The Genetic Association Between ADHD Symptoms and Reading Difficulties: The Role of Inattentiveness and IQ

Previous studies have documented the primarily genetic aetiology for the stronger phenotypic covariance between reading disability and ADHD inattention symptoms, compared to hyperactivity-impulsivity symptoms. In this study, we examined to what extent this covariation could be attributed to “generalist genes” shared with general cognitive ability or to “specialist” genes which may specifically underlie processes linking inattention symptoms and reading difficulties. We used multivariate structural equation modeling on IQ, parent and teacher ADHD ratings and parent ratings on reading difficulties from a general population sample of 1312 twins aged 7.9–10.9 years. The covariance between reading difficulties and ADHD inattention symptoms was largely driven by genetic (45%) and child-specific environment (21%) factors not shared with IQ and hyperactivity-impulsivity; only 11% of the covariance was due to genetic effects common with IQ. Aetiological influences shared among all phenotypes explained 47% of the variance in reading difficulties. The current study, using a general population sample, extends previous findings by showing, first, that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genes contributing to general cognitive ability and, second, that child-specific environment factors, independent from IQ, also contribute to the covariation between reading difficulties and inattention symptoms.     

The Separation of ADHD Inattention and Hyperactivity-Impulsivity Symptoms: Pathways from Genetic Effects to Cognitive Impairments and Symptoms

Both shared and unique genetic risk factors underlie the two symptom domains of attention deficit hyperactivity disorder (ADHD): inattention and hyperactivity-impulsivity. The developmental course and relationship to co-occurring disorders differs across the two symptom domains, highlighting the importance of their partially distinct etiologies. Familial cognitive impairment factors have been identified in ADHD, but whether they show specificity in relation to the two ADHD symptom domains remains poorly understood. We aimed to investigate whether different cognitive impairments are genetically linked to the ADHD symptom domains of inattention versus hyperactivity-impulsivity. We conducted multivariate genetic model fitting analyses on ADHD symptom scores and cognitive data, from go/no-go and fast tasks, collected on a population twin sample of 1,312 children aged 7–10. Reaction time variability (RTV) showed substantial genetic overlap with inattention, as observed in an additive genetic correlation of 0.64, compared to an additive genetic correlation of 0.31 with hyperactivity-impulsivity. Commission errors (CE) showed low additive genetic correlations with both hyperactivity-impulsivity and inattention (genetic correlations of 0.17 and 0.11, respectively). The additive genetic correlation between RTV and CE was also low and non-significant at ?0.10, consistent with the etiological separation between the two indices of cognitive impairments. Overall, two key cognitive impairments phenotypically associated with ADHD symptoms, captured by RTV and CE, showed different genetic relationships to the two ADHD symptom domains. The findings extend a previous model of two familial cognitive impairment factors in combined subtype ADHD by separating pathways underlying inattention and hyperactivity-impulsivity symptoms.     

The Role of Maternal and Child ADHD Symptoms in Shaping Interpersonal Relationships

The current study investigated the influence of maternal ADHD symptoms on: (a) mothers’ own social functioning; (b) their child’s social functioning; and (c) parent–child interactions following a lab-based playgroup involving children and their peers. Participants were 103 biological mothers of children ages 6–10. Approximately half of the children had ADHD, and the remainder were comparison youth. After statistical control of children’s ADHD diagnostic status and mothers’ educational attainment, mothers’ own inattentive ADHD symptoms predicted poorer self-reported social skills. Children with ADHD were reported to have more social problems by parents and teachers, as well as received fewer positive sociometric nominations from playgroup peers relative to children without ADHD. After control of child ADHD status, higher maternal inattention and hyperactivity/impulsivity each predicted children having more parent-reported social problems; maternal inattention predicted children receiving more negative sociometric nominations from playgroup peers. There were interactions between maternal ADHD symptoms and children’s ADHD diagnostic status in predicting some child behaviors and parent–child relationship measures. Specifically, maternal inattention was associated with decreased prosocial behavior for children without ADHD, but did not influence the prosocial behavior of children with ADHD. Maternal inattention was associated with mothers’ decreased corrective feedback and, at a trend level, decreased irritability toward their children with ADHD, but there was no relationship between maternal inattention and maternal behaviors for children without ADHD. A similar pattern was observed for maternal hyperactivity/impulsivity and mothers’ observed irritability towards their children. Treatment implications of findings are discussed.     

Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?

Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) with performance on the delayed oculomotor response (DOR) task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects' ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than were controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower reaction times (RTs), greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than did controls. Greater variability in RT was associated with increased distraction on the DOR task, but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD.     

Clinical,Sociobiological, and Cognitive Predictors of ADHD Persistence in Children Followed Prospectively Over Time

With increasing awareness that ADHD is chronically disabling, a burgeoning literature has examined childhood clinical indicators of ADHD persistence. This study investigates whether childhood factors reflecting biological risk and cognitive reserve have additive predictive value for the persistence of ADHD that is unique beyond childhood indicators of disorder severity. One-hundred thirty children with ADHD (mean age = 8.9 years, 75 % male) were followed into adolescence (mean age = 14.0 years). Childhood ADHD and co-morbidities were assessed via interviews with parents and teachers; parental psychopathology was assessed via parent interview; exposure to neurobiological and psychosocial adversity were indexed by parent questionnaire; and cognitive reserve was evaluated through children’s performance on measures of IQ and executive functioning. Univariate analyses identified childhood inattention and hyperactivity-impulsivity, co-morbid oppositional defiant disorder, overall impairment, and paternal anxiety and depression as more prevalent amongst adolescents with persistent compared with remitted ADHD. Only child-level predictors remained significant in a final multivariate model. These results suggest that children who are most likely to experience persistent ADHD have a more severe clinical presentation in childhood, reflected by increased levels of inattention, oppositional behavior, and impairment. They also are more likely to have fathers with internalizing concerns, but these concerns do not uniquely predict ADHD persistence beyond child-level factors. Contrary to expectations, childhood adversity and cognitive functioning did not predict the course of ADHD.     

The relationship of compliance with inattention and hyperactivity/impulsivity

The aim of the study was to investigate the relationship between Attention Deficit Hyperactivity Disorder (ADHD) inattention and hyperactivity/impulsivity symptoms in predicting compliance. It was hypothesised that inattention symptoms are a better predictor of compliance than hyperactivity/impulsivity. There were two different groups of participants: 367 college students (both males and females) and 89 male prisoners. All participants had completed the Gudjonsson Compliance Scale (GCS) and the DSM-IV-TR (Screening) Checklist for adult ADHD symptoms. Significant correlations emerged between compliance and ADHD symptoms, but the correlations were higher for inattention than hyperactivity/impulsivity among both samples. This was confirmed by multiple regression analyses (hierarchical), which showed that the variance in compliance explained by ADHD inattention versus hyperactivity/impulsivity symptoms increased from 2% to 8% for college students and 8% to 24% for prisoners after entering inattention into the model (hyperactivity/impulsivity was entered first in the regression models). The findings suggest that inattention is a more powerful predictor of compliance than hyperactivity/impulsivity. This is a novel and an important finding.     

Antisocial behavior reduces the association between subdimensions of ADHD symptoms and alcohol use in a large population‐based sample of adolescents

The aim of this study was to investigate possible effects of antisocial behavior on reducing the association between subdimensions of ADHD symptoms (inattention, hyperactivity and impulsivity) and alcohol use. Boys and girls were analyzed separately using a population‐based Swedish adolescent sample. A randomly selected cross‐sectional survey was performed in secondary and upper secondary schools in Västmanland County during 2010. Participants were a population of 2,439 15–16 year‐olds and 1,425 17–18 year‐olds (1,947 girls and 1,917 boys). Psychosocial adversity, antisocial behaviors, symptoms of ADHD and alcohol use were assessed by questionnaires. Except for girls' inattention, subdimensions of ADHD symptoms were not associated with alcohol use when variance due to antisocial behavior was accounted for. Among boys, instead of an indirect effect of antisocial behavior on the association between impulsivity and alcohol use, a moderating effect was found. Among girls, the inattention component of ADHD was independently associated with alcohol use even when adjusted for antisocial behavior. The reduced associations between symptoms of hyperactivity, impulsivity, and alcohol use for boys and girls after adjusting for antisocial behavior suggest a considerable overlap between hyperactivity, impulsivity, and antisocial behavior. The direct pathway between inattention and alcohol use among girls suggests that girls with inattention symptoms are at risk of alcohol use regardless of antisocial behavior. Special attention should be given to these girls. Accounting for antisocial behavior reduced the relation between subdimensions of ADHD symptoms and alcohol use, and antisocial behaviors should therefore be screened for when symptoms of ADHD are present.     

Confirming the Factor Structure of Attention Deficit Hyperactivity Disorder Symptoms in Adult, Nonclinical Samples

Three separate models have been proposed to describe the factor structure of attention deficit hyperactivity disorder (ADHD) in the past 20 years. The Diagnostic and Statistical Manual of Mental Disorders-III (DSM-III, 1980) proposed 3 separate factors of inattention, hyperactivity, and impulsivity. The DSM-III-R (1987) proposed a single factor. The DSM-IV (1994) described the disorder as having 2 factors: hyperactivity/impulsivity and inattention. The following 2 studies employed confirmatory factor analysis to compare each of these models and 3 alternative models. University students completed questionnaires that assessed each of the 18 symptoms listed in the DSM-IV for ADHD. The 3-factor model fit the data significantly better than each of the other models in both studies. These findings suggest that a 3-factor model of inattention, hyperactivity, and impulsivity describes adult ADHD symptoms better than current alternatives.     

Attention-Deficit/Hyperactivity Disorder Symptoms in Mothers and Fathers: Family Level Interactions in Relation to Parenting

Previous studies linking parent ADHD symptoms to parenting have typically focused on each parent individually. To provide a broader understanding of family context, in this study, levels of inattention and hyperactivity-impulsivity in mothers and fathers were examined, both individually and in combination, in relation to negative parenting and child-rearing disagreements. Two-parent families of 5 to 13 year old boys (126 with ADHD and 53 typically developing) participated. Parents reported their own ADHD symptoms and their perceptions of child-rearing disagreements. Parenting was measured using self-, partner-, and child-reports as well as observations. Controlling for child ADHD symptoms, inattention symptoms in fathers predicted parenting difficulties. For mothers, inattention symptoms were linked to parenting problems only when fathers also had high levels of inattention. In contrast, parenting was most problematic for both mothers and fathers in families in which fathers had higher and mothers had lower levels hyperactivity-impulsivity symptoms. These results remained essentially unchanged when child externalizing behavior and mother depression and hostility were controlled, but father depression reduced the significance of some interactions. The results highlight the importance of the match between father and mother levels of symptoms, and point to differential relations of parenting to inattention and hyperactivity-impulsivity symptoms in parents.     

Parental Cognitive Errors Mediate Parental Psychopathology and Ratings of Child Inattention

We investigate the Depression‐Distortion Hypothesis in a sample of 199 school‐aged children with ADHD‐Predominantly Inattentive presentation (ADHD‐I) by examining relations and cross‐sectional mediational pathways between parental characteristics (i.e., levels of parental depressive and ADHD symptoms) and parental ratings of child problem behavior (inattention, sluggish cognitive tempo, and functional impairment) via parental cognitive errors. Results demonstrated a positive association between parental factors and parental ratings of inattention, as well as a mediational pathway between parental depressive and ADHD symptoms and parental ratings of inattention via parental cognitive errors. Specifically, higher levels of parental depressive and ADHD symptoms predicted higher levels of cognitive errors, which in turn predicted higher parental ratings of inattention. Findings provide evidence for core tenets of the Depression‐Distortion Hypothesis, which state that parents with high rates of psychopathology hold negative schemas for their child's behavior and subsequently, report their child's behavior as more severe.     

Familial Aggregation of ADHD Characteristics

Patterns of familial aggregation of ADHD symptoms in parents of ADHD and non-ADHD children were examined. Within the ADHD sample, symptom aggregation was examined as a function of biological relationship, parent and child gender, and children's comorbid diagnoses. Participants consisted of parents of 579 children with ADHD, Combined Type participating in the multimodal treatment study of children with ADHD and parents of 288 normal control participants. Adult symptoms of ADHD were measured by both self-report and report of a significant other. Results indicated that the parents of children with ADHD had higher ratings of inattention/cognitive problems, hyperactivity/restlessness, impulsivity/emotional lability, and lower self-concept than parents of children without ADHD on both self-report and other-report ratings. Within the ADHD sample of children, other-report ratings of inattention/cognitive problems and impulsivity/emotional lability were higher for biological parents compared to nonbiological parents whereas self-ratings were not related to biological status. These findings support previous research documenting familial aggregation of ADHD and appear to strengthen the hypothesis that there is a genetic contribution to ADHD.     

The Factor Structure of ADHD – Different Models,Analyses and Informants in a Bifactor Framework

The methodological approach of exploratory structural equation modelling (ESEM) has only been applied once to the construct of Attention-deficit/hyperactivity disorder (ADHD). We decided to compare bifactor models based on confirmatory factor analyses (Bi-CFA) and exploratory equation modeling (Bi-ESEM) only, as there is a growing support of a bifactor structure of ADHD. To examine the factorial validity of the construct we compared three possible bifactor models. One model with two specific factors (inattention and hyperactivity/impulsivity), another model with three specific factors (inattention, hyperactivity and impulsivity) and an alternative, incomplete model with one general ADHD and two specific factors (inattention and impulsivity). We used parent- (N = 1386; Age: M = 11.70, SD = 3.18; Sex: 74.5 % male) and teacher-ratings (N = 110; Age: M = 11.27, SD = 3.04; Sex: 77.5 % male) from clinically referred children between the age of 6 and 18. The results indicate that both methods lead to equally good model fit and for both informants the reliable variance of the specific factor hyperactivity is almost completely explained by the general factor. However, in the teacher condition cross-loadings seem to be of particular importance. Across both methods and informants covariation among ADHD symptom items can be in most part attributed to a general ADHD factor as well as to three (inattention, hyperactivity and impulsivity) or two (inattention and impulsivity) weakly defined specific factors. Further research regarding associations between the specific factors of ADHD and other disorders (e.g. conduct disorder) should be conducted.     

Which components of processing speed are affected in ADHD subtypes?

The term “processing speed” (PS) encompasses many components including perceptual, cognitive and output speed. Despite evidence for reduced PS in Attention-Deficit/Hyperactivity Disorder (ADHD), little is known about which component(s) is most impacted in ADHD, or how it may vary by subtypes. Participants included 151 children, ages 8–12 years, with ADHD Predominantly Inattentive Type, ADHD Combined Type and typically developing controls using DSM-IV criteria. All children completed four measures of processing speed: Symbol Search, Coding, Decision Speed, and simple reaction time. We found children with ADHD-PI and ADHD-C had slower perceptual and psychomotor/incidental learning speed than controls and that ADHD-PI had slower decision speed than controls. The subtypes did not differ on any of these measures. Mean reaction time was intact in ADHD. Hence, at a very basic output level, children with ADHD do not have impaired speed overall, but as task demands increase their processing speed becomes less efficient than controls’. Further, perceptual and psychomotor speed were related to inattention, and psychomotor speed/incidental learning was related to hyperactivity/impulsivity. Thus, inattention may contribute to less efficient performance and worse attention to detail on tasks with a higher perceptual and/or psychomotor load; whereas hyperactivity/impulsivity may affect psychomotor speed/incidental learning, possibly via greater inaccuracy and/or reduced learning efficiency. Decision speed was not related to either dimension. Results suggest that PS deficits are primarily linked to the inattention dimension of ADHD but not exclusively. Findings also suggest PS is not a singular process but rather a multifaceted system that is differentially impacted in ADHD.     

Inattentive and noninattentive ADHD children: Do they constitute a unitary group?

Teacher-rated ADHD and normal control children were administered a continuous performance test (CPT), and were then further subdivided based upon the presence or absence of objectively assessed attentional deficits. In addition, children were assessed using several measures of cognitive and behavioral functioning. Attentional deficits were signficantly more prevalent among the ADHD group, but about half of the ADHD children showed no evidence of objectively assessed attentional dysfunction. Further group analyses indicated that ADHD children with objectively assessed attentional dysfunction appeared cognitively impaired, while ADHD children without objective evidence of attentional dysfunction had more conduct problems. CPT inattention was not related to the presence of cognitive impairments or conduct problems in the control group. These data must be considered preliminary because teacher ratings were the only source of diagnosis and a single measure of inattention was used. However, they suggest that two subtypes of ADHD children can be identified, one characterized by inattention and learning problems, and the other by conduct problems.The authors gratefully acknowledge the assistance of Sister Hildegard Kogler and the St. Francis DeSales School, and the parents and children who participated in this study.     

The Relation Between Sluggish Cognitive Tempo and DSM-IV ADHD

To test the relation between sluggish cognitive tempo (SCT) and DSM-IV ADHD symptoms, parent and teacher ratings of the 18 DSM-IV ADHD items and five potential SCT items were obtained in a community sample of 8-18 year-old twins that was overselected for ADHD and learning disabilities (n = 296). Confirmatory factor analyses revealed that a three-factor model provided the best fit to the data for both parent and teacher ratings. DSM-IV inattention and hyperactivity-impulsivity symptoms loaded on two factors consistent with the DSM-IV model, and five SCT symptoms loaded primarily on a third factor. The SCT and inattention factors were highly correlated, whereas SCT and hyperactivity-impulsivity were weakly related. Both raters indicated that children meeting symptom criteria for the combined and inattentive subtypes exhibited significantly more SCT symptoms than those meeting symptom criteria for hyperactive-impulsive type and the comparison group without ADHD. Children meeting symptom criteria for the inattentive type exhibited significantly more SCT symptoms than those meeting criteria for the combined type, based on teacher ratings. These results suggest that SCT is an internally consistent construct that is significantly associated with DSM-IV inattention.     

成人注意缺陷多动障碍诊断与心理治疗的研究进展

注意缺陷多动障碍（ADHD）是指一种以注意缺陷、多动、冲动的行为表现为主要特征的精神病理障碍。对儿童注意缺陷多动障碍的研究有了长足的进步,但对成人注意缺陷多动障碍的研究相对较少。本文阐明了国际上对成人注意缺陷多动障碍的诊断与心理治疗的研究进展,希望引起国内临床心理学家、精神病学家和心理咨询师等的充分重视。     

Etiology of Inattention and Hyperactivity/Impulsivity in a Community Sample of Twins with Learning Difficulties

A community sample of 373 8 to 18 year-old twin pairs in which at least one twin in each pair exhibited a history of learning difficulties was utilized to examine the etiology of inattention and hyperactivity/impulsivity (hyp/imp). Symptoms of attention-deficit/hyperactivity disorder (ADHD) were assessed by the DSM-III Diagnostic Interview for Children and Adolescents. Inattention and hyp/imp composite scores were created based on results of a factor analysis. Results indicated that extreme ADHD scores were almost entirely attributable to genetic influences across several increasingly extreme diagnostic cutoff scores. Extreme inattention scores were also highly heritable whether or not the proband exhibited extreme hyp/imp. In contrast, the heritability of extreme hyp/imp increased as a linear function of the number of inattention symptoms exhibited by the proband. This finding suggests that extreme hyp/imp may be attributable to different etiological influences in individuals with and without extreme inattention. If this result can be replicated in other samples, it would provide evidence that the hyp/imp symptoms exhibited by individuals with Combined Type ADHD and Predominantly Hyp/Imp Type ADHD may be attributable to different etiological influences.     

Inattention,working memory,and academic achievement in adolescents referred for attention deficit/hyperactivity disorder (ADHD)

This study investigated the role of inattention and working memory in predicting academic achievement in 145 adolescents aged 13 to 18 referred for attention deficit/hyperactivity disorder (ADHD). Path analysis was used to examine whether auditory-verbal and visual-spatial working memory would mediate the relationships between classroom inattention symptoms and achievement outcomes. Results provide support for the mediational model. Behavioral inattention significantly predicted both auditory-verbal and visual-spatial working memory performance. Auditory-verbal working memory was strongly associated with adolescents' achievement in reading and mathematics, while visual-spatial working memory was only associated with achievement in mathematics. The path from inattention symptoms to reading was partially mediated by the working memory variables, but the path from inattention to mathematics was not mediated by working memory. The proposed model demonstrated a good fit to the data and explained a substantial amount of variance in the adolescents' achievement outcomes. These findings imply that working memory is a risk factor for academic failure for adolescents with attentional problems.     

DSM-IV-Defined Inattention and Sluggish Cognitive Tempo: Independent and Interactive Relations to Neuropsychological Factors and Comorbidity

The aim of the present study was to investigate the independent relations of DSM-IV-defined inattention and behaviors characteristic of sluggish cognitive tempo (SCT) to neuropsychological factors and problem behaviors often comorbid with attention deficit/hyperactivity disorder (ADHD). By controlling for symptoms of DSM-IV-defined inattention, unique relations to SCT could be ascertained. Additionally, interactive relations of DSM-IV-defined inattention and SCT were of interest. A community-based sample of school children (N = 209; the higher end of the ADHD-symptom range was oversampled) completed neuropsychological tasks designed to measure executive function (EF), sustained attention, and state regulation. Behavioral symptoms were measured using parental and teacher ratings of the DSM-IV criteria for ADHD and Oppositional Defiant Disorder (ODD). The results showed that these two domains of inattention, DSM-IV-defined inattention and SCT, have neuropsychological processes and comorbid behavioral problems in common. However, when controlling for the overlap, DSM-IV-defined inattention was uniquely related to EF and state regulation, while SCT was uniquely related to sustained attention. In addition, the results showed an interactive relation of DSM-IV-defined inattention and SCT to ODD. Findings from the present study support the notion that DSM-IV-defined inattention constitutes a somewhat heterogeneous condition. Such results can further our theoretical understanding of the neuropsychological impairments and comorbid behavioral problems associated with ADHD symptoms.