Advancing understanding of the classification of broad autism phenotype and attention-deficit/hyperactivity disorder symptom dimensions within the Hierarchical Taxonomy of Psychopathology

Bifactor models of psychopathology using multi-informant and multi-instrument dimensional measures in the ABCD study

Background

Due to limitations of categorical definitions of mental illness, there is a need for quantitative empirical investigations of the dimensional structure of psychopathology. Using exploratory bifactor methods, this study investigated a comprehensive and representative structure of psychopathology in children to better understand how psychotic-like experiences (PLEs), autism spectrum disorder (ASD) symptoms, impulsivity, and sensitivity to reward and punishment, may be integrated into extant general factor models of psychopathology.

Methods

We used seven child-report and three parent-report instruments capturing diverse mental health symptoms in 11,185 children aged 9-10 from the Adolescent Brain Cognitive DevelopmentSM (ABCD) Study. We built on previous modeling frameworks by conducting both split sample and full sample factor analytic approaches that harnessed recent methodological advances in bifactor exploratory structural equation modeling (B-ESEM) to examine a wide range of psychopathology measures not previously integrated into a single analysis. Validity of psychopathology dimensions was examined by investigating associations with sex, age, cognition, imaging measures, and medical service usage.

Results

All four factor analytic models showed excellent fit and similar structure within informant. PLEs loaded most highly onto a general psychopathology factor, suggesting that they may reflect non-specific risk for mental illness. ASD symptoms loaded separately from attention/hyperactivity symptoms. Symptoms of impulsivity and sensitivity to reward and punishment loaded onto specific factors, distinct from externalizing and internalizing factors. All identified factors were associated with clinically relevant risk factors, providing preliminary evidence for their construct validity.

Conclusion

By integrating diverse child-report and parent-report psychopathology measures for children in the ABCD sample, we deliver data on the quantitative structure of psychopathology for an exceptionally large set of measurements and discuss implications for the field.

An Initial Investigation of the Joint Classification of Hypomania- and Neurodevelopmental Disorder-Relevant Dimensions Within the Hierarchical Taxonomy of Psychopathology

We examined hierarchical structural models of psychopathology in samples of (a) adults recruited online and screened based on psychopathology history (N = 429) and (b) undergraduates (N = 529) to inform classification of neurodevelopmental disorder (NDD)- and hypomania-relevant dimensions within the Hierarchical Taxonomy of Psychopathology (HiTOP). Results differed across samples in some ways, but converged to indicate that some NDD- and hypomania-relevant dimensions aligned closely with different HiTOP spectra. For example, some hypomania-relevant dimensions (e.g., affective lability) overlapped strongly with the internalizing spectrum, whereas others (e.g., self-perceived charisma) were reverse-indicators of detachment. Examination of cross-sectional and prospective correlates for emergent factors also was informative in some ways. This included NDD-relevant and disinhibited externalizing dimensions associating robustly with treatment seeking history and recent experiences of distress. These results provide initial insights into classifying NDD- and hypomania-relevant dimensions within the HiTOP and indicate a need for future research in this area.

An Exploratory Study of MMPI-2-RF Personality and Psychopathology Profiles of Adults with Autism Spectrum Disorder without Intellectual Disability

OBJECTIVE

More empirical research is needed to disentangle the phenotypes of autism spectrum disorder (ASD) and cluster C personality symptomatology (CCPD), as both show similarities in their clinical presentation. We explored personality and psychopathology dimensions as conceptualized in contemporary dimensional taxonomies (i.e., hierarchical taxonomy of psychopathology; HiTOP) in adults with ASD without intellectual disability operationalized by the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF).

METHOD

Applying secondary analytic processes using clinical data, we cross-examined the MMPI-2-RF profiles of adults with ASD (n = 28) compared to adults with Cluster C personality disorders (CCPD; n = 28) and a control group (n = 28) by conducting nonparametric tests and assessing effect sizes.

RESULTS

The profiles of the ASD and CCPD groups evidenced to be similar, and both average clinical profiles diverged from the average control group profiles by elevated levels of demoralization, internalizing, and somatization symptomatology. There were small differences between the average profiles of adults with ASD and adults with CCPD. Additional research using dimensional measures of psychopathology could elucidate the dimensional phenotypes of ASD and CCPD.

CONCLUSIONS

Based on the results in this study, the MMPI-2-RF may not meaningfully discriminate between the two clinical presentations, with the exception of various externalizing scales.

The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project design and methodologies: a dimensional approach to understanding neurobiological and genetic aetiology

Background

ASD and ADHD are prevalent neurodevelopmental disorders that frequently co-occur and have strong evidence for a degree of shared genetic aetiology. Behavioural and neurocognitive heterogeneity in ASD and ADHD has hampered attempts to map the underlying genetics and neurobiology, predict intervention response, and improve diagnostic accuracy. Moving away from categorical conceptualisations of psychopathology to a dimensional approach is anticipated to facilitate discovery of data-driven clusters and enhance our understanding of the neurobiological and genetic aetiology of these conditions. The Monash Autism-ADHD genetics and neurodevelopment (MAGNET) project is one of the first large-scale, family-based studies to take a truly transdiagnostic approach to ASD and ADHD. Using a comprehensive phenotyping protocol capturing dimensional traits central to ASD and ADHD, the MAGNET project aims to identify data-driven clusters across ADHD-ASD spectra using deep phenotyping of symptoms and behaviours; investigate the degree of familiality for different dimensional ASD-ADHD phenotypes and clusters; and map the neurocognitive, brain imaging, and genetic correlates of these data-driven symptom-based clusters.

Methods

The MAGNET project will recruit 1,200 families with children who are either typically developing, or who display elevated ASD, ADHD, or ASD-ADHD traits, in addition to affected and unaffected biological siblings of probands, and parents. All children will be comprehensively phenotyped for behavioural symptoms, comorbidities, neurocognitive and neuroimaging traits and genetics.

Conclusion

The MAGNET project will be the first large-scale family study to take a transdiagnostic approach to ASD-ADHD, utilising deep phenotyping across behavioural, neurocognitive, brain imaging and genetic measures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00457-3.