive impairments in the brain.

METHODS

Male Wistar rats were trained for an active avoidance task for 6 days. On day 6, rats that had acquired the avoidance response were subjected to whole-body blast injury (WBBI), generated by large-scale shock tube (n = 40); or local (chest) blast injury (LBI), induced by blast overpressure focused on the right middle thoracic region and generated by small-scale shock tube (n = 40) while the heads of animals were protected. At the completion of cognitive testing, rats were killed at 3 hours, 24 hours, and 5 days after injury. Ultrastructural changes in the hippocampus were analyzed electron microscopically. Parameters of oxidative stress (malondialdehyde and superoxide anion generation) and antioxidant enzyme defense (superoxide dismutase and glutathione peroxidase activity) were measured in the hippocampus to assess biochemical changes in the brain after blast.

RESULTS

Ultrastructural findings in animals subjected to WBBI or LBI demonstrated swellings of neurons, glial reaction, and myelin debris in the hippocampus. All rats revealed significant deficits in performance of the active avoidance task 3 hours after injury, but deficits persisted up to day 5 after injury only in rats subjected to WBBI. Oxidative stress development and altered antioxidant enzyme defense was observed in animals in both groups. Cognitive impairment and biochemical changes in the hippocampus were significantly correlated with blast injury severity in both WBBI and LBI groups.

CONCLUSION

These results confirm that exposure to blast overpressure induces ultrastructural and biochemical impairments in the brain hippocampus, with associated development of cognitive deficits.

Impaired motor learning and diffuse axonal damage in motor and visual systems of the rat following traumatic brain injury

Cognitive-motor functioning or motor skill learning is impaired in humans following traumatic brain injury. A more complete understanding of the mechanisms involved in disorders of motor skill learning is essential for any effective rehabilitation. The specific goals of this study were to examine motor learning disorders, and their relationship to pathological changes in adult rats with mild to moderate closed head injury. Motor learning deficits were determined by comparing the ability to complete a series of complex motor learning tasks with simple motor activity. The extent of neuronal damage was determined using silver impregnation. At all post-injury time points (day 1 to day 14), statistically significant deficits were observed in parallel bar traversing, foot placing, ladder climbing, and rope climbing. Performance improved with time, but never reached control levels. In contrast, no deficits were found in simple motor activity skills tested with beam balance and runway traverse. Histologically, axonal degeneration was widely distributed in several brain areas that relate to motor learning, including the white matter of sensorimotor cortex, corpus callosum, striatum, thalamus and cerebellum. Additionally, severely damaged axons were observed in the primary visual pathway, including the optic chiasm, optic tract, lateral geniculate nuclei, and superior colliculus. These findings suggest that motor learning deficits could be detected in mild or moderate brain injury, and this deficit could be attributed to a diffuse axonal injury distributed both in the motor and the visual systems.

The postconcussion syndrome after mild head trauma part II: is migraine underdiagnosed?

The evidence for post-traumatic migraine as the cause of the postconcussion syndrome in a proportion of patients is reviewed.

CONCLUSION

patients suffering recurrent post-traumatic headaches or other elements of the postconcussion syndrome should be treated for migraine.

Inhibitory control in children with traumatic brain injury (TBI) and children with attention deficit/hyperactivity disorder (ADHD)

The behavioural and cognitive sequelae of traumatic brain injury (TBI) have features in common with attention deficit/hyperactivity disorder (ADHD), best characterized by deficits in response inhibition.The performance was, therefore, examined of 27 children with TBI, 31 children with developmental ADHD, and 26 matched controls aged 8-12, on two inhibition tasks: the Stop-Signal Task and a Delayed-Response-Task. Children with TBI and children with ADHD showed a pervasive deficit in their inhibitory control processes with respect to inhibition of both pre-potent and on-going responses. In addition, children with TBI were found to suffer from a general slowing of their information processing, which was not correlated with the inhibition deficit. TBI children with and without a secondary ADHD differed only tendentially in their Mean Go-Reaction time in the stop-task. However, subdividing TBI children according to actigraph data into hypo-, hyper- and normokinetic subgroups revealed that the hyperactive TBI children had inhibitory deficit patterns that were similar to children with developmental ADHD. It is concluded that slowing of information processing speed seems to be a general consequence of TBI in childhood, whereas slowing of the stop-processes or inhibitory deficits, specifically, are associated with post-injury hypo- or hyperactivity.

Traumatic brain damage in minor head injury: relation of serum S-100 protein measurements to magnetic resonance imaging and neurobehavioral outcome

OBJECTIVE

The present study was conducted to validate S-100 protein as a marker of brain damage after minor head injury.

METHODS

We studied 50 patients with minor head injuries and Glasgow Coma Scale scores of 13 to 15 in whom computed tomographic scans of the brain revealed no abnormalities. Serum levels of S-100 protein were measured at admittance and hourly thereafter until 12 hours after injury. Magnetic resonance imaging and baseline neuropsychological examinations were performed within 48 hours, and neuropsychological follow-up was conducted at 3 months postinjury.

RESULTS

Fourteen patients (28%) had detectable serum levels of S-100 protein (mean peak value, 0.4 microg/L [standard deviation, +/- 0.3]). The S-100 protein levels were highest immediately after the trauma, and they declined each hour thereafter. At 6 hours postinjury, the serum level was below the detection limit (0.2 microg/L) in five (36%) of the patients with initially detectable levels. Magnetic resonance imaging revealed brain contusions in five patients, four of whom demonstrated detectable levels of S-100 protein in serum. The proportion of patients with detectable serum levels was significantly higher when magnetic resonance imaging revealed a brain contusion. In patients with detectable serum levels, we observed a trend toward impaired neuropsychological functioning on measures of attention, memory, and information processing speed.

CONCLUSION

Determination of S-100 protein levels in serum provides a valid measure of the presence and severity of traumatic brain damage if performed within the first hours after minor head injury.

Recovery from mild head injury

The subjective and objective sequelae accompanying mild head injury (MHI) are discussed in an attempt to clarify MHI's immediate and long-term consequences. Areas covered included epidemiology, classification, the post-concussive syndrome (PCS), malingering, extent of recovery, rehabilitation and guidelines for clinical practice. Special emphasis is placed on the poor relationship between subjective complaint and objective measures of impairment. Also discussed are some of the methodological problems in the MHI literature, including attempts to match MHI subjects and controls with respect to cognitive and emotional complaint and the possible confounding effects of practice. The evidence for long-lasting (i.e. more than 1 year), subtle neurobehavioral impairment after MHI indicates that additional research is required on MHI 1 year or more after injury.

Motor performance following a mild traumatic brain injury in children: an exploratory study

Mild Traumatic Brain Injury (TBI) is a common occurrence in the paediatric population and, as the concept of motor performance has not been assessed specifically in this population, the purpose of this study was to determine if motor performance deficits are present and can be objectively identified in a sample of children having sustained a mild TBI (Glasgow Coma Scale score 13-15). Twenty-eight children aged between 5 and 15 years were recruited immediately post-trauma. Subjects were considered normal on standard neurological exam at the time of discharge. They were assessed 13-18 days post-trauma using the Bruininks-Oseretsky Test of Motor Proficiency, a norm referenced clinical standardized assessment tool. Compared to published norms, motor performance was significantly lower in domains of balance, response speed and running speed an agility (t-test p < 0.01), and significantly higher in domains of upper extremity coordination and visual motor control (t-test p < 0.01). Although excellent performance can be observed in domains requiring upper limb coordination, motor planning and execution of motor tasks, deficits in balance and response speed can be identified in a significant number of children even after mild TBI. More specific and sensitive evaluations are necessary to identify the exact nature of the problems and evaluate their functional impact on daily activities.

Reaction and movement time variability in ADD/H: effect of tactile experience

A clinical group of children with attention deficit disorders with hyperactivity (ADD/H) was compared to a control group, each divided into high and low variability (HV and LV) on reaction time (RT) and movement time (MT) measures. The effects of tactile-somatosensory experience on performance was also investigated. Analyses of the HV and LV groups based on RT variability found improvement on MT in both HV groups (ADD/H and control) following a tactile-somatosensory task. Both HV groups based on MT variability also showed improvement in MT following the TPT administration. No LV group (based on either RT or MT) showed improvement in MT or RT. The results in this study indicated that HV (either RT or MT) predicted improved speed and accuracy following a tactile somatosensory task. Several neuroanatomical models for the study of response variability and the role of tactile somatosensory training programmes in paediatric rehabilitation are discussed.

Alternate finger tapping test in patients with migraine

Migraine patients are thought to show some cognitive dysfunction and slight structural abnormalities in the white matter of the brain, whereas most patients with multiple sclerosis (MS) are known to have numerous white matter lesions, often affecting the corpus callosum. To demonstrate psychomotor dysfunction, an alternate finger tapping task (a-FTT) on a PC was administered to controls (n = 41), migraine patients (n = 25), and multiple sclerosis patients (n = 22). Five MS patients with secondary callosal atrophy detected by MRI were also investigated as a separate group. Significant slowing was demonstrated in migraine (P = 0.0005) and MS (P<0.0001). The poorest test results were found in patients with callosal atrophy. In summary, a-FTT on a PC is able to detect minimal psychomotor dysfunction in migraine.