White matter microstructure abnormalities and executive function in adolescents with prenatal cocaine exposure

DTI of Opioid-Exposed Fetuses Using ComBat Harmonization: A Bi-Institutional Study

BACKGROUND AND PURPOSE

The underlying mechanisms leading to altered cognitive, behavioral, and vision outcomes in children with prenatal opioid exposure are yet to be fully understood. Some studies suggest WM alterations in infants and children with prenatal opioid exposure; however, the time course of WM changes is unknown. We aimed to evaluate differences in diffusion tensor imaging MRI parameters in the brain between opioid exposed fetuses and normal controls.

MATERIALS AND METHODS

This is a pilot, prospective cohort study in which subjects in the third trimester of pregnancy underwent fetal DTI of the brain with 20 noncolinear diffusion directions and a b-value of 500 s/mm2 at 2.5-mm isotropic resolution.

RESULTS

The study included a total of 26 fetuses, 11 opioid-exposed (mean gestational age, 32.61 [SD, 2.35] weeks) and 15 unexposed controls (mean gestational age, 31.77 [SD, 1.68] weeks). After we adjusted for gestational age, fractional anisotropy values were significantly higher in opioid-exposed fetuses relative to controls in 8 WM tracts: the bilateral lemniscus (left: P = .017; right: P = .020), middle cerebellar peduncle (P = .027), left inferior cerebellar peduncle (P = .026), right sagittal stratum (P = .040), right fornix stria terminalis (P = .022), right inferior fronto-occipital fasciculus (P = .011), and the right uncinate fasciculus (P = .033). Significant alteration was also identified in other DTI indices involving a series of brain regions.

CONCLUSIONS

Our data demonstrate initial evidence of cerebral WM microstructural differences between opioid-exposed fetuses and unexposed controls. Further studies in larger patient populations will be needed to fully understand these findings.

Strengthened and posterior-shifted structural rich-club organization in people who use cocaine

BACKGROUND

People with cocaine use disorder (CUD) often have abnormal cognitive function and brain structure. Cognition is supported by brain networks that typically have characteristics like rich-club organization, which is a group of regions that are highly connected across the brain and to each other, and small worldness, which is a balance between local and long-distance connections. However, it is unknown whether there are abnormalities in structural brain network connectivity of CUD.

METHODS

Using diffusion-weighted imaging, we measured structural connectivity in 37 people with CUD and 38 age-matched controls. We identified differences in rich-club organization and whether such differences related to small worldness and behavior. We also tested whether rich-club reorganization was associated with caudate and putamen structural connectivity due to the relevance of the dopamine system to cocaine use.

RESULTS

People with CUD had a higher normalized rich-club coefficient than controls, more edges connecting rich-club nodes to each other and to non-rich-club nodes, and fewer edges connecting non-rich-club nodes. Rich-club nodes were shifted posterior and lateral. Rich-club reorganization was related to lower clustered connectivity around individual nodes found in CUD, to increased impulsivity, and to a decrease in caudate connectivity.

CONCLUSIONS

These findings are consistent with previous work showing increased rich-club connectivity in conditions associated with a hypofunctional dopamine system. The posterior shift in rich-club nodes in CUD suggests that the structural connectivity of posterior regions may be more impacted than previously recognized in models based on brain function and morphology.

The impact of levamisole and alcohol on white matter microstructure in adult chronic cocaine users

Previous brain imaging studies with chronic cocaine users (CU) using diffusion tensor imaging (DTI) mostly focused on fractional anisotropy to investigate white matter (WM) integrity. However, a quantitative interpretation of fractional anisotropy (FA) alterations is often impeded by the inherent limitations of the underlying tensor model. A more fine-grained measure of WM alterations could be achieved by measuring fibre density (FD). This study investigates this novel DTI metric comparing 23 chronic CU and 32 healthy subjects. Quantitative hair analysis was used to determine intensity of cocaine and levamisole exposure-a cocaine adulterant with putative WM neurotoxicity. We first assessed the impact of cocaine use, levamisole exposure and alcohol use on group differences in WM integrity. Compared with healthy controls, all models revealed cortical reductions of FA and FD in CU. At the within-patient group level, we found that alcohol use and levamisole exposure exhibited regionally different FA and FD alterations than cocaine use. We found mostly negative correlations of tract-based WM associated with levamisole and weekly alcohol use. Specifically, levamisole exposure was linked with stronger WM reductions in the corpus callosum than alcohol use. Cocaine use duration correlated negatively with FA and FD in some regions. Yet, most of these correlations did not survive a correction for multiple testing. Our results suggest that chronic cocaine use, levamisole exposure and alcohol use were all linked to significant WM impairments in CU. We conclude that FD could be a sensitive marker to detect the impact of the use of multiple substances on WM integrity in cocaine but also other substance use disorders.

Prenatal drug exposure and executive function in early adolescence

PURPOSE

Study of the relationship between prenatal cocaine exposure (PCE) and executive function (EF) has yielded inconsistent results. The purpose of the current study is to examine whether PCE, biological sex, environmental risk, and their interaction predicted EF in early adolescence.

METHODS

135 12-year-old adolescents (40.7% with PCE), who were followed prospectively from birth, attempted up to 8 Tower of Hanoi (ToH) puzzle trials of increasing complexity. The number of correctly completed puzzles served as the main outcome measure. Survival analysis was used to examine predictors of the number of successfully completed trials.

RESULTS

As trial difficulty increased, fewer adolescents were able to solve the TOH puzzle. Adolescents from high risk environments and with either prenatal alcohol or prenatal cannabis exposure completed fewer puzzles (p < .05). In addition, a hypothesized 3-way interaction of PCE x sex x environmental risk was found such that cocaine-exposed males with high environmental risk had the worst performance (p < .01).

CONCLUSIONS

The current findings are consistent with prior research indicating that males with PCE may be at particular risk of poorer functioning and highlight the potential importance of examining adolescent's sex and environmental risk as moderators of PCE effects.

Neuroimaging in infants with prenatal opioid exposure: Current evidence, recent developments and targets for future research

Prenatal opioid exposure (POE) has shown to be a risk factor for adverse long-term cognitive and behavioral outcomes in offspring. However, the neural mechanisms of these outcomes remain poorly understood. While preclinical and human studies suggest that these outcomes may be due to opioid-mediated changes in the fetal and early postnatal brain, other maternal, social, and environmental factors are also shown to play a role. Recent neuroimaging studies reveal brain alterations in children with POE. Early neuroimaging and novel methodology could provide an in vivo mechanistic understanding of opioid mediated alterations in developing brain. However, this is an area of ongoing research. In this review we explore recent imaging developments in POE, with emphasis on the neonatal and infant brain, and highlight some of the challenges of imaging the developing brain in this population. We also highlight evidence from animal models and imaging in older children and youth to understand areas where future research may be targeted in infants with POE.

Sex Differences in the Association between Household Income and Children's Executive Function

The study aimed to investigate sex differences in the boosting effects of household income on children's executive function in the US. This is a cross-sectional study using data from Wave 1 of the Adolescent Brain Cognitive Development (ABCD) study. Wave 1 ABCD included 8608 American children between ages 9 and 10 years old. The independent variable was household income. The primary outcome was executive function measured by the stop-signal task. Overall, high household income was associated with higher levels of executive function in the children. Sex showed a statistically significant interaction with household income on children's executive function, indicating a stronger effect of high household income for female compared to male children. Household income is a more salient determinant of executive function for female compared to male American children. Low-income female children remain at the highest risk regarding poor executive function.

Behavioral development in children with prenatal substance exposure and neonatal abstinence syndrome: Associated factors and implications

PROBLEM

Prenatal substance exposure and neonatal abstinence syndrome (NAS) are risk factors for adverse behavioral outcomes in children at 24 months of age.

METHODS

The purpose of this study was to examine factors associated with abnormal behavioral development in children with prenatal substance exposure or NAS through 10 years of age. A retrospective, nonexperimental, longitudinal design to examine the effects of prenatal substance exposure and NAS on behavioral development at 1, 5, and 10 years of age, while controlling for intrapersonal, interpersonal, community, organizational, and public policy characteristics. A hierarchical multivariate logistic regression model was used to evaluate the influence of substance exposure and NAS on behavioral outcomes.

FINDINGS

Abnormal behavioral development was predicted at 10 years of age with polysubstance exposure to three substances (odds ratio [OR] = 2.711, p < 0.01) and NAS (OR = 2.077, p < .001).

CONCLUSION

Psychiatric nursing care for children with prenatal substance exposure and NAS should include implementation of early and continued behavioral evaluation and childhood trauma and adversity surveillance in children through middle childhood.

What proportion of the brain structural and functional abnormalities observed among children with fetal alcohol spectrum disorder is explained by their prenatal alcohol exposure and their other prenatal and postnatal risks?

BACKGROUND

Individuals with prenatal alcohol exposure (PAE) often present with a myriad of other prenatal (e.g. exposure to tobacco and other illicit drugs, poor prenatal care) and postnatal risk factors (e.g. multiple home placements, physical/sexual abuse, low socio-economic status)-all of which are likely contributing to their adverse outcomes.

METHODS

A comprehensive neuropsychological battery, coupled with magnetic resonance imaging, was administered to children with fetal alcohol spectrum disorders (FASD) in 2009. Study participants diagnosed with FASD by the University of Washington using the FASD 4-Digit Code were compared to typically-developing peers with no PAE. Data from this MRI study were used to explore the proportion of variance in brain structural and functional abnormalities explained by PAE and 14 other prenatal and postnatal risk factors.

RESULTS

PAE was the dominant risk factor explaining the largest proportion of variance in regional brain size (total brain, frontal lobe, caudate, hippocampus and corpus callosum) and brain function (intellect, achievement, memory, language, executive-function, motor, adaptation, behavior-attention and mental health symptoms). Other prenatal and postnatal risk factors were 3 to 7-fold more prevalent than in the general population. Individually, each risk factor explained a statistically significant, but smaller proportion of variance in brain outcome compared to PAE. In combination, the proportion of variance explained by the presence of multiple prenatal and postnatal risks rivaled that of PAE.

CONCLUSION

A better understanding of the impact other prenatal and postnatal risk factors have on the neurodevelopmental outcomes of individuals with FASD can inform more effective prevention and intervention strategies.

Characterizing adverse prenatal and postnatal experiences in children

BACKGROUND

Prenatal and postnatal adversities, including prenatal alcohol exposure (PAE), prenatal exposure to other substances, toxic stress, lack of adequate resources, and postnatal abuse or neglect, often co-occur. These exposures can have cumulative effects, or interact with each other, leading to worse outcomes than single exposures. However, given their complexity and heterogeneity, exposures can be difficult to characterize. Clinical services and research often overlook additional exposures and attribute outcomes solely to one factor.

METHODS

We propose a framework for characterizing adverse prenatal and postnatal exposures and apply it to a cohort of 77 children. Our approach considers type, timing, and frequency to quantify PAE, other prenatal substance exposure, prenatal toxic stress, postnatal threat (harm or threat of harm), and postnatal deprivation (failure to meet basic needs) using a 4-point Likert-type scale. Postnatal deprivation and harm were separated into early (<24 months of age) and late (≥24 months) time periods, giving seven exposure variables. Exposures were ascertained via health records, child welfare records, interviews with birth parents, caregivers, and/or close family/friends.

RESULTS

Nearly all children had co-occurring prenatal exposures, and two-thirds had both prenatal and postnatal adversities. Children with high PAE were more likely to experience late postnatal adversities, and children with other prenatal substance exposure were more likely to have early postnatal deprivation. Postnatal adversities were more likely to co-occur.

CONCLUSION

This framework provides a comprehensive picture of a child's adverse exposures, which can inform assessment and intervention approaches and policy and will be useful for future research.

Stroop Color-Word Interference Test: Normative data for Spanish-speaking pediatric population

OBJECTIVE

To generate normative data for the Stroop Word-Color Interference test in Spanish-speaking pediatric populations.

METHOD

The sample consisted of 4,373 healthy children from nine countries in Latin America (Chile, Cuba, Ecuador, Guatemala, Honduras, Mexico, Paraguay, Peru, and Puerto Rico) and Spain. Each participant was administered the Stroop Word-Color Interference test as part of a larger neuropsychological battery. The Stroop Word, Stroop Color, Stroop Word-Color, and Stroop Interference scores were normed using multiple linear regressions and standard deviations of residual values. Age, age2, sex, and mean level of parental education (MLPE) were included as predictors in the analyses.

RESULTS

The final multiple linear regression models showed main effects for age on all scores, except on Stroop Interference for Guatemala, such that scores increased linearly as a function of age. Age2 affected Stroop Word scores for all countries, Stroop Color scores for Ecuador, Mexico, Peru, and Spain; Stroop Word-Color scores for Ecuador, Mexico, and Paraguay; and Stroop Interference scores for Cuba, Guatemala, and Spain. MLPE affected Stroop Word scores for Chile, Mexico, and Puerto Rico; Stroop Color scores for Mexico, Puerto Rico, and Spain; Stroop Word-Color scores for Ecuador, Guatemala, Mexico, Puerto Rico and Spain; and Stroop-Interference scores for Ecuador, Mexico, and Spain. Sex affected Stroop Word scores for Spain, Stroop Color scores for Mexico, and Stroop Interference for Honduras.

CONCLUSIONS

This is the largest Spanish-speaking pediatric normative study in the world, and it will allow neuropsychologists from these countries to have a more accurate approach to interpret the Stroop Word-Color Interference test in pediatric populations.

White Matter Integrity Disruptions Correlate With Cognitive Impairments in Asthma

BACKGROUND

Cognitive impairments are common in asthma, which is a serious global health problem characterized by chronic airway inflammation. However, the underlying neuromechanism is still unclear.

PURPOSE/HYPOTHESIS

To investigate the neuromechanism underlying cognitive impairments of asthma. We hypothesized that asthma patients exhibit altered white matter (WM) microstructures, which may contribute to their cognitive impairments.

STUDY TYPE

Case-control study.

SUBJECTS

37 patients with asthma (14 male) and 31 healthy controls (10 male).

FIELD STRENGTH/SEQUENCE

Diffusion tensor imaging (DTI) covering the whole brain was acquired on a 3.0T scanner using a single-shot echo planar imaging sequence.

ASSESSMENT

A DTI with tract-based spatial statistics (TBSS) approach was used to investigate the whole-brain differences in the WM fractional anisotropy (FA) values.

STATISTICAL TESTS

Demographic and neuropsychological data were performed using two independent sample t-test or chi-square test or Mann-Whitney rank test. The relationship between cognitive impairments and WM abnormalities was studied using correlation analyses.

RESULTS

Impairments of language ability, executive function, and visual-spatial processing and widespread WM disruptions reflected by FA reduction were found in asthma patients. The executive function was related to left forceps major, cingulum, and right uncinate fasciculus, ILF (inferior longitudinal fasciculus) positively (P < 0.05). FA abnormalities were positively correlated with duration of asthma and asthma control test (ACT) scores.

DATA CONCLUSION

Asthma patients display multiple cognitive impairments and universally WM integrity disruptions, among which executive dysfunction closely correlates with WM abnormalities.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018.

Diffusion MRI of white matter microstructure development in childhood and adolescence: Methods, challenges and progress

Diffusion magnetic resonance imaging (dMRI) continues to grow in popularity as a useful neuroimaging method to study brain development, and longitudinal studies that track the same individuals over time are emerging. Over the last decade, seminal work using dMRI has provided new insights into the development of brain white matter (WM) microstructure, connections and networks throughout childhood and adolescence. This review provides an introduction to dMRI, both diffusion tensor imaging (DTI) and other dMRI models, as well as common acquisition and analysis approaches. We highlight the difficulties associated with ascribing these imaging measurements and their changes over time to specific underlying cellular and molecular events. We also discuss selected methodological challenges that are of particular relevance for studies of development, including critical choices related to image acquisition, image analysis, quality control assessment, and the within-subject and longitudinal reliability of dMRI measurements. Next, we review the exciting progress in the characterization and understanding of brain development that has resulted from dMRI studies in childhood and adolescence, including brief overviews and discussions of studies focusing on sex and individual differences. Finally, we outline future directions that will be beneficial to the field.

White-matter crossing-fiber microstructure in adolescents prenatally exposed to cocaine

BACKGROUND

Prenatal cocaine exposure (PCE) is associated with risk-taking behaviors, including increased initiation of substance use in adolescence. The neurobiological underpinnings of these behaviors in adolescents with PCE are not well understood. The goal of this study was to compare diffusion-weighted imaging data between adolescents with and without PCE using crossing-fiber models, which may provide more comprehensive estimates of white-matter microstructure within regions of multiple (e.g., primary and secondary) fiber orientations.

METHODS

Thirty-nine PCE individuals and 17 comparably aged prenatally non-drug-exposed (NDE) youths were recruited from a longitudinal cohort followed since birth. White matter was examined using tensor-derived and crossing-fiber models. Whole-brain investigations were performed, as were analyses on seven white-matter regions, which included the splenium, body and genu of the corpus callosum, bilateral cingulum, and the right and left superior longitudinal fasciculus (SLF).

RESULTS

Whole-brain analyses revealed no group differences. However, ROI analyses for anisotropy estimates derived from the crossing-fiber model revealed significant group differences for secondary fibers, with reduced anisotropy among PCE adolescents compared to prenatally non-exposed youth in the right cingulum and the left SLF, and increased anisotropy in the genu.

CONCLUSIONS

Our findings suggest that white-matter differences in PCE adolescents are subtle and localized primarily within secondary fiber orientations, perhaps arising from altered white-matter development.

Executive function in children with prenatal cocaine exposure (12-15years)

PURPOSE

Prenatal exposure to cocaine (PCE) may alter areas of the brain dense with monoamine receptors such as the prefrontal cortex and negatively affect cognitive processes implicated in executive function (EF). This study investigated the effects of PCE on EF at 12 and 15years.

METHODS

EF was examined in 189 PCE and 183 non-cocaine exposed (NCE) children who were primarily African American and of low socioeconomic status. Caregivers rated their child on the Behavior Rating Inventory of Executive Function (BRIEF) at ages 12 and 15. The BRIEF includes two summary scales and eight subscales: Behavioral Regulation Index (BRI) (Inhibit, Shift, and Emotion) and Metacognition Index (MI) (Monitor, Working Memory, Plan/Organize, Organization of Materials and Task Completion). Two additional measures were included at age 15 (BRIEF Self-Report and the CANTAB Stockings of Cambridge (SOC)).

RESULTS

Girls with PCE were perceived by caregivers to have more behavioral regulation problems at age 12 (p<0.005) and more metacognitive problems at age 12 (p<0.003) than NCE females, but there was no association for males. PCE girls improved in behavioral regulation (p<0.05) and metacognition (p<0.04) from 12 to 15years compared to NCE girls based on caregiver report. By self-report PCE was associated with problems of inhibition (p<0.006). Girls with PCE performed more poorly on number of moves to complete the SOC, requiring planning and problem solving, than NCE girls.

CONCLUSION

Prenatally cocaine exposed girls were perceived by caregivers as having problems of behavioral regulation, and by self-report, inhibitory control problems. Girls with PCE also performed more poorly on a task of planning and problem solving at age 15 which corresponded to caregiver report at age 12. Early assessment and remediation of these weaknesses in girls may improve school performance and behavior associated with poor EF.

Different neural substrates for executive functions in youths with ADHD: a diffusion spectrum imaging tractography study

BACKGROUND

The relationship between white-matter tracts and executive functions (EF) in attention deficit hyperactivity disorder (ADHD) has not been well studied and previous studies mainly focused on frontostriatal (FS) tracts. The authors explored the microstructural property of several fibre tracts hypothesized to be involved in EF, to correlate their microstructural property with EF, and to explore whether such associations differ between ADHD and typically developing (TD) youths.

METHOD

We assessed 45 youths with ADHD and 45 individually matched TD youths with a computerized test battery for multiple dimensions of EF. From magnetic resonance imaging, FS tract, superior longitudinal fasciculus (SLF), arcuate fasciculus (AF) and cingulum bundle (CB) were reconstructed by diffusion spectrum imaging tractography. The generalized fractional anisotropy (GFA) values of white-matter tracts were computed to present microstructural property of each tract.

RESULTS

We found lower GFA in the left FS tract, left SLF, left AF and right CB, and poorer performance in set-shifting, sustained attention, cognitive inhibition and visuospatial planning in ADHD than TD. The ADHD and TD groups demonstrated different association patterns between EF and fibre tract microstructural property. Most of the EF were associated with microstructural integrity of the FS tract and CB in TD youths, while with that of the FS tract, SLF and AF in youths with ADHD.

CONCLUSIONS

Our findings support that the SLF, AF and CB also involve in a wide range of EF and that the main fibre tracts involved in EF are different in youths with ADHD.

Structural imaging for addiction medicine: From neurostructure to neuroplasticity

Quantitative morphometry and diffusion tensor imaging have provided new insights into structural brain changes associated with drugs of abuse. In this chapter, we review recent studies using these methods to investigate structural brain abnormalities associated with excessive use of marijuana, stimulants, and opiates. Although many brain regions have been associated with structural abnormalities following abuse of these drugs, brain systems underlying inhibition, mood regulation, and reward are particularly involved. Candidate pathological mechanisms underlying these structural abnormalities include the direct toxic effects of the drugs, neuroinflammation, ischemia, hemorrhage, and abnormal brain development. Returning damaged brain areas to neural health would involve enhancing neuroplasticity. Behavioral, environmental, pharmacological, and cell-based therapies have been correlated with enhanced neuroplasticity following brain injury, providing a basis for new treatments of brain changes associated with excessive drug use. When testing new treatments, structural imaging may prove useful in selecting patients, monitoring recovery, and perhaps, tailoring interventions.

Executive function and cortical thickness in youths prenatally exposed to cocaine, alcohol and tobacco

Small and detrimental, albeit inconsistent, effects of prenatal cocaine exposure (PCE) during early childhood have been reported. The teratogenic effects of prenatal alcohol (PAE) and tobacco exposure (PTE) on neurobehavior are more firmly established than PCE. We tested if co-exposure to all three drugs could be related to greater differences in brain structure than exposure to cocaine alone. Participants (n=42, PCE=27; age range=14-16 years) received an executive function battery prior to a T1-weighted 3T structural MRI scan. Cortical thickness was measured using FreeSurfer (v5.1). Fetal drug exposure was quantified through maternal self-reports usage during pregnancy. Using general linear modeling, we found no main effects of PCE on cortical thickness, but significant main effects of PAE and PTE in superior and medial frontal regions, after co-varying for the effects of age, sex, and each drug of exposure. Significant alcohol-by-tobacco interactions, and significant cocaine-by-alcohol interactions on cortical thickness in medial parietal and temporal regions were also observed. Poly-drug exposure and cognitive function also showed significant interactions with cortical thickness: lower cortical thickness was associated with better performance in PCE-exposed adolescents. Results suggest that although children with PCE have subtle but persistent brain cortical differences until mid-to-late adolescence.

Effect of cocaine dependence on brain connections: clinical implications

Cocaine dependence (CD) is associated with several cognitive deficits. Accumulating evidence, based on human and animal studies, has led to models for interpreting the neural basis of cognitive functions as interactions between functionally related brain regions. In this review, we focus on magnetic resonance imaging (MRI) studies using brain connectivity techniques as related to CD. The majority of these brain connectivity studies indicated that cocaine use is associated with altered brain connectivity between different structures, including cortical-striatal regions and default mode network. In cocaine users some of the altered brain connectivity measures are associated with behavioral performance, history of drug use, and treatment outcome. The implications of these brain connectivity findings to the treatment of CD and the pros and cons of the major brain connectivity techniques are discussed. Finally potential future directions in cocaine use disorder research using brain connectivity techniques are briefly described.

White matter abnormalities and impaired attention abilities in children born very preterm

While attention impairments are commonly observed in very preterm (<32weeks' gestational age) children, neuroanatomical correlates of these difficulties are unclear. We aimed to determine whether the microstructural organization of key white matter tracts thought to be involved in attention (cingulum bundle, superior longitudinal fasciculi, reticular activating system, and corpus callosum) were altered in very preterm children compared with term-born controls. We also aimed to determine whether alterations in microstructural organization of these tracts were associated with attention functioning in very preterm children. One hundred and forty-nine very preterm children and 36 term-born controls underwent neuroimaging and assessment of their attention abilities at 7years. Constrained spherical deconvolution and probabilistic tractography was used to identify the key white matter tracts. Altered microstructural organization and reduced tract volume within reticular activating system and corpus callosum were found in the very preterm group compared with the control group. Diffusion and volume changes in the cingulum bundle, superior longitudinal fasciculi, reticular activating system, and corpus callosum were related to variations in attention functioning in the very preterm children. These findings emphasize that white matter tract integrity is associated with later attentional abilities in very preterm children.

Who Gets Head Trauma or Recruited in Mild Traumatic Brain Injury Research?

Mild traumatic brain injury (mTBI) is a public health problem. Outcome from mTBI is heterogeneous in part due to pre-injury individual differences that typically are not well described or understood. Pre-injury health characteristics of all consecutive patients (n=3023) who underwent head computed tomography due to acute head trauma in the emergency department of Tampere University Hospital, Finland, between August 2010 and July 2012 were examined. Patients were screened to obtain a sample of working age adults with no pre-injury medical or mental health problems who had sustained a "pure" mTBI. Of all patients screened, 1990 (65.8%) fulfilled the mTBI criteria, 257 (8.5%) had a more severe TBI, and 776 (25.7%) had a head trauma without obvious signs of brain injury. Injury-related data and participant-related data (e.g., age, sex, diagnosed diseases, and medications) were collected from hospital records. The most common pre-injury diseases were circulatory (39.4%-43.2%), neurological (23.7%-25.2%), and psychiatric (25.8%-27.5%) disorders. Alcohol abuse was present in 18.4%-26.8%. The most common medications were for cardiovascular (33.1%-36.6%), central nervous system (21.4%-30.8%), and blood clotting and anemia indications (21.5%-22.6%). Of the screened patients, only 2.5% met all the enrollment criteria. Age, neurological conditions, and psychiatric problems were the most common reasons for exclusion. Most of the patients sustaining an mTBI have some pre-injury diseases or conditions that could affect clinical outcome. By excluding patients with pre-existing conditions, the patients with known risk factors for poor outcome remain poorly studied.

Altered white matter in cocaine-dependent subjects with traumatic brain injury: A diffusion tensor imaging study

BACKGROUND

Diffusion tensor imaging (DTI) is a useful technique for non-invasively investigating the microstructural organization of white matter (WM), and the most consistent DTI finding regarding cocaine-related WM alterations is in the corpus callosum (CC). WM injury has also been observed in subjects with traumatic brain injury (TBI), including in the CC.

METHODS

We used DTI to test if the WM microstructure is relatively more impaired in cocaine-dependent subjects who had suffered a mild TBI (mTBI). Fractional anisotropy (FA), which reflects the degree of alignment of cellular structures within fiber tracts and their structural integrity, was compared across cocaine-dependent subjects with mTBI (COCTBI group, n = 9), matched cocaine-dependent subjects without TBI (COC group, n = 12), and matched healthy controls (CTL group, n = 12).

RESULTS

The COCTBI group had significantly lower FA in the genu, body, and splenium of CC, than the CTL group whenever the education was controlled or not. The COC group had significantly lower FA in the left and right anterior corona radiata than the CTL group only when the education was controlled. There was no significant difference in FA between the COC and COCTBI groups.

CONCLUSION

Cocaine dependence (or mTBI) related WM impairments in the CC were not detectable in this small subject sample. The significant finding in the CC suggests that the concurrence of cocaine dependence and mTBI might result in more severe damage to the CC, which could even be detected in small sample size.

Developmental consequences of fetal exposure to drugs: what we know and what we still must learn

Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.

Prenatal cocaine exposure and age of sexual initiation: direct and indirect effects

BACKGROUND

Prenatal cocaine exposure (PCE) has been linked to child behavior problems and risky behavior during adolescence such as early substance use. Behavior problems and early substance use are associated with earlier initiation of sexual behavior. The goal of this study was to examine the direct and indirect effects of PCE on sexual initiation in a longitudinal birth cohort, about half of whom were exposed to cocaine in utero.

METHODS

Women were interviewed twice prenatally, at delivery, and 1, 3, 7, 10, 15, and 21 years postpartum. Offspring (52% female, 54% African American) were assessed at delivery and at each follow-up phase with age-appropriate assessments. At age 21, 225 offspring reported on their substance use and sexual behavior.

RESULTS

First trimester cocaine exposure was a significant predictor of earlier age of first intercourse in a survival analysis, after controlling for race, sociodemographic characteristics, caregiver pre- and postnatal substance use, parental supervision, and child's pubertal timing. However, the association between PCE and age of first sexual intercourse was mediated by adolescent marijuana and alcohol use prior to age 15.

CONCLUSIONS

Most of the effect of PCE on age of sexual initiation occurred between the ages of 13-18, when rates of initiation were approximately 10% higher among exposed offspring. This effect was mediated by early adolescent substance use. These results have implications for identification of the exposed offspring at greatest risk of HIV risk behaviors and early, unplanned pregnancy.

White matter correlates of cognitive inhibition during development: a diffusion tensor imaging study

Inhibitory control and cognitive flexibility are two key executive functions that develop in childhood and adolescence, increasing one's capacity to respond dynamically to changing external demands and refrain from impulsive behaviors. These gains evolve in concert with significant brain development. Magnetic resonance imaging studies have identified numerous frontal and cingulate cortical areas associated with performance on inhibition tasks, but less is known about the involvement of the underlying anatomical connectivity, namely white matter. Here we used diffusion tensor imaging (DTI) to examine correlations between a DTI-derived parameter, fractional anisotropy (FA) of white matter, and performance on the NEPSY-II Inhibition test (Naming, Inhibition and Switching conditions) in 49 healthy children aged 5-16years (20 females; 29 males). First, whole brain voxel-based analysis revealed several clusters in the frontal projections of the corpus callosum, where higher FA was associated with worse inhibitory performance, as well as several clusters in posterior brain regions and one in the brainstem where higher FA was associated with better cognitive flexibility (in the Switching task), suggesting a dichotomous relationship between FA and these two aspects of cognitive control. Tractography through these clusters identified several white matter tracts, which were then manual traced in native space. Pearson's correlations confirmed associations between higher FA of frontal projections of the corpus callosum with poorer inhibitory performance (independent of age), though associations with Switching were not significant. Post-hoc evaluation suggested that FA of orbital and anterior frontal projections of the corpus callosum also mediated performance differences across conditions, which may reflect differences in self-monitoring or strategy use. These findings suggest a link between the development of inhibition and cognitive control with that of the underlying white matter, and may help to identify deviations of neurobiology in adolescent psychopathology.

Adolescent risk-taking as a function of prenatal cocaine exposure and biological sex

OBJECTIVE

To examine the effects of prenatal cocaine exposure and biological sex on adolescent risk-taking while controlling for early environmental risk.

METHODS

Adolescents (n=114, mean age=16) were grouped according to high and low risk-taking propensity as measured by the Balloon Analogue Risk Task (BART). Prenatal cocaine exposure was assessed at birth, while environmental risk was assessed at three points during early childhood.

RESULTS

A binary regression analysis indicated that males were 3.5 times more likely than females to be high risk-takers. Biological sex and prenatal cocaine exposure interacted such that exposed males were most likely to be high risk-takers while exposed females were the least likely to be high risk-takers. This pattern held after controlling for prenatal alcohol exposure and early environmental risk. Early environmental risk did not predict adolescent risk-taking.

CONCLUSIONS

These findings complement and extend earlier research demonstrating that prenatal cocaine exposure interacts with biological sex in domains related to inhibitory control, emotion regulation, antisocial behavior, and health risk behaviors during preadolescence.