Are sensation seeking and emotion processing related to or distinct from cognitive control in children with ADHD?

This study evaluated the relationship of (a) reactive inhibition and right-lateralized emotion processing to each other and (b) to executive control of response suppression, and (c) with regard to ADHD in 134 children ages 7-12 years. Reactive inhibition was indexed by child ratings of sensation seeking on the Sensation Seeking Scales, executive control by the Stop Signal Task, emotion processing by performance on the Chimeric Faces Test, and ADHD by parent- and teacher-reported symptoms. The results were consistent with a two-process model in which executive control, conceived as a right-hemisphere lateralized function, was distinct from sensation seeking and lateralized emotion processing. Supporting this distinction, ADHD was associated with executive control, but not with sensation seeking/reactive inhibition or lateralized emotion processing. The findings suggest that ADHD cannot be understood as a global right-lateralized neuropsychological weakness, but rather that it involves only particular functions that may be right lateralized. Findings further suggest that risk for comorbid disorders in ADHD (e.g., conduct disorder or mood disorders) may increase as a function of independent factors such as temperament. Mechanisms underlying executive inhibition and emotional processing could be functionally independent yet interact to multiply psychopathological risk in some children (leading, for example, to comorbid disorders).     

Priming Sentence Production in Adolescents and Adults with Attention-Deficit/Hyper-Activity Disorder

Theoretical accounts of attention-deficit/hyperactivity disorder (ADHD) posit a prominent role for problems in response inhibition (Nigg 2006). A key avenue for impulsivity in children with ADHD is inappropriate language expression. In this study, we sought to determine whether poor inhibitory control affects language production in adolescents and adults with ADHD. One hundred and ninety-five participants (13–35 years old; 65% male) were presented with two pictures and a verb, and their task was to form a sentence. If deficits in response inhibition affect language production, then participants with ADHD should be more likely than non-ADHD controls to begin speaking before having formulated a plan that will allow a grammatical continuation. The results showed that the ADHD-combined subtype, in particular, was more likely to produce an ungrammatical sequence. Effects were not moderated by age or gender. These data suggest that response suppression deficits in ADHD adversely affect the basic processes of sentence formation.     

Executive functions and ADHD in adults: evidence for selective effects on ADHD symptom domains

Dual-process models of attention-deficit/hyperactivity disorder (ADHD) suggest that both executive functioning and regulatory functions (e.g., processing speed) are involved and that executive function weaknesses may be associated specifically with symptoms of inattention-disorganization but not hyperactivity-impulsivity. Adults aged 18-37 (105 with ADHD, 90 controls) completed a neuropsychological battery. The ADHD group had weaker performance than did the control group (p<.01) on both executive and speed measures. Symptoms of inattention-disorganization were uniquely related to executive functioning with hyperactivity-impulsivity controlled. Inattention was associated with slower response speed, and hyperactivity-impulsivity with faster output speed. Results were not accounted for by IQ, age, gender, education level, or comorbid disorders. Findings are discussed in terms of developmental and dual-process models of ADHD leading into adulthood.     

Neuropsychological functioning,motor speed,and language processing in boys with and without ADHD

We administered a neuropsychological battery to boys aged 6 to 12 years old diagnosed with attention-deficit hyperactivity disorder (ADHD; n= 51) and to comparison boys of the same age range (n= 31). Boys with ADHD had greater difficulty than comparison youngsters on nonautomated language and motor tasks administered with a fast instructional set and on one of two traditional frontal executive measures (Porteus mazes). When tasks requiring automatic processing were paired with similar tasks requiring greater use of selective attention processes, the latter, controlled processing tasks differentiated groups better than did automated tasks. This differential effect of otherwise similar tasks is interpreted in terms of an output deficit mediated by response organization as detailed in the information processing literature. The ADHD group also exhibited slow gross motor output, measured independently of verbal output. The findings are evaluated in terms of both Luria's (1973) tripartite model of neurocognitive organization and frontal striatal models, with an emphasis on output processes. The observed language deficits could represent frontal lobe processes intricately related to self-monitoring and planning. The utility of controlled processing, self-paced tasks with fast instructional sets in assessing language and motor skills in ADHD is highlighted. This research was supported primarily by National Institute of Mental Health Grant R01 MH45064 awarded to Stephen P. Hinshaw. Joel T. Nigg was partially supported by NIH Research Service Award F31 MH10462-01. The authors wish to thank Deborah P. Waber, Ph.D., of Harvard University for her assistance in scoring the Rey-Osterreith complex design, and Jennifer Ablow, Margaret Kuklinsksi, Jeff Measelle, Teron Park, Cassandra Simmel, and Jennifer Treuting for helping to administer the measures, code the results, and discuss the study. We also acknowledge the enthusiastic participation of the children and families in the summer programs.     

Is the fluency of language outputs related to individual differences in intelligence and executive function?

There has been little research on the fluency of language production and individual difference variables, such as intelligence and executive function. In this study, we report data from 106 participants who completed a battery of standardized cognitive tasks and a sentence production task. For the sentence production task, participants were presented with two objects and a verb and their task was to formulate a sentence. Four types of disfluency were examined: filled pauses (e.g. uh, um), unfilled pauses, repetitions, and repairs. Repetitions occur when the speaker suspends articulation and then repeats the previous word/phrase, and repairs occur when the speaker suspends articulation and then starts over with a different word/phrase. Hierarchical structural equation modeling revealed a significant relationship between repair disfluencies and inhibition. Conclusions focus on the role of individual differences in cognitive ability and their role in models and theories of language production.     

The structure of childhood disruptive behaviors

Attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) frequently co-occur. Comorbidity of these 2 childhood disruptive behavior domains has not been satisfactorily explained at either a structural or etiological level. The current study evaluated a bifactor model, which allows for a "g" factor in addition to distinct component factors, in relation to other models to improve understanding of the structural relationship between ADHD and ODD. Participants were 548 children (321 boys, 227 girls) between the ages of 6 years and 18 years who participated in a comprehensive diagnostic assessment incorporating parent and teacher ratings of symptoms. Of these 548 children, 153 children were diagnosed with ADHD (without ODD), 114 children were diagnosed with ADHD + ODD, 26 children were diagnosed with ODD (without ADHD), and 239 children were classified as non-ADHD/ODD comparison children (including subthreshold cases). ADHD symptoms were assessed via parent report on a diagnostic interview and via parent and teacher report on the ADHD Rating Scale. ODD symptoms were assessed via teacher report. A bifactor model of disruptive behavior, comprising a "g" factor and the specific factors of ADHD and ODD, exhibited best fit, compared to 1-factor, 2-factor, 3-factor, and 2nd-order factor models of disruptive behaviors. It is concluded that a bifactor model of childhood disruptive behaviors is superior to existing models and may help explain common patterns of comorbidity between ADHD and ODD.     

Cognitive inhibition and working memory in attention-deficit/hyperactivity disorder

Studies of cognitive control in attention-deficit/hyperactivity disorder (ADHD) have emphasized the ability to suppress motor responses (i.e., behavioral inhibition) rather than the ability to actively suppress prepotent mental representations (i.e., cognitive inhibition). Further, working memory deficits are suspected in ADHD, yet their distinction from cognitive inhibition is unclear. Two hundred and eighty-eight adolescent and adult participants, 115 of whom met criteria for ADHD and 173 of whom were for non-ADHD comparison, completed a sentence processing task that required the suppression of an incorrect interpretation and a working memory task. The results failed to support cognitive inhibition problems in ADHD. Moreover, the ability to reanalyze sentences with a temporary misinterpretation was at least partially related to working memory performance. The results challenge a unitary inhibition problem in ADHD and suggest inhibition problems do not extend to cognitive suppression in this age range.     

External Validation of Bifactor Model of ADHD: Explaining Heterogeneity in Psychiatric Comorbidity,Cognitive Control,and Personality Trait Profiles Within DSM-IV ADHD

The current paper provides external validation of the bifactor model of ADHD by examining associations between ADHD latent factor/profile scores and external validation indices. 548 children (321 boys; 302 with ADHD), 6 to 18 years old, recruited from the community participated in a comprehensive diagnostic procedure. Mothers completed the Child Behavior Checklist, Early Adolescent Temperament Questionnaire, and California Q-Sort. Children completed the Stop and Trail-Making Task. Specific inattention was associated with depression/withdrawal, slower cognitive task performance, introversion, agreeableness, and high reactive control; specific hyperactivity-impulsivity was associated with rule-breaking/aggressive behavior, social problems, errors during set-shifting, extraversion, disagreeableness, and low reactive control. It is concluded that the bifactor model provides better explanation of heterogeneity within ADHD than DSM-IV ADHD symptom counts or subtypes.     

Is ADHD a disinhibitory disorder?

Attention deficit hyperactivity disorder (ADHD) is widely theorized to stem from dysfunctional inhibitory processes. However, the definition of inhibition is imprecisely distinguished across theories. To clarify the evidence for this conception, the author relies on a heuristic distinction between inhibition that is under executive control and inhibition that is under motivational control (anxiety or fear). It is argued that ADHD is unlikely to be due to a motivational inhibitory control deficit, although suggestions are made for additional studies that could overturn that conclusion. Evidence for a deficit in an executive motor inhibition process for the ADHD combined type is more compelling but is not equally strong for all forms of executive inhibitory control. Remaining issues include specificity to ADHD, whether inhibitory problems are primary or secondary in causing ADHD, role of comorbid anxiety and conduct disorder, and functional deficits in the inattentive ADHD subtype.     

Working Memory Mediates Increased Negative Affect and Suicidal Ideation in Childhood Attention-Deficit/Hyperactivity Disorder

Children with attention-deficit/hyperactivity disorder (ADHD) are at greater risk for suicidal ideation and suicide attempts compared to those without ADHD. Increased risk is at least partially attributable to a subset of children with ADHD and comorbid depression or disruptive behavior disorders; however, the early predictors and mechanisms driving increased risk are not well understood. Here, we investigate the contributions of two candidate mechanisms for increased suicidal ideation in children with ADHD: executive function and negative affect. 623 clinically well-characterized, community-recruited children classified by research criteria as ADHD (n = 388) or typically-developing controls (n = 253) participated. Parent-report on the Temperament in Middle Childhood Questionnaire provided a measure of negative affectivity. Children completed laboratory tasks to measure response inhibition and working memory. Suicidal ideation was evaluated by parent report during a semi-structured interview and child responses on the Children’s Depression Inventory. Compared to typically developing controls, children with ADHD had higher rates of suicidal ideation, more negative affect, slower stop signal reaction times, and weaker working memory. Statistical path-model analyses confirmed the hypothesis that weaker working memory in ADHD statistically mediated increased negative affect. Weaker working memory also mediated and increased suicidal ideation in these cross sectional data. Findings were not attributable to comorbid disruptive behavioral disorders. Poor response inhibition did not reliably mediate negative affect or suicidal ideation. Impairment in working memory is an important early risk factor for suicidal ideation in children with ADHD, and may help in identifying children for prevention and early intervention efforts.