Validity of the executive function theory of attention-deficit/hyperactivity disorder: a meta-analytic review.

Attention-deficit hyperactivity disorder (ADHD) is a disorder of inattention, impulsivity, and hyperactivity that affects 8-12% of children worldwide. Although the rate of ADHD falls with age, at least half of children with the disorder will have impairing symptoms in adulthood. Twin, adoption, and molecular genetic studies show ADHD to be highly heritable, and other findings have recorded obstetric complications and psychosocial adversity as predisposing risk factors. Converging evidence from animal and human studies implicates the dysregulation of frontal-subcortical-cerebellar catecholaminergic circuits in the pathophysiology of ADHD, and molecular imaging studies suggest that abnormalities of the dopamine transporter lead to impaired neurotransmission. Studies during the past decade have shown the safety and effectiveness of new non-stimulant drugs and long-acting formulations of methylphenidate and amfetamine. Other investigations have also clarified the appropriate role of targeted psychosocial treatments in the context of ongoing pharmacotherapy.

SeminarAttention-deficit hyperactivity disorder

Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses, updating working memory representations, and shifting between task sets), measured as latent variables, examined why people vary in these executive control abilities and why these abilities are correlated but separable from a behavioral genetic perspective. Results indicated that executive functions are correlated because they are influenced by a highly heritable (99%) common factor that goes beyond general intelligence or perceptual speed, and they are separable because of additional genetic influences unique to particular executive functions. This combination of general and specific genetic influences places executive functions among the most heritable psychological traits. These results highlight the potential of genetic approaches for uncovering the biological underpinnings of executive functions and suggest a need for examining multiple types of executive functions to distinguish different levels of genetic influences.

Individual differences in executive functions are almost entirely genetic in origin

Socioeconomic inequalities and mental health problems in children and adolescents: A systematic review

This review discusses conceptual issues in relating temperament to psychopathology, including the disputed relation of temperament to personality in children. A potential integrative framework is discussed that links trait and biological markers of temperament (reactive, incentive-response tendencies) with regulatory processes. This framework is utilized to highlight potential temperamental pathways to specific forms of psychopathology, noting that in some instances their relations may reflect a spectrum model (with psychopathology closely related as an extreme of a temperament-based trait), but in many instances it likely reflects a vulnerability-transaction set of processes. Conduct disorder involves at least two temperamental paths, one emanating from low fear response and one from either high incentive approach or high anger reactivity. Attention deficit hyperactivity disorder also involves at least two temperament pathways, one involving extremely low effortful control and the other likely involving strong approach. Anxiety disorders appear to result from the confluence of high negative emotionality and low effortful control. Hypotheses for future research are presented and limitations discussed.

Temperament and developmental psychopathology

Objective This study evaluated the relationship between a family adversity index and DSM-IV attention-deficit/hyperactivity disorder (ADHD) subtypes and associated behavior problems The relationship of family adversity to symptoms and subtypes of ADHD was examined Method Parents and 206 children aged 7-13 completed diagnostic interviews and rating scales about socioeconomic status, parental lifetime psychiatric disorders, marital conflict, and stressful life events Results Children with ADHD combined type experienced more risk factors than community controls ( p = 002) or children with ADHD predominantly inattentive type ( p = 02) The families of children with ADHD combined type described more risk factors associated with family adversity than the families of children with ADHD inattentive type and the control group Parent-rated symptoms of child inattention/disorganization were related uniquely to the adversity index score independently of conduct disorder symptoms Children's perceptions of marital conflict were independently related to inattention and hyperactivity behaviors as rated by parents and teachers after control of all other risk factors Oppositional defiant symptoms were independently related to marital conflict and maternal psychopathology, whereas conduct disorder symptoms were uniquely related to low socioeconomic status and maternal psychopathology Conclusions Family adversity is related to ADHD combined type in children and may be related specifically to ADHD symptoms in addition to conduct disorder symptoms

Family Adversity in DSM-IV ADHD Combined and Inattentive Subtypes and Associated Disruptive Behavior Problems

Neurogenetic models predict neuropsychological weaknesses in the relatives of children with attention-deficit/ hyperactivity disorder (ADHD). The authors examined executive and regulatory measures in 386 relatives (307 parents, 79 siblings) of children with ADHD combined type, ADHD inattentive type, and controls. Predicted deficits were seen on trailmaking (relatives of ADHD combined type only), stop-signal reaction times (relatives of girls only), and response variability (mothers only) but not on naming or output speed. Effects generally held, even with relatives' ADHD status controlled. A neuropsychologically impaired subgroup of children with ADHD had relatives with clear neuropsychological weaknesses. The authors conclude that a neurogenetic model of ADHD etiology is supportable only for a subset of executive functions and that neuropsychological heterogeneity warrants more examination in ADHD.

https://psycnet.apa.org/journals/abn/113/4/614.pdf

Evaluating the endophenotype model of ADHD neuropsychological deficit: results for parents and siblings of children with ADHD combined and inattentive subtypes.

Background: A key issue in the nosology of attention deficit hyperactivity disorder (ADHD) has concerned whether the DSM-IV combined (ADHD-C) and primarily inattentive (ADHD-PI) subtypes are in fact distinct disorders, or instead are fairly closely related, perhaps differing only in severity. Pertinent to this question, but in short supply, are data on family psychiatric history.



Method:  We present new data followed by a meta-analysis. For the new data 210 children were well-characterized via structured interview and multi-informant ratings as ADHD-C or ADHD-PI. Three hundred and thirty-five parents completed structured diagnostic interviews to determine whether they had ADHD-C or ADHD-PI. Comorbid disorders were also assessed. For the meta-analysis, 6 existing family-history data sets using DSM-IV subtypes were pooled and analyzed (total N = 4120).



Results:  The new family study found support for subtype-specific transmission, but the effect was small. Girls with ADHD-C had more severe family psychiatric histories (non-ADHD disorders in parents) than girls with ADHD-I, but this subtype effect did not occur for boys. The meta-analysis of 6 data sets implemented a model-fitting methodology. Despite inconsistent results across individual studies, the pooled data consistently suggested that (1) some degree of subtype specific transmission is occurring, (2) the effect is small, (3) non-specific (gradient) transmission also occurs, specifically in families of children with ADHD-C.



Conclusion:  The much-debated relation between these two most prevalent ADHD subtypes is best modeled via two processes transmitting in families. One process is distinct for the two syndromes, and the other is shared. We briefly suggest neuropsychological models that would account for this state of affairs and suggest future research to refine the nosology with these findings in mind.

Julie Ann Stawicki

Papers

Family Adversity in DSM-IV ADHD Combined and Inattentive Subtypes and Associated Disruptive Behavior Problems

Evaluating the endophenotype model of ADHD neuropsychological deficit: results for parents and siblings of children with ADHD combined and inattentive subtypes.

Family psychiatric history evidence on the nosological relations of DSM-IV ADHD combined and inattentive subtypes: new data and meta-analysis.