The internal and external validity of sluggish cognitive tempo and its relation with DSM-IV ADHD.

Studies of subtypes of DSM-IV attention-deficit/hyperactivity disorder (ADHD) have provided inconsistent support for the discriminant validity of the combined type (ADHD-C) and predominantly inattentive type (ADHD-I). A large sample of children and adolescents with ADHD (N = 410) and a comparison group without ADHD (N = 311) were used to test the internal and external validity of sluggish cognitive tempo (SCT), a dimension characterized by low energy and sleepy and sluggish behavior. SCT scores were then incorporated in analyses of ADHD subtypes to test whether the discriminant validity of ADHD-C and ADHD-I could be improved by including SCT symptoms as part of the criteria for ADHD-I.

Colorado Learning Difficulties Questionnaire: validation of a parent-report screening measure.

This study evaluated the internal structure and convergent and discriminant evidence for the Colorado Learning Difficulties Questionnaire (CLDQ), a 20-item parent-report rating scale that was developed to provide a brief screening measure for learning difficulties. CLDQ ratings were obtained from parents of children in 2 large community samples and 2 samples from clinics that specialize in the assessment of learning disabilities and related disorders (total N = 8,004). Exploratory and confirmatory factor analyses revealed 5 correlated but separable dimensions that were labeled reading, math, social cognition, social anxiety, and spatial difficulties.

Etiology and neuropsychology of comorbidity between RD and ADHD: the case for multiple-deficit models.

Introduction: Attention-deficit/hyperactivity disorder (ADHD) and reading disability (RD) are complex childhood disorders that frequently co-occur, but the etiology of this comorbidity remains unknown.

Method: Participants were 457 twin pairs from the Colorado Learning Disabilities Research Center (CLDRC) twin study, an ongoing study of the etiology of RD, ADHD, and related disorders. Phenotypic analyses compared groups with and without RD and ADHD on composite measures of six cognitive domains.

Neuropsychological analyses of comorbidity between reading disability and attention deficit hyperactivity disorder: in search of the common deficit.

Measures of component reading and language skills, executive functions, and processing speed were administered to groups of children with attention deficit hyperactivity disorder (ADHD; n = 113), reading disability (RD; n = 109), both RD and ADHD (n = 64), and neither RD nor ADHD (n = 151). Groups with RD exhibited pronounced deficits on all measures of component reading and language skills, as well as significant weaknesses on measures of verbal working memory, processing speed, and response inhibition. Groups with ADHD exhibited weaknesses on all response-inhibition and processing speed tasks and were impaired on some measures of component reading skills and verbal working memory.

Etiology of the comorbidity between RD and ADHD: exploration of the non-random mating hypothesis.

The present research sought to test the validity of the non-random mating hypothesis in a community sample in order to determine whether it contributes significantly to the comorbidity between attention-deficit/hyperactivity disorder (ADHD) and reading disability (RD) and to test whether the two disorders segregate independently. Data were gathered from 394 twin participants of the Colorado Learning Disabilities Research Center (CLDRC) and their biological parents. Parents were asked to complete retrospective questionnaires regarding their own ADHD and RD symptomatology as children, as well as rate their children on DSM-IV ADHD symptomatology before age 12.