Evidence for a general factor model of ADHD in adults

Validation and bifactor structure of the French Adult ADHD Symptoms Rating Scale v1.1 (ASRS)

BACKGROUND

Three scoring methods for the widely available Adult ADHD Symptoms Rating Scale v1.1 (ASRS) have been proposed to screen for ADHD, but these three methods have rarely been compared against formal clinical diagnoses. We aimed to validate the French version of the ASRS against a clinical interview using DSM-IV and DSM-5 diagnostic algorithms.

METHODS

One hundred five adults from a convenience sample were evaluated with the ASRS and the DIVA 2.0, using both DSM-IV and DSM-5 criteria. We used Confirmatory Factor Analysis to investigate the underlying structure of the ASRS. Sensitivity, specificity, and classification accuracy were compared between the rating algorithms of the ASRS.

RESULTS

The full score method had worse predictive performance than the Screener and the 2-stage scoring method. All characteristics of the three scoring methods for the ASRS were worse when applying DSM-5 criteria. The best-fitting structure was a bi-factor model with a general ADHD factor and three specific factors.

CONCLUSIONS

ADHD was best conceived as a one-dimensional construct. The 2-stage scoring method superseded the Screener with comparable sensitivity and specificity.

Development of a human-analogue, 3-symptom domain Dog ADHD and Functionality Rating Scale (DAFRS)

The family dog, in its natural environment, exhibits neuropsychological deficits redolent of human psychiatric disorders, including behaviours that are similar to human attention-deficit/hyperactivity disorder (ADHD) symptoms. Based on standard questionnaire methods in humans, we aimed to develop and validate a detailed, psychometrically improved tool to assess owner views on relevant dog behaviours. We modified available questionnaires by adding items that allow for separate analysis of impulsivity, and items on functional impairment. We collected data from 1168 owners for different validation steps of the new questionnaire and, similarly to assessment of humans where teachers also evaluate as an expert control, we collected data from dog trainers. Exploratory and confirmatory factor analysis revealed 3 factors: inattention (IA), hyperactivity (H) and impulsivity (I), corresponding to all three human symptom dimensions in dogs. Test-retest analyses showed excellent agreement between measurements for all factors. Similarly to findings with humans, trainer-owner rating comparisons showed fair (IA) to moderate (H, I) agreement. As in humans, greater ADHD scores were associated with greater functional impairment scores. We suggest that in dogs, similarly to humans, parallel examination of (extreme) ADHD and functional impairment scores could help distinguish diagnosable individuals, after further validation of the questionnaire using a relevant behaviour test.

Focusing Narrowly on Model Fit in Factor Analysis Can Mask Construct Heterogeneity and Model Misspecification: Applied Demonstrations across Sample and Assessment Types

This study builds upon research indicating that focusing narrowly on model fit when evaluating factor analytic models can lead to problematic inferences regarding the nature of item sets, as well as how models should be applied to inform measure development and validation. To advance research in this area, we present concrete examples relevant to researchers in clinical, personality, and related subfields highlighting two specific scenarios when an overreliance on model fit may be problematic. Specifically, we present data analytic examples showing that focusing narrowly on model fit may lead to (a) incorrect conclusions that heterogeneous item sets reflect narrower homogeneous constructs and (b) the retention of potentially problematic items when developing assessment measures. We use both interview data from adult outpatients (N = 2,149) and self-report data from adults recruited online (N = 547) to demonstrate the importance of these issues across sample types and assessment methods. Following demonstrations with these data, we make recommendations focusing on how other model characteristics (e.g., factor loading patterns; carefully considering the content and nature of factor indicators) should be considered in addition to information provided by model fit indices when evaluating factor analytic models.

The factor structure of attention-deficit/hyperactivity disorder in schoolchildren

BACKGROUND

Most studies support a bifactor model of childhood ADHD with two specific factors. However, several studies have not compared this model with a bifactor model with three specific factors, few have tested the actual strength of the factors, and none have examined whether "talks excessively" should be treated as a hyperactivity versus impulsivity symptom in children with ADHD.

AIMS

To examine the factor structure of ADHD symptoms and evaluate the relative strength of potential factors.

METHODS

Parent-reports on the ADHD-Rating Scale (ADHD-RS-IV) were collected for 2044 schoolchildren from the general population and 147 children with ADHD from a clinical sample. Single-, two- and three-(correlated and bi-)factor models were tested using confirmatory factor analysis.

RESULTS

Most models had a satisfactory fit. However, a correlated three-factor model where "talks excessively" was included as an indicator of impulsivity, and especially a bifactor model with one strong, well-defined general and two/three (ICD-10 defined) weak specific factors fit the data slightly better than the remaining models.

CONCLUSIONS

The factor structure is best characterized by a bifactor model with a strong general factor and two/three weaker specific factors. Therefore, we suggest emphasizing the ADHD-RS-IV total score rather than the subscale scores in clinical practice.

An Examination of Relations Among Working Memory, ADHD Symptoms, and Emotion Regulation

Emotion regulation difficulties are present in many, if not most, children with attention-deficit/hyperactivity disorder (ADHD) and confer risk for a host of adverse outcomes. Little is known, however, regarding the neurocognitive and behavioral mechanisms that underlie these difficulties. A well-characterized, clinically evaluated sample of 145 children ages 8-13 years (M = 10.33, SD = 1.47; 55 girls; 69% White/non-Hispanic) were administered multiple, counterbalanced working memory tests and assessed for emotion dysregulation and ADHD symptoms via multiple-informant reports. Bias-corrected, bootstrapped conditional effects modeling indicated that underdeveloped working memory exerted significant direct effects on emotion regulation in all tested models as well as indirect effects on emotion regulation via parent-reported hyperactive/impulsive symptoms (95% CIs excluded zero). Interestingly, hyperactive/impulsive symptoms also predicted emotion dysregulation when controlling for the influence of working memory. Inattention failed to predict emotion regulation difficulties in all tested models (all 95% CIs included zero). This pattern of results replicated across parent and teacher models and were robust to control for mono-informant bias, age, and gender. These findings suggest that emotion dysregulation in ADHD reflects, in part, both a direct outcome of underdeveloped working memory and an affective outcome of hyperactive and/or impulsive symptomatology, both attributable to and independent of the role of underlying working memory deficits.

ADHD symptoms, the current symptom scale, and exploratory structural equation modeling: A psychometric study

The aim of the study was to use exploratory structural equation modelling (ESEM) to investigate support for an ADHD factor model with group factors for inattention (IA), hyperactivity (HY), and impulsivity (IM), as proposed in in ICD-10. A total of 202 adults (121 females and 81 males), aged between 18 and 35 years, from the general community, completed the Current Symptoms Scale (CSS). The results for the model showed good global fit, good convergent and divergent validities. However, the IA and IM factors, but not the HY factor, were clearly defined and demonstrated acceptable reliabilities. Taken together, these finding indicate that a revised ESEM model without the HY factor (i.e. with only the IA and IM symptoms) is an appropriate structure for modeling adult ratings of the ADHD behaviors described in the CSS. The taxonomic, theoretical and clinical implications of the findings for ADHD in general are discussed.

Age and Gender Measurement Noninvariance of the Adult ADHD Self-Report Scale Screener

Objective: The nature and form of demographics-related differences in ADHD self-reported symptoms across adulthood is currently poorly understood. This study explored the psychometrics of the Adult ADHD Self-Report Scale Screener (ASRS-6), including its age- and gender-related measurement invariance. Method: Structural equation models were used to analyze adult data-aged 16 to 95 years-from the 2007 British Adult Psychiatric Morbidity Survey. Results: The three-factor model (disorganization, inattention, hyperactivity) outperformed one- and two-factor models. Self-reported attentional deficits may be more pathognomonic of overall self-reported ADHD in adults than other symptoms. All items exhibited age measurement noninvariance while only a subset exhibited gender measurement noninvariance. Individuals who are male and younger tend to have lower thresholds for endorsement for ASRS-6 items than individuals who are female and older. Conclusion: The ASRS-6 does not appear to be unidimensional, and self-reported ASRS-6 symptomatology changes in meaning with age.

Unraveling the Optimum Latent Structure of Attention-Deficit/Hyperactivity Disorder: Evidence Supporting ICD and HiTOP Frameworks

Attention Deficit/hyperactivity disorder (ADHD) is conceptualized differently in the Diagnostic and Statistical Manual (DSM-5), the International Classification of Diseases-10 (ICD-10), and the Hierarchical Taxonomy of Psychopathology (HiTOP) frameworks. This study applied independent cluster confirmatory factor analysis (ICM-CFA), exploratory structure equation model with target rotation (ESEM), and the S-1 bi-factor CFA approaches to evaluate seven ADHD models yielded by different combinations of these taxonomic frameworks. Parents and teachers of a community sample of children (between 6 and 12 years of age) completed the Disruptive Behavior Rating Scale (for ADHD symptoms) and the Strengths and Difficulties Questionnaire (for validation). Our findings for both parent and teacher ratings provided the most support for the S-1 bi-factor CFA model comprised of (i) a g-factor based on ICD-10 impulsivity symptoms as the reference indicators and (ii) inattention and hyperactivity as specific factors. However, the hyperactivity-specific factor lacked clarity and reliability. Thus, our findings indicate that ADHD is best viewed as a disorder primarily reflecting impulsivity, though with a separable inattention (but no hyperactivity) component, i.e., "ADID (attention deficit/impulsivity disorder)." This model aligns with the HiTOP proposals.

Sex Differences in the Meaning of Parent and Teacher Ratings of ADHD Behaviors: An Observational Study

Objective: To test explanations for the underrecognition of female ADHD by examining differences in adult ratings of boys and girls matched for levels of directly observed ADHD behaviors. Method: In a secondary analysis of a population-based sample, 3- to 4-year-olds (n = 153, 79 male) and 8- to 9-year-olds (n = 144, 75 male) were grouped according to levels of directly observed ADHD behaviors (low/moderate/high). Groups were then compared with parent/teacher ADHD ratings. Results: There were no sex differences in levels of directly observed ADHD behaviors within groups. For preschoolers, parents' ratings of males, but not females, significantly increased across groups-mirroring levels of observed behaviors. For older children, both parent and teacher mean ratings were significantly higher for males than females across groups. Conclusion: Identified differences in adult ratings of males and females matched for directly observed behaviors may contribute to understanding the substantial ADHD underrecognition in females.

Acceptability of Family Violence: Underlying Ties Between Intimate Partner Violence and Child Abuse

Intimate partner violence (IPV) and child abuse (CA) are two forms of family violence with shared qualities and risk factors, and are forms of violence that tend to overlap. Acceptability of violence in partner relationships is a known risk factor in IPV just as acceptability of parent-child aggression is a risk factor in CA. We hypothesized that these acceptability attitudes may be linked and represent the expression of a general, underlying nonspecific acceptance of violence in close family relationships. The sample involved 164 male IPV offenders participating in a batterer intervention program. Implicit measures, which assess constructs covertly to minimize response distortions, were administered to assess acceptability of partner violence against women and acceptability of parent-child aggression. To determine whether acceptability attitudes regarding both forms of violence were related to a higher order construct tapping general acceptance of family violence, Bayesian confirmatory factor analyses were conducted. Findings supported a hierarchical (bifactor) model with a general factor expressing a nonspecific acceptance of family violence, and two specific factors reflecting acceptability of violence in intimate partner and parent-child relationships, respectively. This hierarchical model supporting a general acceptance of violence in close family relationships can inform future research aiming to better understand the connections between IPV and CA.

Rethinking hyperactivity in pediatric ADHD: Preliminary evidence for a reconceptualization of hyperactivity/impulsivity from the perspective of informant perceptual processes

Hyperactivity is a core ADHD symptom that has been both positively and negatively associated with cognition and functional outcomes. The reason for these conflicting findings is unclear but may relate to subjective assessments that conflate excess physical movement (hyperactivity) with verbally intrusive/impulsive behaviors. The current study adopted a model-driven, rational-empirical approach to distinguish excess physical movement symptoms from other, auditorily perceived behaviors assessed under the "hyperactivity/impulsivity" umbrella. We then tested this alternative conceptualization's fit, reliability, replicability, convergent/divergent validity via actigraphy, and generalizability across informants (parents, teachers) in a well-characterized, clinically evaluated sample of 132 children ages 8-13 years (M = 10.34, SD = 1.51; 47 girls; 67% White/non-Hispanic). The current DSM hyperactivity/impulsivity item pool can be reliably reclassified by knowledgeable judges into items reflecting excess physical movement (visual hyperactivity) and auditory interruptions (verbal intrusion). This bifactor structure showed evidence for multidimensionality and superior model fit relative to traditional hyperactivity/impulsivity models. The resultant visual hyperactivity factor was reliable, replicable, and showed strong convergent validity evidence via associations with objectively assessed hyperactivity. The verbal intrusion factor also showed evidence for reliability and explained a substantive portion of reliable variance, but demonstrated lower estimated replicability. These findings provide preliminary support for conceptualizing ADHD symptoms from the perspective of their cognitive-perceptual impact on others, as well as differentiating excess physical movement (hyperactivity) from other behaviors assessed under the hyperactivity/impulsivity umbrella. "Verbal intrusion" appears to provide a better explanation than "impulsivity" for the reliable, non-hyperactivity variance assessed by these items, but the current item set appears insufficient for replicable measurement of this construct. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

ADHD Symptoms in Adolescents' Everyday Life: Fluctuations and Symptom Structure Within and Between Individuals

Objective: This study investigated whether self-reported ADHD symptoms fluctuate substantially within adolescents from day to day, and examined the underlying symptom factor structure on a within- and between-person level. Method: Adolescents (N = 166) rated their ADHD symptoms over the phone on eight consecutive evenings (total ratings: n = 1,264). Results: ADHD symptoms showed substantial fluctuations within adolescents from day to day, as indicated by within-person standard deviations and intraclass correlation coefficients. Both a two-level factor model with three correlated factors (inattention, hyperactivity, impulsivity) and a two-level bifactor model with a general ADHD symptom factor and a specific inattention factor provided acceptable to good accounts of the structure underlying daily ADHD symptom ratings on the between- and the within-person level. Conclusion: The study demonstrates that adolescents' ADHD symptoms fluctuate from day to day and highlights the need for intensive diagnostic processes with repeated symptom assessments and interventions that address symptom fluctuations.

Practical consequences of model misfit when using rating scales to assess the severity of attention problems in children

OBJECTIVES

In this study, we examined the consequences of ignoring violations of assumptions underlying the use of sum scores in assessing attention problems (AP) and if psychometrically more refined models improve predictions of relevant outcomes in adulthood.

METHODS

Tracking Adolescents' Individual Lives data were used. AP symptom properties were examined using the AP scale of the Child Behavior Checklist at age 11. Consequences of model violations were evaluated in relation to psychopathology, educational attainment, financial status, and ability to form relationships in adulthood.

RESULTS

Results showed that symptoms differed with respect to information and difficulty. Moreover, evidence of multidimensionality was found, with two groups of items measuring sluggish cognitive tempo and attention deficit hyperactivity disorder symptoms. Item response theory analyses indicated that a bifactor model fitted these data better than other competing models. In terms of accuracy of predicting functional outcomes, sum scores were robust against violations of assumptions in some situations. Nevertheless, AP scores derived from the bifactor model showed some superiority over sum scores.

CONCLUSION

These findings show that more accurate predictions of later-life difficulties can be made if one uses a more suitable psychometric model to assess AP severity in children. This has important implications for research and clinical practice.

Examining the validity of the ADHD concept in adults and older adults

OBJECTIVE

It is crucial to clarify the structure of attention-deficit/hyperactivity disorder (ADHD) symptomatology in all age groups to determine how to best conceptualize this disorder across the lifespan. We tested the ADHD factor structure across adulthood and investigated independent associations with executive functions.

METHOD

Data from 645 adults aged 18-59 and 233 adults aged 60-85 were drawn from the Nathan Kline Institute Rockland Sample. Participants completed the Conners Adult ADHD Rating Scale and tests of executive functioning. Invariance of the ADHD factor structure was investigated using confirmatory factor analyses. Associations with cognition were explored using multiple linear regression.

RESULTS

Results confirmed a bifactor model with 3 specific factors (inattention, hyperactivity, and impulsivity). Factor loadings and item intercepts were invariant across ages. Levels of hyperactivity and impulsivity were lower in older adults. Inattentive symptoms in young adults were positively related to cognitive flexibility. In older adults, ADHD symptoms predicted poorer working memory.

CONCLUSION

ADHD symptoms manifest similarly across adulthood. The lack of robust associations between ADHD symptomatology and executive functions raises concerns about the usefulness of neuropsychological measures in diagnosing adult ADHD. These results support the validity of the ADHD concept in older adults but suggest a need for age-appropriate normative criteria.

Moderation of parenting by inhibitory control in the prediction of the common and unique variance of hyperactivity-impulsivity and inattention

This study examined whether the interaction between parenting and inhibitory control predicts hyperactivity-impulsivity and inattention in 195 children. Observation data of positive parenting were collected at 4 years, and mother reports of coercive parenting at 5 years, inhibitory control at 6 years, and hyperactivity-impulsivity/inattention at 7 years were obtained. The common and unique variance of hyperactivity-impulsivity and inattention symptoms were examined as outcomes using a bifactor model. Results indicated that positive parenting practices predicted lower levels of hyperactivity-impulsivity/inattention behaviors at age 7 only when children's inhibitory control was high. These results support the vantage sensitivity model, which posits that some individuals show an increased sensitivity to positive experiences exclusively, and support the appropriateness of a targeted prevention approach in early childhood.

Validity of the ADHD Bifactor Model in General Community Samples of Adolescents and Adults, and a Clinic-Referred Sample of Children and Adolescents

OBJECTIVE

This study examined the bifactor models of ADHD in three groups: adolescents from the general community ( n = 214), adults from the general community ( n = 366), and a clinic sample ( n = 245).

METHOD

For the adolescent sample, mothers provided ratings of the ADHD symptoms, and their teachers provided ratings for Emotional Symptoms, Conduct Problems, Hyperactivity, Peer Problems, and Prosocial Behavior. For the adult sample, all adults completed self-ratings of the ADHD symptoms and measures for depression, anxiety, and stress. For the clinic-referred sample, mothers provided ratings of the ADHD symptoms, and they were diagnosed for ADHD, Conduct Disorder/Oppositional Defiant Disorder, anxiety disorders, and depression disorders.

RESULTS

The findings for all samples supported the bifactor model, and there were differences in the way the general and specific factors correlated with the external variables.

CONCLUSION

The findings support the validity of the bifactor model.

The Willingness to Intervene in Cases of Intimate Partner Violence Against Women (WI-IPVAW) Scale: Development and Validation of the Long and Short Versions

Willingness to intervene when one becomes aware of a case of intimate partner violence against women (IPVAW) reflects the level of tolerance and acceptance of this type of violence in society. Increasing the likelihood of intervention to help victims of IPVAW is also a target for prevention strategies aiming to increase informal social control of IPVAW. In this study, we present the development and validation of the Willingness to Intervene in Cases of Intimate Partner Violence (WI-IPVAW) scale. We report data for both the long and short versions of the scale. We analyzed the latent structure, the reliability and validity of the WI-IPVAW across four samples (N = 1648). Factor analyses supported a bifactor model with a general non-specific factor expressing willingness to intervene in cases of IPVAW, and three specific factors reflecting different intervention preferences: a preference for setting the law enforcement process in motion ("calling the cops" factor), a preference for personal intervention ("personal involvement" factor), and a preference for non-intervention ("not my business" factor). Configural, metric, and partial scalar invariance across genders were supported. Two short versions of the scale, with nine and six items, respectively, were constructed on the base of quantitative and qualitative criteria. The long and short versions of the WI-IPVAW demonstrated both high reliability and construct validity, as they were strongly related to the acceptability of IPVAW, victim-blaming attitudes, perceived severity of IPVAW, and hostile sexism. These results confirm that both the long and short versions of the WI-IPVAW scale are psychometrically sound instruments to analyze willingness to intervene in cases of IPVAW in different settings and with different research needs (e.g., long versions for clinical and research settings, and short versions for large population surveys). The WI-IPVAW is also useful for assessing prevention policies and public education campaigns design to promote a more responsive social environment in cases of IPVAW, thus contributing to deter and reduce this major social and public health problem.

Evaluating the Hierarchical Structure of ADHD Symptoms and Invariance Across Age and Gender

The bifactor model of attention-deficit/hyperactivity disorder (ADHD) has been extensively explored, yet the tendency of the bifactor model to overfit data necessitates investigation of alternative, more parsimonious models, such as a modified bifactor structure. The present study used item response theory to compare unidimensional, correlated factors, bifactor, and modified bifactor models of ADHD symptoms in a clinical sample of youth ( N = 1,612) and examined differential item functioning (DIF) by age (<11 and ≥11 years) and gender. Results suggested that two restricted bifactor models showed superior fit compared with alternative models, and support strong general and inattention dimensions, with unreliable hyperactivity and impulsivity dimensions. No DIF was found across gender or age. The present study confirms that the general dimension (i.e., inhibition) and one specific dimension (i.e., sustained attention) represent distinct variability in ADHD symptoms that may improve prediction of symptom persistence, treatment response, or functional outcomes.

Does Sluggish Cognitive Tempo Fit Within a Bi-Factor Model of ADHD?

OBJECTIVE

Studies demonstrate sluggish cognitive tempo (SCT) symptoms to be distinct from inattentive and hyperactive-impulsive dimensions of ADHD. No study has examined SCT within a bi-factor model of ADHD, whereby SCT may form a specific factor distinct from inattention and hyperactivity/impulsivity while still fitting within a general ADHD factor, which was the purpose of the current study.

METHOD

A total of 168 children were recruited from an ADHD clinic. Most (92%) met diagnostic criteria for ADHD. Parents and teachers completed measures of ADHD and SCT.

RESULTS

Although SCT symptoms were strongly associated with inattention, they loaded onto a factor independent of ADHD g. Results were consistent across parent and teacher ratings.

CONCLUSION

SCT is structurally distinct from inattention as well as from the general ADHD latent symptom structure. Findings support a growing body of research suggesting SCT to be distinct and separate from ADHD.

Bifactor Models of Attention Deficit/Hyperactivity Symptomatology in Adolescents: Criterion Validity and Implications for Clinical Practice

This study evaluated the fit and criterion validity of a bifactor model for 18 DSM-IV attention deficit/hyperactivity disorder (ADHD) symptoms, along with nine supplementary symptoms that represented the manifestation of inattention and hyperactivity-impulsivity in adolescence and early adulthood. Participants included N = 172 adolescents who were diagnosed with combined type ADHD and who were enrolled in a treatment study. A bifactor model provided reasonably good fit to combined parent- and teacher-reported DSM symptoms and supplemental items at baseline prior to treatment. Across models, the general factor was characterized by high reliability (ω = .93, .95), while specific inattentive and hyperactive-impulsive factors were characterized by poor reliability (ω = .30-.50). With respect to criterion validity, the general ADHD and specific inattentive factors were uniquely associated with home and school impairment (R² = .13-.29) but not adolescent risk-tasking behavior. Results are discussed with respect to the ways in which bifactor models of ADHD inform the diagnostic criteria for ADHD.

Exploring DSM-5 ADHD criteria beyond young adulthood: phenomenology, psychometric properties and prevalence in a large three-decade birth cohort

BACKGROUND

There are still uncertainties on the psychometric validity of the DSM-5 attention deficit hyperactivity disorder (ADHD) criteria for its use in the adult population. We aim to describe the adult ADHD phenotype, to test the psychometric properties of the DSM-5 ADHD criteria, and to calculate the resulting prevalence in a population-based sample in their thirties.

METHOD

A cross-sectional evaluation using the DSM-5 ADHD criteria was carried out in 3574 individuals from the 1982 Pelotas Birth Cohort. Through receiver operator curve, latent and regression analyses, we obtained parameters on construct and discriminant validity. Still, prevalence rates were calculated for different sets of criteria.

RESULTS

The latent analysis suggested that the adult ADHD phenotype is constituted mainly by inattentive symptoms. Also, inattention symptoms were the symptoms most associated with impairment. The best cut-off for diagnosis was four symptoms, but sensitivity and specificity for this cut-off was low. ADHD prevalence rates were 2.1% for DSM-5 ADHD criteria and 5.8% for ADHD disregarding age-of-onset criterion.

CONCLUSIONS

The bi-dimensional ADHD structure proposed by the DSM demonstrated both construct and discriminant validity problems when used in the adult population, since inattention is a much more relevant feature in the adult phenotype. The use of the DSM-5 criteria results in a higher prevalence of ADHD when compared to those obtained by DSM-IV, and prevalence would increase almost threefold when considering current ADHD syndrome. These findings suggest a need for further refinement of the criteria for its use in the adult population.

Bifactor Models of Attention-Deficit/Hyperactivity Disorder (ADHD): An Evaluation of Three Necessary but Underused Psychometric Indexes

BACKGROUND

In the past decade, the bifactor model of attention-deficit/hyperactivity disorder (ADHD) has been extensively researched. This model consists of an ADHD general dimension and two specific factors: inattention and hyperactivity/impulsivity. All studies conclude that the bifactor is superior to the traditional two-correlated factors model, according to the fit obtained by factor analysis. However, the proper interpretation of a bifactor not only depends on the fit but also on the quality of the measurement model.

OBJECTIVE

To evaluate the model-based reliability, distribution of common variance and construct replicability of general and specific ADHD factors.

METHOD

We estimated expected common variance, omega hierarchical/subscale and H-index from standardized factor loadings of 31 ADHD bifactor models previously published.

RESULTS AND CONCLUSION

The ADHD general factor explained most of the common variance. Given the low reliable variance ratios, the specific factors were difficult to interpret. However, in clinical samples, inattention acquired sufficient specificity and stability for interpretation beyond the general factor. Implications for research and clinical practice are discussed.

Factorial Validity of the ADHD Adult Symptom Rating Scale in a French Community Sample: Results From the ChiP-ARD Study

OBJECTIVE

Recent publications reported that a bifactor model better represented the underlying structure of ADHD than classical models, at least in youth. The Adult ADHD Symptoms Rating Scale (ASRS) has been translated into many languages, but a single study compared its structure in adults across Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) and International Classification of Diseases (ICD-10) classifications.

METHOD

We investigated the factor structure, reliability, and measurement invariance of the ASRS among a community sample of 1,171 adults.

RESULTS

Results support a bifactor model, including one general ADHD factor and three specific Inattention, Hyperactivity, and Impulsivity factors corresponding to ICD-10, albeit the Impulsivity specific factor was weakly defined. Results also support the complete measurement invariance of this model across gender and age groups, and that men have higher scores than women on the ADHD G-factor but lower scores on all three S-factors.

CONCLUSION

Results suggest that a total ASRS-ADHD score is meaningful, reliable, and valid in adults. (J. of Att. Dis. 2016; 20(6) 530-541).

Co-occurring symptoms of attention deficit hyperactivity disorder (ADHD) in a population-based sample of adolescents screened for depression

BACKGROUND

Depression is common in adolescents, with a gender bias towards girls. Symptoms associated with attention deficit hyperactivity disorder (ADHD) tend to co-occur in depressed adolescents. This may be related to common features between the two symptom domains, but co-occurring ADHD symptoms may also inflate the severity of depression. The present study investigates the frequency and influence of ADHD symptoms co-occurring with depression in a gender balanced population-based sample of Norwegian adolescents.

METHODS

A sample of 9614 adolescents (16-19 years) completed a questionnaire including the short version of the Mood and Feelings Questionnaire (sMFQ) and the Adult ADHD Self-Report Scale (ASRS), with items reflecting symptoms associated with depression and ADHD, respectively. The sMFQ sum score was used as a proxy for severity of depression, and adolescents with a score equal to or above the 90th percentile were defined as depressed. A high response on any of the ASRS items was used to define the presence of an ADHD symptom, and the number of high scores was used to indicate severity.

RESULTS

ADHD symptoms were frequently reported by the adolescents, with a higher frequency in girls than in boys. The gender differences were, however, minor when the analysis was restricted to the adolescents defined as depressed. Each severe symptom reported on the ASRS contributed significantly to increase the sum score on the sMFQ, and more than 20 % of the adolescents defined as depressed reported six or more symptoms within the ASRS inattention subscale.

CONCLUSIONS

The results emphasize the importance of screening for symptoms associated with ADHD when assessing adolescents presenting symptoms indicating depression. Although girls reported higher frequency of symptoms within both domains, the gender bias was dependent on the overall symptom severity. Awareness of co-occurrence of symptoms and gender biases are of importance for both clinical work and future research on mental health and service use in adolescence.

Attention-deficit/hyperactivity disorder dimensionality: the reliable 'g' and the elusive 's' dimensions

The best structural model for attention-deficit/hyperactivity disorder (ADHD) symptoms remains a matter of debate. The objective of this study is to test the fit and factor reliability of competing models of the dimensional structure of ADHD symptoms in a sample of randomly selected and high-risk children and pre-adolescents from Brazil. Our sample comprised 2512 children aged 6-12 years from 57 schools in Brazil. The ADHD symptoms were assessed using parent report on the development and well-being assessment (DAWBA). Fit indexes from confirmatory factor analysis were used to test unidimensional, correlated, and bifactor models of ADHD, the latter including "g" ADHD and "s" symptom domain factors. Reliability of all models was measured with omega coefficients. A bifactor model with one general factor and three specific factors (inattention, hyperactivity, impulsivity) exhibited the best fit to the data, according to fit indices, as well as the most consistent factor loadings. However, based on omega reliability statistics, the specific inattention, hyperactivity, and impulsivity dimensions provided very little reliable information after accounting for the reliable general ADHD factor. Our study presents some psychometric evidence that ADHD specific ("s") factors might be unreliable after taking common ("g" factor) variance into account. These results are in accordance with the lack of longitudinal stability among subtypes, the absence of dimension-specific molecular genetic findings and non-specific effects of treatment strategies. Therefore, researchers and clinicians might most effectively rely on the "g" ADHD to characterize ADHD dimensional phenotype, based on currently available symptom items.

Bifactor Models Show a Superior Model Fit: Examination of the Factorial Validity of Parent-Reported and Self-Reported Symptoms of Attention-Deficit/Hyperactivity Disorders in Children and Adolescents

BACKGROUND

Various studies have demonstrated that bifactor models yield better solutions than models with correlated factors. However, the kind of bifactor model that is most appropriate is yet to be examined. The current study is the first to test bifactor models across the full age range (11-18 years) of adolescents using self-reports, and the first to test bifactor models with German subjects and German questionnaires.

SAMPLING AND METHODS

The study sample included children and adolescents aged between 6 and 18 years recruited from a German clinical sample (n = 1,081) and a German community sample (n = 642). To examine the factorial validity, we compared unidimensional, correlated factors and higher-order and bifactor models and further tested a modified incomplete bifactor model for measurement invariance.

RESULTS

Bifactor models displayed superior model fit statistics compared to correlated factor models or second-order models. However, a more parsimonious incomplete bifactor model with only 2 specific factors (inattention and impulsivity) showed a good model fit and a better factor structure than the other bifactor models. Scalar measurement invariance was given in most group comparisons.

CONCLUSION

An incomplete bifactor model would suggest that the specific inattention and impulsivity factors represent entities separable from the general attention-deficit/hyperactivity disorder construct and might, therefore, give way to a new approach to subtyping of children beyond and above attention-deficit/hyperactivity disorder.

Applying Bifactor Statistical Indices in the Evaluation of Psychological Measures

The purpose of this study was to apply a set of rarely reported psychometric indices that, nevertheless, are important to consider when evaluating psychological measures. All can be derived from a standardized loading matrix in a confirmatory bifactor model: omega reliability coefficients, factor determinacy, construct replicability, explained common variance, and percentage of uncontaminated correlations. We calculated these indices and extended the findings of 50 recent bifactor model estimation studies published in psychopathology, personality, and assessment journals. These bifactor derived indices (most not presented in the articles) provided a clearer and more complete picture of the psychometric properties of the assessment instruments. We reached 2 firm conclusions. First, although all measures had been tagged "multidimensional," unit-weighted total scores overwhelmingly reflected variance due to a single latent variable. Second, unit-weighted subscale scores often have ambiguous interpretations because their variance mostly reflects the general, not the specific, trait. Finally, we review the implications of our evaluations and consider the limits of inferences drawn from a bifactor modeling approach.

Using factor analytic models to examine the association between attention-deficit/hyperactivity disorder symptoms and health-related outcomes in a representative population survey

The objective of the study was to examine the factor structure of attention-deficit/hyperactivity disorder (ADHD) symptoms in a representative population survey of adults and the association of these factors with health outcomes. Hierarchical and correlated factor analysis models were compared, and regression analyses with these models were used to determine the associations with psychological distress and substance use problems. A total of 1449 adults 18-65 years of age participated in a cross-sectional survey over the phone. ADHD symptom data came from an ADHD screener (10 items), and health outcomes were assessed using a questionnaire measuring psychological distress and two measures of substance use problems. The hierarchical general factor models with specific factors best represented the structure of ADHD in this representative population survey. The general factor and residual inattention factor were significantly associated with psychological distress, and the general factor was associated with substance use problems. From the correlated factor models, the inattention factor was associated with psychological distress and the hyperactivity factor was related to substance use problems. The hierarchical and correlated factor models explained similar levels of variance in outcomes. The results replicate previous studies indicating that a model of ADHD symptoms with a unitary dimension and separable dimensions of residual inattention and hyperactivity/impulsivity demonstrates a better fit than correlated factor models. The ADHD general factor was consistently significantly related to outcomes.

ADHD in DSM-5: a field trial in a large, representative sample of 18- to 19-year-old adults

BACKGROUND

The DSM criteria for adult attention-deficit/hyperactivity disorder (ADHD) have not been tested in American Psychiatric Association (APA) field trials for either DSM-IV or DSM-5. This study aimed to assess: (a) the prevalence of ADHD according to DSM-5 criteria; (b) the factor solution that provides the best fit for ADHD symptoms; (c) the symptoms with the highest predictive value for clinical impairment; and (d) the best symptomatic threshold for each ADHD dimension (inattention and hyperactivity/impulsivity).

METHOD

Trained psychologists evaluated 4000 young adults from the 1993 Pelotas Birth Cohort Study with an instrument covering all DSM-5 ADHD criteria. A series of confirmatory factor analyses (CFAs) tested the best factor structure. Complex logistic regressions assessed differential contributions of each symptom to clinical impairment. Receiver-operating characteristic (ROC) analyses tested which would be the best symptomatic cut-off in the number of symptoms for predicting impairment.

RESULTS

The prevalence of DSM-5 ADHD was 3.55% [95% confidence interval (CI) 2.98-4.12]. The estimated prevalence of DSM-IV ADHD was 2.8%. CFA revealed that a bifactor model with a single general factor and two specific factors provided the best fit for DSM-5 symptoms. Inattentive symptoms continued to be the most important predictors of impairment in adults. The best cut-offs were five symptoms of inattention and four symptoms of hyperactivity/impulsivity.

CONCLUSIONS

Our results, combined with previous findings, suggest a 27% increase in the expected prevalence of ADHD among young adults, comparing DSM-IV to DSM-5 criteria. The DSM-5 symptomatic organization derived a similar factor structure for adults as DSM-IV symptoms. Data using DSM-5 criteria support lowering the symptomatic threshold for diagnosing ADHD in adults.

Hyperactivity and Motoric Activity in ADHD: Characterization, Assessment, and Intervention

The aim of the present literature review is threefold. (1) We will review theories, models, and studies on symptomatic hyperactivity and motoric activity in attention-deficit/hyperactivity disorder (ADHD). (2) Another focus will be on assessment methods that have been proven to be effective in the detection of hyperactivity and motoric activity in children, adolescents, and adults with and without ADHD and emerging areas of research in the field of ADHD. We will compare subjective methods (i.e., rating scales) and objective methods (i.e., accelerometers). (3) Finally, physical activity intervention studies aiming at a modification of activity and overactive behavior will be summarized that seem to be promising candidates for alleviating hyperactivity symptoms in children, adolescents, and adults with ADHD.

Bifactor latent structure of ADHD/ODD symptoms: predictions of dual-pathway/trait-impulsivity etiological models of ADHD

OBJECTIVE

To determine if ADHD/ODD symptoms are better represented by a bifactor model of disruptive behavior [general disruptive behavior factor along with specific inattention (IN), specific hyperactivity/impulsivity (HI), and specific oppositional defiant disorder (ODD) factors] than an ADHD-IN, ADHD-HI, and ODD three-factor model.

METHOD

Mothers' and fathers' ratings of ADHD-IN, ADHD-HI, and ODD symptoms in a community sample of 4,658 children and adolescents (53% female) from Brazil, Thailand, and the US were used to evaluate the measurement models.

RESULTS

The bifactor model of disruptive behavior provided a better fit than the three factor model. The bifactor model also occurred with mothers' and fathers' ratings of male and female children and adolescents.

CONCLUSIONS

Consistent with predictions derived from recently articulated dual-pathway and trait-impulsivity models of externalizing liability, and from behavioral genetics studies indicating near complete overlap in vulnerability to ADHD and ODD, ADHD and ODD symptoms arose from a single, general disruptive behavior factor, which accounted for all of the variance in HI subscale scores and over half of the variance IN and ODD subscales. Thus, IN, HI, and ODD subscale scores strongly reflect a general disruptive behavior factor – not the specific content of their respective constructs.

Replication and external validation of a bi-factor parameterization of attention deficit/hyperactivity symptomatology

This study evaluated the fit and criterion validity of a recently proposed bi-factor structure for attention deficit/hyperactivity disorder (ADHD) symptoms. Participants were 1,093 children, drawn from an ongoing prospective longitudinal study, whose ADHD symptoms were rated by parents and teachers when children were in 1st grade. The criterion validity of the bi-factor model was established using a range of school-based outcomes that included treatment utilization, teacher perceptions of the need for treatment, academic functioning, and peer and teacher relationship quality. Results indicated that a bi-factor model parameterization provided an equally good fit to parent, teacher, and combined reports of ADHD symptoms as did traditional 1-, 2-, and 3-factor models. However, in contrast to traditional models, the bi-factor parameterization acknowledged both the unity and diversity of ADHD symptoms. The general ADHD latent factor explained the vast majority of the observed variation in every symptom. Whereas the general ADHD latent factor was significantly associated with all 15 outcomes, the specific Inattentive factor explained unique variation in 9 (primarily the academically oriented) outcomes and the specific Hyperactive-Impulsive factor explained unique variation in 2 outcomes. The general ADHD factor was more strongly correlated with each of the observed ADHD symptom scores (total, inattentive, hyperactive-impulsive) than was either specific factor. Results are discussed with respect to how changes in the conceptualization of the factor structure correspond to recent changes to the diagnostic criteria for ADHD, as well as whether/how individual differences in inattention and hyperactivity-impulsivity might be used to differentiate children who are diagnosed with ADHD.

Rethinking ADHD and LD in DSM-5: proposed changes in diagnostic criteria

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is currently undergoing revision that will lead to a fifth edition (DSM-5) in 2013. This article first provides a brief synopsis of the DSM-5 administrative structure, procedures, and guiding principles to enhance understanding of how changes are made in the DSM. The next two sections (on attention-deficit/hyperactivity disorder and learning disorders, respectively) highlight the major concerns and controversies surrounding the DSM-IV diagnostic criteria for these two disorders and provide a rationale for the proposed changes to the criteria, along with a commentary on the empirical evidence on which the proposed changes were based.

The hierarchical factor model of ADHD: invariant across age and national groupings?

OBJECTIVE

To examine the factor structure of attention-deficit/hyperactivity disorder (ADHD) in a clinical sample of 1,373 children and adolescents with ADHD and their 1,772 unselected siblings recruited from different countries across a large age range. Hierarchical and correlated factor analytic models were compared separately in the ADHD and sibling samples, across three different instruments and across parent and teacher informants. Specific consideration was given to factorial invariance analyses across different ages and different countries in the ADHD sample.

METHOD

A sample of children and adolescents between 5 and 17 years of age with ADHD and their unselected siblings was assessed. Participants were recruited from seven European countries and Israel. ADHD symptom data came from a clinical interview with parents Parental Account of Childhood Symptoms and questionnaires from parents and teachers (Conners Parent and Teacher).

RESULTS

A hierarchical general factor model with two specific factors best represented the structure of ADHD in both the ADHD and unselected sibling groups, and across informants and instruments. The model was robust and invariant with regard to age differences in the ADHD sample. The model was not strongly invariant across different national groups in the ADHD sample, likely reflecting severity differences across the different centers and not any substantial difference in the clinical presentation of ADHD.

CONCLUSIONS

The results replicate previous studies of a model with a unitary ADHD component and separable specific traits of inattention and hyperactivity/impulsivity. The unique contribution of this study was finding support for this model across a large developmental and multinational/multicultural sample and its invariance across ages.