The mentalizing network and theory of mind mediate adjustment after childhood traumatic brain injury

Delineating the impact of childhood traumatic brain injury (TBI) on long-term depressive symptom severity: Does sub-acute brain morphometry prospectively predict 2-year outcome?

Despite evidence of a link between childhood TBI and heightened risk for depressive symptoms, very few studies have examined early risk factors that predict the presence and severity of post-injury depression beyond 1-year post injury. This longitudinal prospective study examined the effect of mild-severe childhood TBI on depressive symptom severity at 2-years post-injury. It also evaluated the potential role of sub-acute brain morphometry and executive function (EF) in prospectively predicting these long-term outcomes. The study involved 81 children and adolescents with TBI, and 40 age-and-sex matched typically developing (TD) controls. Participants underwent high-resolution structural magnetic resonance imaging (MRI) sub-acutely at five weeks post-injury (M = 5.55; SD = 3.05 weeks) and EF assessments were completed at 6-months post-injury. Compared to TD controls, the TBI group had significantly higher overall internalizing symptoms and were significantly more likely to exhibit clinically significant depressive symptoms at 2-year follow-up. The TBI group also displayed significantly lower EF and altered sub-acute brain morphometry in EF-related brain networks, including the default-mode network (DMN), salience network (SN) and central executive network (CEN). Mediation analyses revealed significant indirect effects of CEN morphometry on depression symptom severity, such that lower EF mediated the prospective association between altered CEN morphometry and higher depression symptoms in the TBI group. Parallel mediation analyses including grey matter morphometry of a non-EF brain network (i.e., the mentalising network) were not statistically significant, suggesting some model specificity. The findings indicate that screening for early neurostructural and neurocognitive risk factors may help identify children at elevated risk of depressive symptoms following TBI. For instance, children at greatest risk of post-injury depression symptoms could be identified based in part on neuroimaging of networks implicated in EF and post-acute assessments of executive function, which could support more effective allocation of limited intervention resources.

Association of neurostructural biomarkers with secondary attention-deficit/hyperactivity disorder (ADHD) symptom severity in children with traumatic brain injury: a prospective cohort study

BACKGROUND

Despite a well-established link between childhood traumatic brain injury (TBI) and elevated secondary attention-deficit/hyperactivity disorder (s-ADHD) symptomology, the neurostructural correlates of these symptoms are largely unknown. Based on the influential 'triple-network model' of ADHD, this prospective longitudinal investigation aimed to (i) assess the effect of childhood TBI on brain morphometry of higher-order cognitive networks proposed to play a key role in ADHD pathophysiology, including the default-mode network (DMN), salience network (SN) and central executive network (CEN); and (ii) assess the independent prognostic value of DMN, SN and CEN morphometry in predicting s-ADHD symptom severity after childhood TBI.

METHODS

The study sample comprised 155 participants, including 112 children with medically confirmed mild-severe TBI ascertained from consecutive hospital admissions, and 43 typically developing (TD) children matched for age, sex and socio-economic status. High-resolution structural brain magnetic resonance imaging (MRI) sequences were acquired sub-acutely in a subset of 103 children with TBI and 34 TD children. Parents completed well-validated measures of ADHD symptom severity at 12-months post injury.

RESULTS

Relative to TD children and those with milder levels of TBI severity (mild, complicated mild, moderate), children with severe TBI showed altered brain morphometry within large-scale, higher-order cognitive networks, including significantly diminished grey matter volumes within the DMN, SN and CEN. When compared with the TD group, the TBI group showed significantly higher ADHD symptomatology and higher rates of clinically elevated symptoms. In multivariable models adjusted for other well-established risk factors, altered DMN morphometry independently predicted higher s-ADHD symptomatology at 12-months post-injury, whilst SN and CEN morphometry were not significant independent predictors.

CONCLUSIONS

Our prospective study findings suggest that neurostructural alterations within higher-order cognitive circuitry may represent a prospective risk factor for s-ADHD symptomatology at 12-months post-injury in children with TBI. High-resolution structural brain MRI has potential to provide early prognostic biomarkers that may help early identification of high-risk children with TBI who are likely to benefit from early surveillance and preventive measures to optimise long-term neuropsychiatric outcomes.

Relational vs representational social cognitive processing: a coordinate-based meta-analysis of neuroimaging data

The neurocognitive bases of social cognition have been framed in terms of representing others' actions through the mirror system and their mental states via the mentalizing network. Alongside representing another person's actions or mental states, however, social cognitive processing is also shaped by their (mis)match with one's own corresponding states. Here, we addressed the distinction between representing others' states through the action observation or mentalizing networks (i.e. representational processing) and detecting the extent to which such states align with one's own ones (i.e. relational processing, mediated by social conflict). We took a meta-analytic approach to unveil the neural bases of both relational and representational processing by focusing on previously reported brain activations from functional magnetic resonance imaging studies using false-belief and action observation tasks. Our findings suggest that relational processing for belief and action states involves, respectively, the left and right temporo-parietal junction, likely contributing to self-other differentiation. Moreover, distinct sectors of the posterior fronto-medial cortex support social conflict processing for belief and action, possibly through the inhibition of conflictual representations. These data might pave the way for further studies addressing social conflict as an important component of normal and pathological processing, and inform the design of rehabilitative treatments for social deficits.

Social Functioning and Autistic Behaviors in Youth Following Acquired Brain Injury

Children and adolescents who survive the pediatric intensive care unit (PICU) with an acquired brain injury (ABI) often demonstrate a variety of physical, cognitive, emotional/behavioral, and social sequelae termed post-intensive care syndrome (PICS). Social communication and interaction challenges have also been observed clinically, and there is growing literature documenting these occurrences in youth following ABI. The extent of these social changes varies among patients, and a subset of patients go on to exhibit social and behavioral profiles closely resembling those of autistic youth. We reviewed empirical research regarding social functioning in youth following ABI, as well as the overlap between individuals with ABI and autistic youth, published from January 2009 to August 2022 on PubMed and Scopus databases. Clinical case examples from a well-established post-PICU follow-up program are also provided to exemplify the complexity of this phenomenon.

Development of the mentalizing network structures and theory of mind in extremely preterm youth

Adolescents born preterm (<37 weeks of gestation) are at elevated risk for deficits in social cognition and peer relationships. Theory of Mind (ToM) is a complex form of social cognition important for regulating social interactions. ToM and the underlying mentalizing network continue to develop across adolescence. The present study recruited 48 adolescents (12-17 years old) who were either born extremely preterm (EPT; <28 weeks of gestation) or full-term (FT) at birth. Cortical thickness, gray matter volume and surface area were measured in four regions of the mentalizing network: the temporoparietal junction, anterior temporal cortex, posterior superior temporal sulcus and frontal pole (mBA10). We also assessed the adolescents' performance on a ToM task. Findings revealed both group differences and group-by-age interaction effects in the gray matter indices within the temporal lobe regions of the mentalizing network. The EPT group also performed significantly worse than the FT group on the ToM task. The cortical structural measures that discriminated the EPT and FT groups were not related to ToM performance. These results highlight altered developmental changes in brain regions underlying mentalizing functions in EPT adolescents relative to FT controls.

Neural alterations in working memory of mild-moderate TBI: An fMRI study in Malaysia

Working memory (WM) encompasses crucial cognitive processes or abilities to retain and manipulate temporary information for immediate execution of complex cognitive tasks in daily functioning such as reasoning and decision-making. The WM of individuals sustaining traumatic brain injury (TBI) was commonly compromised, especially in the domain of WM. The current study investigated the brain responses of WM in a group of participants with mild-moderate TBI compared to their healthy counterparts employing functional magnetic resonance imaging. All consented participants (healthy: n = 26 and TBI: n = 15) performed two variations of the n-back WM task with four load conditions (0-, 1-, 2-, and 3-back). The respective within-group effects showed a right hemisphere-dominance activation and slower reaction in performance for the TBI group. Random-effects analysis revealed activation difference between the two groups in the right occipital lobe in the guided n-back with cues, and in the bilateral occipital lobe, superior parietal region, and cingulate cortices in the n-back without cues. The left middle frontal gyrus was implicated in the load-dependent processing of WM in both groups. Further group analysis identified that the notable activation changes in the frontal gyri and anterior cingulate cortex are according to low and high loads. Though relatively smaller in scale, this study was eminent as it clarified the neural alterations in WM in the mild-moderate TBI group compared to healthy controls. It confirmed the robustness of the phenomenon in TBI with the reproducibility of the results in a heterogeneous non-Western sample.

Executive function mediates the prospective association between neurostructural differences within the central executive network and anti-social behavior after childhood traumatic brain injury

BACKGROUND

Despite increasing evidence of a link between early life brain injury and anti-social behavior, very few studies have assessed factors that explain this association in children with traumatic brain injury (TBI). One hypothesis suggests that childhood TBI elevates risk for anti-social behavior via disruption to anatomically distributed neural networks implicated in executive functioning (EF). In this longitudinal prospective study, we employed high-resolution structural neuroimaging to (a) evaluate the impact of childhood TBI on regional morphometry of the central executive network (CEN) and (b) evaluate the prediction that lower EF mediates the prospective relationship between structural differences within the CEN and postinjury anti-social behaviors.

METHODS

This study involved 155 children, including 112 consecutively recruited, hospital-confirmed cases of mild-severe TBI and 43 typically developing control (TDC) children. T1-weighted brain magnetic resonance imaging (MRI) sequences were acquired sub-acutely in a subset of 137 children [TBI: n = 103; TDC: n = 34]. All participants were evaluated using direct assessment of EF 6 months postinjury, and parents provided ratings of anti-social behavior 12 months postinjury.

RESULTS

Severe TBI was associated with postinjury volumetric differences within the CEN and its putative hub regions. When compared with TD controls, the TBI group had significantly worse EF, which was associated with more frequent anti-social behaviors and abnormal CEN morphometry. Mediation analysis indicated that reduced EF mediated the prospective association between postinjury volumetric differences within the CEN and more frequent anti-social behavior.

CONCLUSIONS

Our longitudinal prospective findings suggest that detection of neurostructural abnormalities within the CEN may aid in the early identification of children at elevated risk for postinjury executive dysfunction, which may in turn contribute to chronic anti-social behaviors after early life brain injury. Findings underscore the potential value of early surveillance and preventive measures for children presenting with neurostructural and/or neurocognitive risk factors.

Improved neuropathological identification of traumatic brain injury through quantitative neuroimaging and neural network analyses: Some practical approaches for the neurorehabilitation clinician

BACKGROUND

Quantitative neuroimaging analyses have the potential to provide additional information about the neuropathology of traumatic brain injury (TBI) that more thoroughly informs the neurorehabilitation clinician.

OBJECTIVE

Quantitative neuroimaging is typically not covered in the standard radiological report, but often can be extracted via post-processing of clinical neuroimaging studies, provided that the proper volume acquisition sequences were originally obtained.

METHODS

Research and commercially available quantitative neuroimaging methods provide region of interest (ROI) quantification metrics, lesion burden volumetrics and cortical thickness measures, degree of focal encephalomalacia, white matter (WM) abnormalities and residual hemorrhagic pathology. If present, diffusion tensor imaging (DTI) provides a variety of techniques that aid in evaluating WM integrity. Using quantitatively identified structural and ROI neuropathological changes are most informative when done from a neural network approach.

RESULTS

Viewing quantitatively identifiable damage from a neural network perspective provides the neurorehabilitation clinician with an additional tool for linking brain pathology to understand symptoms, problems and deficits as well as aid neuropsychological test interpretation. All of these analyses can be displayed in graphic form, including3-D image analysis. A case study approach is used to demonstrate the utility of quantitative neuroimaging and network analyses in TBI.

CONCLUSIONS

Quantitative neuroimaging may provide additional useful information for the neurorehabilitation clinician.

Delineating the Nature and Correlates of Social Dysfunction after Childhood Traumatic Brain Injury Using Common Data Elements: Evidence from an International Multi-Cohort Study

Although childhood traumatic brain injury (TBI) has been linked to heightened risk of impaired social skills and behavior, current evidence is weakened by small studies of variable methodological quality. To address these weaknesses, this international multi-cohort study involved synthesis of data from two large observational cohort studies of complicated mild-severe child TBI in Australia and North America. Both studies adopted a unified approach to data collection and coding procedures, providing the opportunity to merge datasets from multiple, well-characterized cohorts for which gold standard measures of social outcomes were collected during the chronic recovery phase. The study involved 218 children, including 33 children with severe TBI, 83 children with complicated mild-moderate TBI, 59 children with orthopedic injury, and 43 age- and sex-matched typically developing control children. All injured children were recruited from academic children's hospitals and underwent direct cognitive assessments including measures of theory of mind (ToM) at least 1-year post- injury. Parents rated their child's social adjustment using standardized measures of social skills, communication and behavior. Results showed a brain-injury specific effect on ToM abilities, such that children with both complicated mild to moderate and severe TBI displayed significantly poorer ToM than children without TBI. In mediator models, poorer ToM predicted poorer parent-rated self-direction and social skills, as well as more frequent behavioral symptoms. The ToM mediated the effect of severe TBI on parent ratings of communication and social skills, as well as on overall behavior symptoms. The findings suggest that deficits in ToM are evident across the spectrum of TBI severity and represent one mechanism linking severe child TBI to long-term social adjustment difficulties. The findings underscore the value of large-scale data harmonization projects to increase the quality of evidence regarding the outcomes of TBI. Clinical and scientific implications are discussed.