Validation of population‐based ADHD subtypes and identification of three clinically impaired subtypes

Abstract

Statistically based classification methods have successfully refined ADHD into homogenous and heritable subtypes. External validity and impairment of these subtypes was examined using the Child Behavior Checklist (CBCL). We compared mean CBCL syndrome and competency t-scores across ADHD subtypes defined by latent class analysis in a sample of 1,346 individual twins from Missouri. The potential for comorbidity with conduct disorder (CD), oppositional defiant disorder (ODD), or major depression (MD) to increase impairment in specific ADHD subtypes was also examined. CBCL profiles confirm differences in severity, with more severe classes having increased syndrome scale and decreased competency scale CBCL scores. Clinically significant impairment was found for severe inattentive and combined subtypes and the mild combined subtype. Overall, the presence of comorbid CD, ODD, or MD did not result in increased ADHD subtype impairment. CBCL scores distinguish impairment in ADHD subtypes created through LCA. Comorbidity with CD, ODD, or MD does not significantly increase impairment among ADHD subtypes. The mild combined ADHD subtype represents a clinically significant but under-studied form of ADHD.

Co-transmission of conduct problems with attention-deficit/hyperactivity disorder: familial evidence for a distinct disorder

“…Our finding milder and more severe variants of ADHDct cases concurs with others from Latent Class Analyses, which have consistently identified distinctive ''moderate-ADHDct'' and ''severe-ADHDct'' subtypes across twin samples in the USA, , Brazil (Rohde et al 2001) and Australia (Rasmussen et al 2002). However, Latent Class Analysis has not so far identified severe-ADHDct associated with ODD or CD (Volk et al 2006), although the canonical correlation analysis by Mathias et al (2007) described an association of impulsive-conduct problems with inattentive and hyperactive components of ADHD and that impulsivity was the common construct underlying ADHD and CD.…”

ADHD Across Cultures: Is There Evidence for a Bidimensional Organization of Symptoms?

“…Comorbidity did not have a great impact on the number of classes, type of symptoms included, and level of endorsement in each class in different studies (Acosta et al, 2008;Neuman et al, 2001;Volk et al, 2006;Volk et al, 2005). The same applied for different information source (Althoff et al, 2006).…”

“…Our literature review was able to identify 14 studies that used LCA to describe the structure of ADHD symptoms in a given population (Acosta et al, 2008;Althoff et al, 2006;Hudziak et al, 1998;Lubke et al, 2007;Neuman et al, 2001;Neuman et al, 2005;Neuman et al, 1999;Rohde ADHD ACROSS CULTURES et al, 2001;Todd et al, 2001;Volk, Henderson, Neuman, & Todd, 2006;Volk, Neuman, & Todd, 2005). As reported for factor analyses, the integration of findings is extremely difficult because investigations were conducted in samples from different age ranges, proportion of boys=girls and nationalities, using different information sources, and approaches related to the inclusion of comorbidities in analyses.…”

Simple Identification of Complex ADHD Subtypes Using Current Symptom Counts

“…As judged by Child Behavior Checklist (CBCL) criteria 12 , these subtypes are characterized by increased attention problems and social problems subscales. 13 The severe inattentive and combined subtypes are more likely to have poor grades and to have had an Individual Education Plan (school program to address specific special education needs) compared to DSM-IV and other population-defined subtypes. 14 These ADHD subtypes also have high levels of autistic symptoms and motor problems, especially the severe combined type.…”