Response inhibition in children with and without ADHD after traumatic brain injury

Fifty years of executive control research in attention-deficit/hyperactivity disorder:What we have learned and still need to know

For 50 years, attention-deficit/hyperactivity disorder (ADHD) has been considered a disorder of executive control (EC), the higher-order, cognitive skills that support self-regulation, goal attainment and what we generally call "attention." This review surveys our current understanding of the nature of EC as it pertains to ADHD and considers the evidence in support of eight hypotheses that can be derived from the EC theory of ADHD. This paper provides a resource for practitioners to aid in clinical decision-making. To support theory building, I draw a parallel between the EC theory of ADHD and the common gene-common variant model of complex traits such as ADHD. The conclusion offers strategies for advancing collaborative research.

A Systematic Scoping Review of New Attention Problems Following Traumatic Brain Injury in Children

Objective: To summarize existing knowledge about the characteristics of attention problems secondary to traumatic brain injuries (TBI) of all severities in children.

Methods: Computerized databases PubMed and PsychINFO and gray literature sources were used to identify relevant studies. Search terms were selected to identify original research examining new ADHD diagnosis or attention problems after TBI in children. Studies were included if they investigated any severity of TBI, assessed attention or ADHD after brain injury, investigated children as a primary or sub-analysis, and controlled for or excluded participants with preinjury ADHD or attention problems.

Results: Thirty-nine studies were included in the review. Studies examined the prevalence of and risk factors for new attention problems and ADHD following TBI in children as well as behavioral and neuropsychological factors associated with these attention problems. Studies report a wide range of prevalence rates of new ADHD diagnosis or attention problems after TBI. Evidence indicates that more severe injury, injury in early childhood, or preinjury adaptive functioning problems, increases the risk for new ADHD and attention problems after TBI and both sexes appear to be equally vulnerable. Further, literature suggests that cases of new ADHD often co-occurs with neuropsychiatric impairment in other domains. Identified gaps in our understanding of new attention problems and ADHD include if mild TBI, the most common type of injury, increases risk and what brain abnormalities are associated with the emergence of these problems.

Conclusion: This scoping review describes existing studies of new attention problems and ADHD following TBI in children and highlights important risk factors and comorbidities. Important future research directions are identified that will inform the extent of this outcome across TBI severities, its neural basis and points of intervention to minimize its impact.

Detecting mental health problems after paediatric acquired brain injury: A pilot Rasch analysis of the strengths and difficulties questionnaire

The parent-reported Strengths and Difficulties Questionnaire (SDQ-P) is commonly used to assess for mental health problems, but its psychometric properties have not been studied in the paediatric Acquired Brain Injury (ABI) population. This study investigated the properties of the SDQ-P and its subscales in this population using Rasch analysis. One hundred and forty-three SDQ-Ps and 123 Impact Supplements were analyzed. Sixty-nine percent of SDQ-Ps were completed by female carers, 59% of young people were male, and 58% had Traumatic Brain Injury (TBI). In this population the SDQ-P Total Difficulties Scale and the Conduct Problems subscale showed questionable construct validity. The individual subscales and Impact Supplement did not meet the criteria for reliability. Two items had disordered thresholds. The individual subscales showed mistargeting and 13-24% person misfit. Two items were significantly underdiscriminating. There was differential item functioning with age and time post-injury, and local dependence between subscale items. The Total Difficulties scale was multidimensional. The most easily endorsed items were in keeping with common symptoms of brain injury. These findings suggest the SDQ-P in its current form may not be a reliable and valid assessment measure for mental health difficulties in the paediatric ABI population and requires further investigation.

Subtle Motor Signs and Executive Functioning in Chronic Paediatric Traumatic Brain Injury: Brief Report

Background: Children with traumatic brain injury (TBI) are reported to have persistent deficits in executive functioning and subtle motor functionsAim: This study examined the relationship between subtle motor signs and executive functioning in children with TBIMethods: Eighteen children aged 13-18 years with mild to severe TBI at least one year before study participation and 16 age-matched typically-developing controls were examined using the Revised Physical and Neurological Examination of Subtle Signs (PANESS), a simplified Go/No-go task, portions of the Delis-Kaplan Executive Function System Verbal Fluency and Trail Making tests, and a Wechsler Coding testResults: There were significant associations between PANESS scores and executive functioning measures in children with TBI but not in controls. Conclusion: Results suggest that assessment of subtle motor signs may provide broader information regarding functioning after pediatric TBI.

Preliminary findings of altered functional connectivity of the default mode network linked to functional outcomes one year after pediatric traumatic brain injury

PURPOSE AND METHOD

This study examined functional connectivity of the default mode network (DMN) and examined brain-behavior relationships in a pilot cohort of children with chronic mild to moderate traumatic brain injury (TBI).

RESULTS

Compared to uninjured peers, children with TBI demonstrated less anti-correlated functional connectivity between DMN and right Brodmann Area 40 (BA 40). In children with TBI, more anomalous less anti-correlated) connectivity between DMN and right BA 40 was linked to poorer performance on response inhibition tasks.

CONCLUSION

Collectively, these preliminary findings suggest that functional connectivity between DMN and BA 40 may relate to longterm functional outcomes in chronic pediatric TBI.

Response Inhibition Deficits and Altered Motor Network Connectivity in the Chronic Phase of Pediatric Traumatic Brain Injury

Poor response inhibition is a hallmark of pediatric traumatic brain injury (TBI). We assessed motor response inhibition by measuring commission error rates on Simple (minimized cognitive demands) and Motivation (monetary reward) Go/No-Go tasks, comparing 17 children with chronic TBI (>1 year post-injury) and 14 matched, uninjured peers. Using resting state functional magnetic resonance imaging (fMRI), we examined between-group differences in whole-brain intrinsic connectivity of the motor network as derived from the averaged time course of bilateral primary motor cortex seeds, to identify regions of interest (ROIs) for brain-behavior correlations. Independent sample t tests compared Go/No-Go performance and connectivity at the ROI level. Pearson correlations examined relationships between intrinsic connectivity at the ROI level and Go/No-Go performance. Adolescents with TBI showed poorer performance on Simple and Motivation Go/No-Go tasks compared with controls. In whole-brain contrasts, adolescents with TBI showed significantly reduced functional connectivity between the motor network and voxels within the left caudate. Furthermore, in ROI analyses, the group with TBI had significantly lower connectivity between the motor network and left caudate and numerically lower connectivity between the motor network and right caudate. In adolescents with TBI, lower motor network to left caudate connectivity correlated with poorer Simple task performance; lower motor network to right caudate connectivity correlated with poorer Simple and Motivation task performance. No significant brain-behavior relationships existed among controls. These results are consistent with previous pediatric TBI literature and suggest that disrupted intrinsic connectivity of a corticostriatal motor network may contribute to response inhibition deficits.

Brain structure, working memory and response inhibition in childhood leukemia survivors

INTRODUCTION

Survival rates for children with acute lymphoblastic leukemia (ALL) approach 95%. At the same time, there is growing concern that chemotherapy causes alterations in brain development and cognitive abilities. We performed MRI measurements of white and gray matter volume to explore how variation in brain structure may be related to cognitive abilities in ALL survivors and healthy controls.

METHODS

The sample included 24 male ALL survivors who had completed contemporary treatment 3-11 years prior, and 21 age- and sex-matched controls. Participants were between 8 and 18 years old. Working memory and motor response inhibition were measured with the N-Back and Stop Signal Tasks (SST), respectively. Participants underwent 3T structural MRI to assess white and gray matter volumes overall, lobe-wise, and in cortical and atlas-identified subcortical structures. Mental health was assessed with the Child Behavioral Checklist.

RESULTS

ALL survivors performed more poorly on measures of working memory and response inhibition than controls. Frontal and parietal white matter, temporal and occipital gray matter volume, and volumes of subcortical white and gray matter structures were significantly reduced in ALL survivors compared with controls. Significant structure-function correlations were observed between working memory performance and volume of the amygdala, thalamus, striatum, and corpus callosum. Response inhibition was correlated with frontal white matter volume. No differences were found in psychopathology.

CONCLUSIONS

Compared with controls, a reduction in volume across brain regions and tissue types, was detectable in ALL survivors years after completion of therapy. These structural alterations were correlated with neurocognitive performance, particularly in working memory. Confirming these observations in a larger, more representative sample of the population is necessary. Additionally, establishing the time course of these changes-and the treatment, genetic, and environmental factors that influence them-may provide opportunities to identify at-risk patients, inform the design of treatment modifications, and minimize adverse cognitive outcomes.

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.

The association between traumatic brain injury and ADHD in a Canadian adult sample

OBJECTIVE

This study describes the association between lifetime traumatic brain injury (TBI) and attention deficit and hyperactivity disorder (ADHD) among Canadian adults.

METHOD

A cross-sectional sample of 3993 Ontario adults aged 18 or older were surveyed by Computer Assisted Telephone Interviewing (CATI) throughout 2011 and 2012 as part of the CAMH Monitor, a rolling survey assessing the health, mental health and substance use of Ontario adults. TBI was defined as trauma to the head that resulted in loss of consciousness for at least five minutes or overnight hospitalization. ADHD was measured by the 6-item ASRS screener for adult ADHD, and self-reported history of diagnosed ADHD.

RESULTS

Among adults with a history of TBI, 6.6% (95% CI: 4.7, 9.4) screened ADHD positive, and 5.9% (95% CI: 3.6, 9.5) reported having been diagnosed with ADHD in their lifetime. Adults with lifetime TBI had significantly greater odds of scoring positive on the ADHD/ASRS screen (OR = 2.49, 95% CI: 1.54, 4.04), and of reporting a history of diagnosed ADHD (OR = 2.64, 95% CI: 1.40, 4.98) than without TBI, when holding values of sex, age, and education constant.

CONCLUSION

Significant positive associations between lifetime TBI and both current and past ADHD were observed among adults in this population. More research to understand these associations, and their significance for the etiology and management of TBI and ADHD, is needed.

Neuropsychological performance of youth with secondary attention-deficit/hyperactivity disorder 6- and 12-months after traumatic brain injury

The present study compared executive dysfunction among children with attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (S-ADHD), pre-injury ADHD and children with TBI only (i.e., no ADHD). Youth aged 6-16 years admitted for TBI to five trauma centers were enrolled (n=177) and evaluated with a semi-structured psychiatric interview scheduled on three occasions (within 2 weeks of TBI, i.e., baseline assessment for pre-injury status; 6-months and 12-months post-TBI). This permitted the determination of 6- and 12-month post-injury classifications of membership in three mutually exclusive groups (S-ADHD; pre-injury ADHD; TBI-only). Several executive control measures were administered. Unremitted S-ADHD was present in 17/141 (12%) children at the 6-month assessment, and in 14/125 (11%) children at 12-months post-injury. The study found that children with S-ADHD exhibited deficient working memory, attention, and psychomotor speed as compared to children with pre-injury ADHD. Furthermore, the children with S-ADHD and the children with TBI-only were impaired compared to the children with pre-injury ADHD with regard to planning. No group differences related to response inhibition emerged. Age, but not injury severity, gender, or adaptive functioning was related to executive function outcome. Neuropsychological sequelae distinguish among children who develop S-ADHD following TBI and those with TBI only. Moreover, there appears to be a different pattern of executive control performance in those who develop S-ADHD than in children with pre-injury ADHD suggesting that differences exist in the underlying neural mechanisms that define each disorder, underscoring the need to identify targeted treatment interventions.

Neuropsychiatry of pediatric traumatic brain injury

Pediatric traumatic brain injury (TBI) is a major public health problem. Psychiatric disorders with onset before the injury are more common than population base rates. Novel (postinjury onset) psychiatric disorders (NPD) are also common and complicate child function after injury. Novel disorders include personality change due to TBI, secondary attention-deficit/hyperactivity disorder, other disruptive behavior disorders, and internalizing disorders. This article reviews preinjury psychiatric disorders as well as biopsychosocial risk factors and treatments for NPD.