Is Poor Working Memory a Transdiagnostic Risk Factor for Psychopathology? J Abnorm Child Psychol. 2017;45:1477-1490. [PMID: 27783257 DOI: 10.1007/s10802-016-0219-8]

Transdiagnostic associations across communication, cognitive, and behavioural problems in a developmentally at-risk population: a network approach

BACKGROUND

Communication, behavioural, and executive function problems often co-occur in childhood. Previous attempts to identify the origins of these comorbidities have typically relied on comparisons of different deficit groups and/or latent variable models. Here we apply a network approach to a heterogeneous sample of struggling learners to conceptualise these comorbidities as a dynamic system of interacting difficulties.

METHODS

714 children struggling with attention, learning, and/or memory were included. The sample consisted of children with both diagnosed (41%) and undiagnosed difficulties. The conditional independence network of parent ratings of everyday behaviour, cognition, and communication was estimated.

RESULTS

A clustering coefficient identified four interconnected areas of difficulty: (1) structural language and learning; (2) pragmatics and peer relationships; (3) behavioural and emotional problems; and (4) cognitive skills. Emotional and behavioural symptoms shared multiple direct connections with pragmatic abilities and cognitive problems, but not with structural language skills or learning problems. Poor structural language and cognitive skills were associated with learning problems. Centrality indices highlighted working memory and language coherence as symptoms bridging different problem areas.

CONCLUSION

The network model identified four areas of difficulty and potential bridging symptoms. Although the current analytic framework does not provide causal evidence, it is possible that bridging symptoms may be the origins of comorbidities observed on a dimensional level; problems in these areas may cascade and activate problems in other areas of the network. The potential value of applying a dynamic systems network approach to symptoms of developmental disorders is discussed.

Measurement and Modulation of Working Memory-Related Oscillatory Abnormalities

Despite the critical role of working memory (WM) in neuropsychiatric conditions, there remains a dearth of available WM-targeted interventions. Gamma and theta oscillations as measured with electroencephalography (EEG) or magnetoencephalography (MEG) reflect the neural underpinnings of WM. The WM processes that fluctuate in conjunction with WM demands are closely correlated with WM test performance, and their EEG signatures are abnormal in several clinical populations. Novel interventions such as transcranial magnetic stimulation (TMS) have been shown to modulate these oscillations and subsequently improve WM performance and clinical symptoms. Systematically identifying pathological WM-related gamma/theta oscillatory patterns with EEG/MEG and developing ways to target them with interventions such as TMS is an active area of clinical research. Results hold promise for enhancing the outcomes of our patients with WM deficits and for moving the field of clinical neuropsychology towards a mechanism-based approach.

Parsing Heterogeneity in Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder with Individual Connectome Mapping

Traditional diagnostic systems for neurodevelopmental disorders define diagnostic categories that are heterogeneous in behavior and underlying neurobiological alterations. The goal of this study was to parse heterogeneity in a core executive function (EF), cognitive flexibility, in children with a range of abilities (N = 132; children with autism spectrum disorder, attention-deficit/hyperactivity disorder [ADHD], and typically developing children) using directed functional connectivity profiles derived from resting-state functional magnetic resonance imaging data. Brain regions activated in response to a cognitive flexibility task in adults were used to guide region-of-interest selection to estimate individual connectivity profiles in this study. We expected to find subgroups of children who differed in their network connectivity metrics and symptom measures. Unexpectedly, we did not find a stable or valid subgrouping solution, which suggests that categorical models of the neural substrates of cognitive flexibility in children may be invalid. Exploratory analyses revealed dimensional associations between network connectivity metrics and ADHD symptomatology and EF ability across the entire sample. Results shed light on the validity of conceptualizing the neural substrates of cognitive flexibility categorically in children. Ultimately, this work may provide a foundation for the development of a revised nosology focused on neurobiological substrates as an alternative to traditional symptom-based classification systems.

Executive Functions and Externalizing Symptoms: Common and Unique Associations

In discussing the four papers in this special issue, we provide our perspective on the authors' contributions and suggest directions for future research. First, we highlight the usefulness of the bi-factor model for investigating relations among specific aspects of executive functions (EFs) and externalizing symptoms. Next, we examine the role of EFs as a protective factor that can moderate the relation between risk factors - specifically, callous-unemotional behaviors - on externalizing symptoms. And finally, we address the contributions of innovative measurement approaches to understanding the relations between EFs and externalizing symptoms, using the state-space grid methodology as an example.

Relative importance of symptoms, cognition, and other multilevel variables for psychiatric disease classifications by machine learning

This study used machine-learning algorithms to make unbiased estimates of the relative importance of various multilevel data for classifying cases with schizophrenia (n = 60), schizoaffective disorder (n = 19), bipolar disorder (n = 20), unipolar depression (n = 14), and healthy controls (n = 51) into psychiatric diagnostic categories. The Random Forest machine learning algorithm, which showed best efficacy (92.9% SD: 0.06), was used to generate variable importance ranking of positive, negative, and general psychopathology symptoms, cognitive indexes, global assessment of function (GAF), and parental ages at birth for sorting participants into diagnostic categories. Symptoms were ranked most influential for separating cases from healthy controls, followed by cognition and maternal age. To separate schizophrenia/schizoaffective disorder from bipolar/unipolar depression, GAF was most influential, followed by cognition and paternal age. For classifying schizophrenia from all other psychiatric disorders, low GAF and paternal age were similarly important, followed by cognition, psychopathology and maternal age. Controls misclassified as schizophrenia cases showed lower nonverbal abilities, mild negative and general psychopathology symptoms, and younger maternal or older paternal age. The importance of symptoms for classification of cases and lower GAF for diagnosing schizophrenia, notably more important and distinct from cognition and symptoms, concurs with current practices. The high importance of parental ages is noteworthy and merits further study.

Socioemotional dispositions of children and adolescents predict general and specific second-order factors of psychopathology in early adulthood: A 12-year prospective study

We previously hypothesized that the ubiquitous, but patterned correlations among all dimensions of psychopathology reflect a hierarchy of progressively more nonspecific causal influences, with a general factor of psychopathology-also dubbed the p factor-reflecting the most transdiagnostic causal influences. We further hypothesized that the general factor is a manifestation of individual differences in 1 or more trait-like dispositions, particularly negative emotionality, that are nonspecifically associated with risk for essentially every dimension of psychopathology. We tested the hypothesis that this and other dispositions measured in childhood/adolescence significantly predict general and specific second-order dimensions of psychopathology in early adulthood. The latent general factor of psychopathology itself was correlated over time from 10-17 to 23-31 years of age even though it was defined by different informants and different dimensions of symptoms. Using a measure of dispositions that minimizes item contamination with psychopathology symptoms, parent-rated negative emotionality in childhood and adolescence predicted the general factor of psychopathology based on self-reported symptoms in early adulthood, whereas parent-rated daring predicted the specific adult externalizing psychopathology factor after correction for multiple tests. In addition, youth-rated negative emotionality and daring predicted specific adult externalizing psychopathology. These results over a span of 12 years suggests that the general factor is relatively stable over time and that associations of dispositional traits with second-order dimensions of psychopathology are enduring, sometimes across informants. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Attention-deficit/hyperactivity disorder: An integrated developmental psychopathology and Research Domain Criteria (RDoC) approach

Attention-deficit/hyperactivity disorder (ADHD) is characterized by heterogeneous behaviors and symptoms, developmental trajectories, and treatment response. Isolating intermediate phenotypes that are superior to current DSM-based nosology in order to explain such heterogeneity is integral to enhancing etiological theory, improving clinical assessment, predicting treatment response, and developing tailored treatments. To this end, this review provides an integrated developmental psychopathology and National Institute of Mental Health Research Domain Criteria (RDoC) approach to ADHD. In particular, associations between ADHD and RDoC domains of cognition (specifically working memory) and positive valence (reward anticipation/delay/receipt) are discussed. These domains are examined across behavioral and neurocircuitry levels of analysis and placed within a developmental context via examining associations among RDoC domains, relevant features of ADHD, and environmental correlates implicated across development. Limitations of the existing literature and proposed future directions are explored. Importantly, future work should focus on novel approaches that account for developmental shifts in functioning of relevant RDoC domains over time, as well as further examination of the interaction across RDoC domains and levels of analysis.

Transdiagnostic mechanisms of psychopathology in youth: Executive functions, dependent stress, and rumination

Executive function (EF) deficits have been proposed as transdiagnostic risk factors for psychopathology, and recent research suggests EF impairments are associated with what is shared across forms of psychopathology (p factor). However, most research has not employed methods that differentiate between EF components, and little is known about the mediating mechanisms linking EF and psychopathology dimensions. The current study tested associations between the latent unity/diversity model of EF and latent dimensions of psychopathology and investigated mediating mechanisms in a community sample of 292 youth age 13-22. The results confirmed the finding that poor EF is associated with internalizing psychopathology in older youth via higher dependent stress and rumination, and showed that this pathway was transdiagnostic, predicting the p factor rather than internalizing specifically. Links with psychopathology were specific to the common EF factor, rather than updating- or shifting-specific EF.

Effect of Foster Care Intervention on Trajectories of General and Specific Psychopathology Among Children With Histories of Institutional Rearing: A Randomized Clinical Trial

IMPORTANCE

It is unclear whether early institutional rearing is associated with more problematic trajectories of psychopathology from childhood to adolescence and whether assignment to foster care mitigates this risk.

OBJECTIVES

To examine trajectories of latent psychopathology factors-general (P), internalizing (INT), and externalizing (EXT)-among children reared in institutions and to evaluate whether randomization to foster care is associated with reductions in psychopathology from middle childhood through adolescence.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal, intent-to-treat randomized clinical trial was conducted in Bucharest, Romania, where children residing in 6 institutions underwent baseline testing and were then randomly assigned to a care as usual group (CAUG) or a foster care group (FCG). A matched sample of a never-institutionalized group (NIG) was recruited to serve as a comparison group. The study commenced in April 2001, and the most recent (age 16 years) follow-up started in January 2015 and is ongoing.

INTERVENTION

Institutionally reared children randomized to high-quality foster homes.

MAIN OUTCOMES AND MEASURES

Psychopathology was measured using the MacArthur Health and Behavior Questionnaire. Teachers and/or caregivers reported on symptoms of psychopathology in several domains.

RESULTS

A total of 220 children (50.0% female; 119 ever institutionalized) were included in the analysis at the mean ages of 8, 12, and 16 years. A latent bifactor model with general (P) and specific internalizing (INT) and externalizing (EXT) factors offered a good fit to the data. At age 8 years, CAUG (mean, 0.41; 95% CI, 0.17-0.67) and FCG (mean, 0.30; 95% CI, 0.04-0.53) had higher P than NIG (mean, -0.40; 95% CI, -0.56 to -0.18). By age 16 years, FCG (mean, 0.07; 95% CI, -0.18 to 0.29) had lower P than CAUG (mean, 0.37; 95% CI, 0.13-0.60). This effect was likely driven by modest declines in P from age 8 years to age 16 years among FCG (slope, -0.12; 95% CI, -0.26 to 0.04) compared with CAUG, who remained stably high over this period (slope, -0.02; 95% CI, -0.19 to 0.14). Moreover, CAUG and FCG showed increasing divergence in EXT over time, such that FCG (mean, -0.30; 95% CI, -0.58 to -0.02) had fewer problems than CAUG (mean, 0.05; 95% CI, -0.25 to 0.36) by age 16 years. No INT differences were observed.

CONCLUSIONS AND RELEVANCE

Institutionalization increases transdiagnostic vulnerability to psychopathology from childhood to adolescence, a period of significant social and biological change. Early assignment to foster care partially mitigates this risk, thus highlighting the importance of social enrichment in buffering the effects of severe early neglect on trajectories of psychopathology.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00747396.

A Hierarchical Model of Inhibitory Control

Inhibitory control describes the suppression of goal-irrelevant stimuli and behavioral responses. Current developmental taxonomies distinguish between Response Inhibition – the ability to suppress a prepotent motor response, and Attentional Inhibition – the ability to resist interference from distracting stimuli. Response Inhibition and Attentional Inhibition have exhibited moderately strong positive correlations in previous studies, suggesting they are closely related cognitive abilities. These results may reflect the use of cognitive tasks combining Stimulus–Stimulus- and Stimulus–Response-conflict as indicators of both constructs, which may have conflated their empirical association. Additionally, previous statistical modeling studies have not controlled for individual differences in Working Memory Capacity, which may account for some of the empirical overlap between Response Inhibition and Attentional Inhibition. The aim of the current study was to test a hierarchical model of inhibitory control that specifies Working Memory Capacity as a higher-order cognitive construct. Response Inhibition and Attentional Inhibition were conceptualized as lower-order cognitive mechanisms that should be empirically independent constructs apart from their shared reliance on Working Memory Capacity for active maintenance of goal-relevant representations. Measures of performance on modified stimulus–response compatibility tasks, complex memory span, and non-selective stopping tasks were obtained from 136 preadolescent children (M = 11 years, 10 months, SD = 8 months). Consistent with hypotheses, results from Structural Equation Modeling demonstrated that the Response Inhibition and Attentional Inhibition factors were empirically independent constructs that exhibited partial statistical dependence on the Working Memory Capacity factor. These findings have important implications for current theories and models of inhibitory control during development.

Chronic Stress Exposure and Generation Are Related to the P-Factor and Externalizing Specific Psychopathology in Youth

Psychopathology is posited to be transdiagnostically linked to chronic stress. Yet efforts to understand the specificity and directionality of these links have been sparse, and the ubiquitous comorbidity of psychopathology has made the seemingly nonspecific links between psychological disorders and chronic stress difficult to interpret. The current study used a latent dimensional bifactor model of psychopathology to account for comorbidity and a multiwave prospective design to disentangle temporal associations between psychopathology and chronic stress longitudinally during the critical adolescent period for psychopathology risk and stress reactivity. A community sample of 567 youth (55.5% female, age M = 11.8 at baseline, M = 15.1 at end of study) were followed prospectively for 3 years, with chronic stress assessed with the Youth Life Stress Interview and psychopathology symptoms assessed via both self and parent report. Exposure to chronic stress predicted what is common across forms of psychopathology (the p factor), which in turn predicted generation of chronic stress over time. After accounting for comorbidity via the p factor, externalizing behaviors also had specific transactional links to chronic stress, whereas links between internalizing psychopathology and chronic stress were completely accounted for by common psychopathology. The results provide the first direct evidence that chronic stress is transdiagnostically and reciprocally linked to psychopathology, during a critical youth period for psychopathology onset and stress reactivity.