Brain imaging findings in children and adolescents with mental disorders: A cross-sectional review

Challenges of implementing computer-aided diagnostic models for neuroimages in a clinical setting

Advances in artificial intelligence have cultivated a strong interest in developing and validating the clinical utilities of computer-aided diagnostic models. Machine learning for diagnostic neuroimaging has often been applied to detect psychological and neurological disorders, typically on small-scale datasets or data collected in a research setting. With the collection and collation of an ever-growing number of public datasets that researchers can freely access, much work has been done in adapting machine learning models to classify these neuroimages by diseases such as Alzheimer's, ADHD, autism, bipolar disorder, and so on. These studies often come with the promise of being implemented clinically, but despite intense interest in this topic in the laboratory, limited progress has been made in clinical implementation. In this review, we analyze challenges specific to the clinical implementation of diagnostic AI models for neuroimaging data, looking at the differences between laboratory and clinical settings, the inherent limitations of diagnostic AI, and the different incentives and skill sets between research institutions, technology companies, and hospitals. These complexities need to be recognized in the translation of diagnostic AI for neuroimaging from the laboratory to the clinic.

Visual search in neurodevelopmental disorders: evidence towards a continuum of impairment

Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses. N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.

Effect size of search superiority in autism spectrum disorder

This review of the literature in visual search superiority in autism was intended to quantify the effect size of visual search performance in autism. Not all studies have found an advantage within the autistic population. Early findings on search superiority have led to different proposed mechanisms for the observed results. A review of feature search found that the effect size was low across 15 included studies (Cohen's d 0.089 [-0.150 to 0.293]). However, the effect size was larger for more complex search paradigms using a conjunctive search strategy with Cohen's d showing a moderate effect of 0.223 (0.087 to 0.293). The majority of studies were limited to a small sample size and biased toward the high-functioning end of the autistic spectrum. The overall results indicate that within the autism spectrum disorder population there is a low to moderate search advantage compared to typically developing individuals.

Changes in neural activation underlying attention processing of emotional stimuli following treatment with positive search training in anxious children

Prior research indicates that positive search training (PST) may be a promising home-based computerised treatment for childhood anxiety disorders. It explicitly trains anxious individuals in adaptive, goal-directed attention-search strategies to search for positive and calm information and ignore goal-irrelevant negative cues. Although PST reduces anxiety symptoms, its neural effects are unknown. The main aim of this study was to examine changes in neural activation associated with changes in attention processing of positive and negative stimuli from pre- to post-treatment with PST in children with anxiety disorders. Children's neural activation was assessed with functional magnetic resonance imaging (fMRI) during a visual-probe task indexing attention allocation to threat-neutral and positive-neutral pairs. Results showed pre- to post-treatment reductions in anxiety symptoms and neural reactivity to emotional faces (angry and happy faces, relative to neutral faces) within a broad neural network linking frontal, temporal, parietal and occipital regions. Changes in neural reactivity were highly inter-correlated across regions. Neural reactivity to the threat-bias contrast reduced from pre- to post-treatment in the mid/posterior cingulate cortex. Results are considered in relation to prior research linking anxiety disorders and treatment effects with functioning of a broad limbic-cortical network involved in emotion reactivity and regulation, and integrative functions linking emotion, memory, sensory and motor processes and attention control.

Semi-Metric Topology of the Human Connectome: Sensitivity and Specificity to Autism and Major Depressive Disorder

Introduction

The human functional connectome is a graphical representation, consisting of nodes connected by edges, of the inter-relationships of blood oxygenation-level dependent (BOLD) time-series measured by MRI from regions encompassing the cerebral cortices and, often, the cerebellum. Semi-metric analysis of the weighted, undirected connectome distinguishes an edge as either direct (metric), such that there is no alternative path that is accumulatively stronger, or indirect (semi-metric), where one or more alternative paths exist that have greater strength than the direct edge. The sensitivity and specificity of this method of analysis is illustrated by two case-control analyses with independent, matched groups of adolescents with autism spectrum conditions (ASC) and major depressive disorder (MDD).

Results

Significance differences in the global percentage of semi-metric edges was observed in both groups, with increases in ASC and decreases in MDD relative to controls. Furthermore, MDD was associated with regional differences in left frontal and temporal lobes, the right limbic system and cerebellum. In contrast, ASC had a broadly increased percentage of semi-metric edges with a more generalised distribution of effects and some areas of reduction. In summary, MDD was characterised by localised, large reductions in the percentage of semi-metric edges, whilst ASC is characterised by more generalised, subtle increases. These differences were corroborated in greater detail by inspection of the semi-metric backbone for each group; that is, the sub-graph of semi-metric edges present in >90% of participants, and by nodal degree differences in the semi-metric connectome.

Conclusion

These encouraging results, in what we believe is the first application of semi-metric analysis to neuroimaging data, raise confidence in the methodology as potentially capable of detection and characterisation of a range of neurodevelopmental and psychiatric disorders.

Volumetric alterations in the heteromodal association cortex in children with autism spectrum disorder

BACKGROUND

We investigated if alterations in higher-order association areas related to schizophrenia, namely the heteromodal association cortex (HASC), are also observable in subjects with autism spectrum disorder (ASD).

METHODS

A group of 18 children with ASD and 18 healthy controls (HC) underwent magnetic resonance imaging (MRI). The examination comprised an analysis of group differences in gray matter (GM) volume, surface area (SA) and hemispheric lateralization.

RESULTS

Differences in GM volumes in children with ASD and HC were detected in frontal and parietal areas related to the HASC. No HASC structure that showed changes in GM volume exhibited differences in SA. Alterations in hemispheric lateralization between ASD and HC are seen in a frontal area of the HASC.

CONCLUSIONS

Our results indicate that changes in HASC areas are not restricted to schizophrenia, but extend to other psychiatric disorders, namely ASD. The lacking group differences in SA indicate that changes in GM volume are possibly evoked by other variables than SA in children with ASD.

Developmental meta-analyses of the functional neural correlates of bipolar disorder

IMPORTANCE

Bipolar disorder (BD) is a debilitating mental illness associated with high costs to diagnosed individuals and society. Within the past 2 decades, increasing numbers of children and adolescents have been diagnosed as having BD. While functional magnetic resonance imaging (fMRI) studies have begun to investigate the neural mechanisms underlying BD, few have directly compared differences in youths with BD and adults with BD (hereafter BD-youths and BD-adults, respectively).

OBJECTIVE

To test the hypothesis that BD-youths (<18 years old) would show greater convergence of amygdala hyperactivation and prefrontal cortical hypoactivation vs BD-adults.

DATA SOURCES

PubMed and PsycINFO databases were searched on July 17, 2013, for original, task-related coordinate-based fMRI articles.

STUDY SELECTION

In total, 21 pediatric studies, 73 adult studies, and 2 studies containing distinct pediatric and adult groups within the same study met inclusion criteria for our ALE analyses.

DATA EXTRACTION AND SYNTHESIS

Coordinates of significant between-group differences were extracted from each published study. Recent improvements in GingerALE software were used to perform direct comparisons of pediatric and adult fMRI findings. We conducted activation likelihood estimation (ALE) meta-analyses directly comparing the voxelwise convergence of fMRI findings in BD-youths vs BD-adults, both relative to healthy control (HC) participants.

RESULTS

Analyses of emotional face recognition fMRI studies showed significantly greater convergence of amygdala hyperactivation among BD-youths than BD-adults. More broadly, analyses of fMRI studies using emotional stimuli showed significantly greater convergence of hyperactivation among BD-youths than BD-adults in the inferior frontal gyrus and precuneus. In contrast, analyses of fMRI studies using nonemotional cognitive tasks and analyses aggregating emotional and nonemotional tasks showed significantly greater convergence of hypoactivation among BD-youths than BD-adults in the anterior cingulate cortex.

CONCLUSIONS AND RELEVANCE

Our data suggest that amygdala, prefrontal, and visual system hyperactivation is important in the emotional dysfunction present in BD-youths, as well as that anterior cingulate cortex hypoactivation is relevant to the cognitive deficits in BD-youths. Future studies are required to determine if the developmental fMRI differences between BD-youths and BD-adults identified by our ALE meta-analyses are useful as brain-based diagnostic or treatment markers of BD, including either longitudinal neuroimaging studies of BD-youths as they become adults or cross-sectional imaging studies directly comparing BD-youths with BD-adults.

Pediatric anxiety disorders: from neuroscience to evidence-based clinical practice

The objective of this narrative review of the literature is to describe the epidemiology, etiology, pathophysiology, diagnosis, and treatment of pediatric anxiety disorders. We aim to guide clinicians in understanding the biology of anxiety disorders and to provide general guidelines for the proper diagnoses and treatment of these conditions early in life. Anxiety disorders are prevalent, associated with a number of negative life outcomes, and currently under-recognized and under-treated. The etiology involves both genes and environmental influences modifying the neural substrate in a complex interplay. Research on pathophysiology is still in its infancy, but some brain regions, such as the amygdala and the prefrontal cortex, have been implicated in fear and anxiety. Current practice is to establish diagnosis based purely on clinical features, derived from clinical interviews with the child, parents, and teachers. Treatment is effective using medication, cognitive behavioral therapy, or a combination of both. An introduction to the neuroscience behind anxiety disorders combined with an evidence-based approach may help clinicians to understand these disorders and treat them properly in childhood.

Stratified medicine for mental disorders

There is recognition that biomedical research into the causes of mental disorders and their treatment needs to adopt new approaches to research. Novel biomedical techniques have advanced our understanding of how the brain develops and is shaped by behaviour and environment. This has led to the advent of stratified medicine, which translates advances in basic research by targeting aetiological mechanisms underlying mental disorder. The resulting increase in diagnostic precision and targeted treatments may provide a window of opportunity to address the large public health burden, and individual suffering associated with mental disorders. While mental health and mental disorders have significant representation in the "health, demographic change and wellbeing" challenge identified in Horizon 2020, the framework programme for research and innovation of the European Commission (2014-2020), and in national funding agencies, clear advice on a potential strategy for mental health research investment is needed. The development of such a strategy is supported by the EC-funded "Roadmap for Mental Health Research" (ROAMER) which will provide recommendations for a European mental health research strategy integrating the areas of biomedicine, psychology, public health well being, research integration and structuring, and stakeholder participation. Leading experts on biomedical research on mental disorders have provided an assessment of the state of the art in core psychopathological domains, including arousal and stress regulation, affect, cognition social processes, comorbidity and pharmacotherapy. They have identified major advances and promising methods and pointed out gaps to be addressed in order to achieve the promise of a stratified medicine for mental disorders.

Neuroimaging in children, adolescents and young adults with psychological trauma

Childhood psychological trauma is a strong predictor of psychopathology. Preclinical research points to the influence of this type of trauma on brain development. However, the effects of psychological trauma on the developing human brain are less known and a challenging question is whether the effects can be reversed or even prevented. The aim of this review is to give an overview of neuroimaging studies in traumatized juveniles and young adults up till 2012. Neuroimaging studies in children and adolescents with traumatic experiences were found to be scarce. Most studies were performed by a small number of research groups in the United States and examined structural abnormalities. The reduction in hippocampal volume reported in adults with PTSD could not be confirmed in juveniles. The most consistent finding in children and adolescents, who experienced psychological trauma are structural abnormalities of the corpus callosum. We could not identify any studies investigating treatment effects. Neuroimaging studies in traumatized children and adolescents clearly lag behind studies in traumatized adults as well as studies on ADHD and autism.

Body weight and ADHD: examining the role of self-regulation

OBJECTIVE

Attention-Deficit/Hyperactivity Disorder (ADHD) is a complex and heterogeneous childhood disorder that often coexists with other psychiatric and somatic disorders. Recently, a link between ADHD and body weight dysregulation has been reported and often interpreted as impaired self-regulation that is shared between the two conditions. The objective of this study is to investigate the relation between body weight/BMI and cognitive, emotional and motor characteristics in children with ADHD.

METHODS

284 ADHD children were stratified by weight status/BMI according to WHO classification and compared with regard to their neurocognitive characteristics, motivational style, and motor profile as assessed by a comprehensive battery of tests. All comparisons were adjusted for demographic characteristics of relevance including, socioeconomic status (SES).

RESULTS

Both Obese and overweight ADHD children exhibited significantly lower SES compared to normal weight ADHD children. No significant differences were observed between the three groups with regards to their neurocognitive, emotional and motor profile.

CONCLUSIONS

Our findings provide evidence that differences in weight/BMI are not accounted for by cognitive, motivational and motor profiles. Socio-economic characteristics are strongly associated with overweight and obesity in ADHD children and may inform strategies aimed at promoting healthier weight.

Major depressive disorder is associated with broad impairments on neuropsychological measures of executive function: a meta-analysis and review

Cognitive impairments are now widely acknowledged as an important aspect of major depressive disorder (MDD), and it has been proposed that executive function (EF) may be particularly impaired in patients with MDD. However, the existence and nature of EF impairments associated with depression remain strongly debated. Although many studies have found significant deficits associated with MDD on neuropsychological measures of EF, others have not, potentially due to low statistical power, task impurity, and diverse patient samples, and there have been no recent, comprehensive, meta-analyses investigating EF in patients with MDD. The current meta-analysis uses random-effects models to synthesize 113 previous research studies that compared participants with MDD to healthy control participants on at least one neuropsychological measure of EF. Results of the meta-analysis demonstrate that MDD is reliably associated with impaired performance on neuropsychological measures of EF, with effect sizes ranging from 0.32 to 0.97. Although patients with MDD also have slower processing speed, motor slowing alone cannot account for these results. In addition, some evidence suggests that deficits on neuropsychological measures of EF are greater in patients with more severe current depression symptoms, and those taking psychotropic medications, whereas evidence for effects of age was weaker. The results are consistent with the theory that MDD is associated with broad impairment in multiple aspects of EF. Implications for treatment of MDD and theories of EF are discussed. Future research is needed to establish the specificity and causal link between MDD and EF impairments.

Autism spectrum disorder: does neuroimaging support the DSM-5 proposal for a symptom dyad? A systematic review of functional magnetic resonance imaging and diffusion tensor imaging studies

A systematic review of 208 studies comprising functional magnetic resonance imaging and diffusion tensor imaging data in patients with 'autism spectrum disorder' (ASD) was conducted, in order to determine whether these data support the forthcoming DSM-5 proposal of a social communication and behavioral symptom dyad. Studies consistently reported abnormal function and structure of fronto-temporal and limbic networks with social and pragmatic language deficits, of temporo-parieto-occipital networks with syntactic-semantic language deficits, and of fronto-striato-cerebellar networks with repetitive behaviors and restricted interests in ASD patients. Therefore, this review partially supports the DSM-5 proposal for the ASD dyad.

Meta-analytic evidence for a superordinate cognitive control network subserving diverse executive functions

Classic cognitive theory conceptualizes executive functions as involving multiple specific domains, including initiation, inhibition, working memory, flexibility, planning, and vigilance. Lesion and neuroimaging experiments over the past two decades have suggested that both common and unique processes contribute to executive functions during higher cognition. It has been suggested that a superordinate fronto-cingulo-parietal network supporting cognitive control may also underlie a range of distinct executive functions. To test this hypothesis in the largest sample to date, we used quantitative meta-analytic methods to analyze 193 functional neuroimaging studies of 2,832 healthy individuals, ages 18-60, in which performance on executive function measures was contrasted with an active control condition. A common pattern of activation was observed in the prefrontal, dorsal anterior cingulate, and parietal cortices across executive function domains, supporting the idea that executive functions are supported by a superordinate cognitive control network. However, domain-specific analyses showed some variation in the recruitment of anterior prefrontal cortex, anterior and midcingulate regions, and unique subcortical regions such as the basal ganglia and cerebellum. These results are consistent with the existence of a superordinate cognitive control network in the brain, involving dorsolateral prefrontal, anterior cingulate, and parietal cortices, that supports a broad range of executive functions.

Neural substrates of childhood anxiety disorders: a review of neuroimaging findings

The development of fear is a normative process, and significant progress has been made in identifying fear neurocircuitry. The normal development of fear goes awry in children who develop anxiety disorders, and dysfunction in fear circuitry is likely. In this article, the authors present current knowledge about the neural basis of normal fear development and reviews findings from structural and functional neuroimaging studies of childhood anxiety disorders.

[Neuroimaging of psychiatric and pedopsychiatric disorders]

Over the last two decades, imaging techniques have allowed to establish the cerebral neurophysiologic correlates of psychiatric disorders and have highlighted the impact of psychopathologic events, therapeutic drugs, addictions, on the growth and plasticity of brain. In this review, we intend to illustrate how neuroimaging has improved our knowledge of such alterations in brain maturation (schizophrenia, autistic disorders), fronto-limbic (depressive syndromes) or fronto-striatal (compulsive disorders) regions in psychiatric illnesses, but also in psychopharmacology, or pedopsychiatry. Statistically significant alterations in the structure and/or function of brain are detected in all psychiatric disorders and these are often detectable already during childhood or teenage. Furthermore, neuroimaging has allowed to underline the importance of cerebral networks specific to each disorder, but also to uncover those which are common to different diseases provided that they share common clinical or cognitive features. Besides their value in basic research, neuroimaging findings have been key in changing the perception that society has of these diseases which contributed to their therapeutic approach.

CS02-03 - Imaging depression

Context

PET and MRI investigations performed in patient groups with major depressive disorder (MDD) by our team in Orsay searched for differences of regional brain measures during treatments.

Results

In the patient samples investigated, thorough analysis of cortical surface and metabolism suggested marked deviations in patients with resistant depression, while abnormalities of white matter microstructure were still present in euthymic patients (1–4). Relationship with treatment response was investigated (5). Recent ALE meta-analysis of Talairach’ spatial coordinates reported in the literature on adolescent MDD confirms that imaging techniques of brain function and brain structure revealed a consistent network of frontal limbic and subcortical regions (1)

Conclusion

While the diagnosis of MDD is symptom-based by definition, brain imaging research provided a bunch of convergent information on the regions mediating the depressive syndrome, and supports a significant proportion of MDD patients have brain deviations in both regional function and regional structure measurements.