Amygdala response to emotional faces in adolescents with persistent post-concussion symptoms

A review of brain regions and associated post-concussion symptoms

The human brain is an exceptionally complex organ that is comprised of billions of neurons. Therefore, when a traumatic event such as a concussion occurs, somatic, cognitive, behavioral, and sleep impairments are the common outcome. Each concussion is unique in the sense that the magnitude of biomechanical forces and the direction, rotation, and source of those forces are different for each concussive event. This helps to explain the unpredictable nature of post-concussion symptoms that can arise and resolve. The purpose of this narrative review is to connect the anatomical location, healthy function, and associated post-concussion symptoms of some major cerebral gray and white matter brain regions and the cerebellum. As a non-exhaustive description of post-concussion symptoms nor comprehensive inclusion of all brain regions, we have aimed to amalgamate the research performed for specific brain regions into a single article to clarify and enhance clinical and research concussion assessment. The current status of concussion diagnosis is highly subjective and primarily based on self-report of symptoms, so this review may be able to provide a connection between brain anatomy and the clinical presentation of concussions to enhance medical imaging assessments. By explaining anatomical relevance in terms of clinical concussion symptom presentation, an increased understanding of concussions may also be achieved to improve concussion recognition and diagnosis.

Emotional Regulation and Adolescent Concussion: Overview and Role of Neuroimaging

Emotional dysregulation symptoms following a concussion are associated with an increased risk for emotional dysregulation disorders (e.g., depression and anxiety), especially in adolescents. However, predicting the emergence or worsening of emotional dysregulation symptoms after concussion and the extent to which this predates the onset of subsequent psychiatric morbidity after injury remains challenging. Although advanced neuroimaging techniques, such as functional magnetic resonance imaging and diffusion magnetic resonance imaging, have been used to detect and monitor concussion-related brain abnormalities in research settings, their clinical utility remains limited. In this narrative review, we have performed a comprehensive search of the available literature regarding emotional regulation, adolescent concussion, and advanced neuroimaging techniques in electronic databases (PubMed, Scopus, and Google Scholar). We highlight clinical evidence showing the heightened susceptibility of adolescents to experiencing emotional dysregulation symptoms following a concussion. Furthermore, we describe and provide empirical support for widely used magnetic resonance imaging modalities (i.e., functional and diffusion imaging), which are utilized to detect abnormalities in circuits responsible for emotional regulation. Additionally, we assess how these abnormalities relate to the emotional dysregulation symptoms often reported by adolescents post-injury. Yet, it remains to be determined if a progression of concussion-related abnormalities exists, especially in brain regions that undergo significant developmental changes during adolescence. We conclude that neuroimaging techniques hold potential as clinically useful tools for predicting and, ultimately, monitoring the treatment response to emotional dysregulation in adolescents following a concussion.

Frontoamygdala hyperconnectivity predicts affective dysregulation in adolescent moderate-severe TBI

In survivors of moderate to severe traumatic brain injury (msTBI), affective disruptions often remain underdetected and undertreated, in part due to poor understanding of the underlying neural mechanisms. We hypothesized that limbic circuits are integral to affective dysregulation in msTBI. To test this, we studied 19 adolescents with msTBI 17 months post-injury (TBI: M age 15.6, 5 females) as well as 44 matched healthy controls (HC: M age 16.4, 21 females). We leveraged two previously identified, large-scale resting-state (rsfMRI) networks of the amygdala to determine whether connectivity strength correlated with affective problems in the adolescents with msTBI. We found that distinct amygdala networks differentially predicted externalizing and internalizing behavioral problems in patients with msTBI. Specifically, patients with the highest medial amygdala connectivity were rated by parents as having greater externalizing behavioral problems measured on the BRIEF and CBCL, but not cognitive problems. The most correlated voxels in that network localize to the rostral anterior cingulate (rACC) and posterior cingulate (PCC) cortices, predicting 48% of the variance in externalizing problems. Alternatively, patients with the highest ventrolateral amygdala connectivity were rated by parents as having greater internalizing behavioral problems measured on the CBCL, but not cognitive problems. The most correlated voxels in that network localize to the ventromedial prefrontal cortex (vmPFC), predicting 57% of the variance in internalizing problems. Both findings were independent of potential confounds including ratings of TBI severity, time since injury, lesion burden based on acute imaging, demographic variables, and other non-amygdalar rsfMRI metrics (e.g., rACC to PCC connectivity), as well as macro- and microstructural measures of limbic circuitry (e.g., amygdala volume and uncinate fasciculus fractional anisotropy). Supporting the clinical significance of these findings, patients with msTBI had significantly greater externalizing problem ratings than healthy control participants and all the brain-behavior findings were specific to the msTBI group in that no similar correlations were found in the healthy control participants. Taken together, frontoamygdala pathways may underlie chronic dysregulation of behavior and mood in patients with msTBI. Future work will focus on neuromodulation techniques to directly affect frontoamygdala pathways with the aim to mitigate such dysregulation problems.

Depressive Symptoms in Individuals With Persistent Postconcussion Symptoms: A Systematic Review and Meta-Analysis

IMPORTANCE

Approximately 15% to 30% of individuals with a history of concussion present with persistent postconcussion symptoms (PPCS). Individuals with PPCS are at greater risk of experiencing depressive symptoms.

OBJECTIVE

To synthesize the association between depressive symptoms and PPCS in children, adolescents, and adults via meta-analysis and to investigate potential moderators of that association.

DATA SOURCES

Systematic search of Ovid Medline, CINAHL, PsycInfo, and Embase from 1995 to January 2022 was performed. Additionally, references from included studies were hand-searched to ensure relevant articles were captured in the search.

STUDY SELECTION

Studies that involved participants who experienced PPCS and quantified depressive symptoms were included. The definition of PPCS was limited to physician-diagnosed or self-reported concussion, with symptoms lasting for a minimum of 4 weeks postinjury. Two authors independently screened all articles to determine study eligibility.

DATA EXTRACTION AND SYNTHESIS

Study characteristics were extracted independently by 2 trained investigators. Study data were meta-analyzed using a random-effects meta-analysis.

EXPOSURE

PPCS.

MAIN OUTCOMES AND MEASURES

The the primary outcome was depressive symptoms.

RESULTS

Data were extracted from 18 studies with a total of 9101 participants. Of the 18 studies, all were cohort studies, and 13 (72%) comprised adult populations. The mean (SD) time since concussion was 21.3 (18.7) weeks. After accounting for potential publication bias, the random-effects meta-analysis found a significant positive association between PPCS and depressive symptoms, (odds ratio, 4.56; 95% CI, 2.82-7.37; P < .001). There were no significant moderators, likely due to the small number of studies included.

CONCLUSIONS AND RELEVANCE

In this meta-analysis, experiencing PPCS was associated with a higher risk of experiencing depressive symptoms. There are several important clinical and health policy implications of the findings. Most notably, the development of strategies for effective prevention and earlier intervention to optimize mental health recovery following a concussion should be supported.

A Scoping Review of Magnetic Resonance Modalities Used in Detection of Persistent Postconcussion Symptoms in Pediatric Populations

Up to 30% of youth with concussion experience PPCSs (PPCS) lasting 4 weeks or longer, and can significantly impact quality of life. Magnetic resonance imaging (MRI) has the potential to increase understanding of causal mechanisms underlying PPCS. However, there are no clear modalities to assist in detecting PPCS. This scoping review aims to synthesize findings on utilization of MRI among children and youth with PPCS, and summarize progress and limitations. Thirty-six studies were included from 4907 identified papers. Many studies used multiple modalities, including (1) structural (n = 27) such as T1-weighted imaging, diffusion weighted imaging, and susceptibility weighted imaging; and (2) functional (n = 23) such as functional MRI and perfusion-weighted imaging. Findings were heterogeneous among modalities and regions of interest, which warrants future reviews that report on the patterns and potential advancements in the field. Consideration of modalities that target PPCS prediction and sensitive modalities that can supplement a biopsychosocial approach to PPCS would benefit future research.

Classification Criteria and Rates of Persistent Postconcussive Symptoms in Children: A Systematic Review and Meta-Analysis

OBJECTIVE

To provide a systematic review of studies examining the proportion of children with persistent postconcussive symptoms (PPCS) and to examine potential moderators of prevalence.

STUDY DESIGN

Searches were conducted in MEDLINE, Embase, PsycINFO, Scopus, and Cochrane Central Register of Controlled Trials on April 16, 2020. Criteria for study inclusion were children aged <18 years with concussion or mild traumatic brain injury, operational definition of PPCS, assessment of postconcussive symptoms at least 4 weeks postinjury, sample sizes and proportion with PPCS available, and study published in English. Definition of PPCS, sample size, proportion of participants identified with PPCS, child sex and age at injury, time postinjury, premorbid symptoms, diagnosis (concussion or mild traumatic brain injury), and study publication year were extracted from each article. Study quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Thirteen studies, with a total of 5307 participants, were included in our analysis. The proportion of children identified with PPCS was 35.1% (weighted average; 95% CI, 26.3%-45.0%). The prevalence of PPCS was higher in older and female children who presented for care at concussion clinics, and in more recent publications.

CONCLUSIONS

Approximately one-third of children with concussion/mild traumatic brain injury will experience PPCS. Age, sex, and point of care could help identify children at high risk for PPCS.

A Review of Family Environment and Neurobehavioral Outcomes Following Pediatric Traumatic Brain Injury: Implications of Early Adverse Experiences, Family Stress, and Limbic Development

Pediatric traumatic brain injury (TBI) is a public health crisis, with neurobehavioral morbidity observed years after an injury associated with changes in related brain structures. A substantial literature base has established family environment as a significant predictor of neurobehavioral outcomes following pediatric TBI. The neural mechanisms linking family environment to neurobehavioral outcomes have, however, received less empiric study in this population. In contrast, limbic structural differences as well as challenges with emotional adjustment and behavioral regulation in non-TBI populations have been linked to a multitude of family environmental factors, including family stress, parenting style, and adverse childhood experiences. In this article, we systematically review the more comprehensive literature on family environment and neurobehavioral outcomes in pediatric TBI and leverage the work in both TBI and non-TBI populations to expand our understanding of the underlying neural mechanisms. Thus, we summarize the extant literature on the family environment's role in neurobehavioral sequelae in children with TBI and explore potential neural correlates by synthesizing the wealth of literature on family environment and limbic development, specifically related to the amygdala. This review underscores the critical role of environmental factors, especially those predating the injury, in modeling recovery outcomes post-TBI in childhood, and discusses clinical and research implications across pediatric populations. Given the public health crisis of pediatric TBI, along with the context of sparse available medical interventions, a broader understanding of factors contributing to outcomes is warranted to expand the range of intervention targets.