Genetics of childhood disorders: XX. ADHD, Part 4: is ADHD genetically heterogeneous?
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Attention Deficit Disorder with Hyperactivity↗
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Genetics of childhood disorders: XXIV. ADHD, part 8: hyperdopaminergic mice as an animal model of ADHD.
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Animals↗
Adding mixed amphetamine salts to divalproex sodium improves ADHD symptoms in children with bipolar disorder and comorbid ADHD.
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Comment↗
Functional and psychosocial impairment in adults with undiagnosed ADHD.
BACKGROUND: Identify a group of adults with 'undiagnosed' attention deficit hyperactivity disorder (ADHD) and compare their personal and family medical histories, psychosocial profiles, functional impairment and quality of life with non-ADHD controls. Additionally, compare adults with undiagnosed and diagnosed ADHD to investigate possible reasons why the undiagnosed avoid clinical detection. METHOD: ICD-9 codes for ADHD in administrative claims records and responses to a telephone-administered adult ADHD screener [the Adult ADHD Self-Report Scale (ASRS)] were used to classify approximately 21000 members of two large managed health-care plans as 'undiagnosed' (no coded diagnosis; ASRS positive) or 'non-ADHD' controls (no coded diagnosis; ASRS negative). Patients identified as 'undiagnosed' ADHD were compared with samples of non-ADHD controls and 'diagnosed' ADHD patients (ICD-9 coded ADHD diagnoses) on the basis of demographics, socio-economic status, past and present mental health conditions, and self-reported functional and psychosocial impairment and quality of life. RESULTS: A total of 752 'undiagnosed' ADHD subjects, 199 'non-ADHD' controls and 198 'diagnosed' ADHD subjects completed a telephone interview. Overall, the 'undiagnosed' ADHD cohort demonstrated higher rates of co-morbid illness and greater functional impairment than 'non-ADHD' controls, including significantly higher rates of current depression, and problem drinking, lower educational attainment, and greater emotional and interpersonal difficulties. 'Undiagnosed' ADHD subjects reported a different racial composition and lower educational attainment than 'diagnosed' ADHD subjects. CONCLUSION: Individuals with 'undiagnosed' ADHD manifest significantly greater functional and psychosocial impairment than those screening negative for the disorder, suggesting that ADHD poses a serious burden to adults even when clinically unrecognized.
Adult↗
Moment-to-moment dynamics of ADHD behaviour in South African children.
BACKGROUND: The behaviour of children with Attention-Deficit/Hyperactivity Disorder is characterized by low predictability of responding. Low behavioural predictability is one way of operationalizing intra-individual ADHD-related variability. ADHD-related variability may be caused by inefficient behavioural selection mechanisms linked to reinforcement and extinction, as suggested by the recently published dynamic developmental theory (DDT) of ADHD. DDT argues that ADHD is a basic neurobehavioural disorder, caused by dysfunctioning dopamine systems. For establishing ADHD as a neurobehavioural disorder, findings from studies conducted in Western countries should be replicated in other cultural populations. The present study replicated the study conducted in Norway, with children from the Limpopo province in the Republic of South Africa. METHODS: Boys and girls, aged 6-9 yr, from seven ethnic groups participated. Scores by teachers on the Disruptive Behavior Disorders rating scale defined participation in either ADHD-hyperactive/impulsive (-HI), ADHD-predominantly inattentive (-PI), or ADHD-combined (-C) groups. Children below the 86th percentile were matched on gender and age and comprised the non-ADHD group. The children completed a computerized game-like task where mouse clicks on one of two squares on the screen resulted in delivery of a reinforcer according to a variable interval schedule of reinforcement. Reinforcers were cartoon pictures presented on the screen together with a sound. Predictability of response location and timing were measured in terms of explained variance. RESULTS: Overall, the results replicated findings from Norway. Specifically, the ADHD-C group showed significantly lower predictability of responding than the non-ADHD group, while the ADHD-HI and the ADHD-PI groups were in-between. In accordance with the previous study, response location, but not response timing, was a sensitive behavioural measure. There were no significant gender differences. Cartoon pictures were effective reinforcers as the non-ADHD group showed learning of the task. There was no relation between behavioural predictability and motor functions. CONCLUSION: The present study makes a strong case for ADHD as a basic, neurobehavioural disorder, not a cultural phenomenon, by replicating findings from a wealthy Western country in a poor province of a developing country. The results were, generally, in line with predictions from the dynamic developmental theory of ADHD by indicating that reinforcers were less efficient in the ADHD group than in the non-ADHD group. Finally, the results substantiated ADHD-related variability as an etiologically important characteristic of ADHD behaviour.
Journal Article↗
[Symptom variations in ADHD: importance of context, development and comorbidity].
Attention-deficit hyperactivity (ADHD) is a common disorder in school-aged children and is associated with significant impairment in social and academic functioning. Its recognition is based on congruent information from different sources, because most ADHD children and adolescents are not completely aware of impairments caused by inattention and/or hyperactivity/impulsivity. Fluctuations in symptom expression may complicate the diagnosis: during clinical examination or tests sessions, ADHD symptoms may be less severe than usual or completely absent. This review examines variations in ADHD symptoms due to environmental context, internal state, circadian factors, development, psychiatric comorbidity and discusses their clinical relevance. Generally, ADHD symptoms are pervasive and identified in different areas of functioning. Despite their chronicity, they show a relative context-dependency. An unfamiliar environment or situation may lessen symptoms. The same happens in dual relations or in calm settings, when the child receives attention and positive reinforcement from the adult. On the contrary, the classroom situation with its high stimulation level (noise, visual distractors, large class size) is likely to reveal or accentuate instability, impulsivity and inattention. Independently from objective symptom fluctuations, the impact of ADHD symptoms, and their consequences on self-esteem may also vary with the degree of environmental mismatch. Recent research in experimental psychology also draws attention to the motivational state of ADHD children: preference for immediate gratification and delay aversion may explain why most of them show satisfactory attentional capacities in certain activities (for instance video games or TV), while showing impairment in school work or in other effortful tasks. The diagnosis of the full ADHD syndrome requires significant impact on functioning in at least two areas. Some children with "situational" ADHD are impaired either in school setting or exclusively at home. Manuzza et al. report long-term outcome of "situational" versus "pervasive" ADHD. School-ADHD, in opposition to home-ADHD shows similarities with the full blown syndrome, as regards proportion of anti-social personality disorder, psycho-social functioning and academic/professional achievements. Moderate seasonal variations have also been identified with less ADHD symptoms in August. This result is likely to reflect a better fit between individual characteristics and environmental demands during school holidays rather than neurobiological changes, as there are no convincing arguments for seasonal fluctuations of serotoninergic tone in ADHD. Another cause for variations in ADHD symptom expression may be the co-occurrence of a mood disorder. Relationships between early-onset mania and ADHD are discussed. The appropriate definition of prepubertal mania is still in debate; its recognition is hindered by symptom overlap and high level of comorbid conditions. Chronic emotional dysregulation with irritability and frequent temper tantrums, sometimes viewed as characteristics of early-onset mania, might reflect a--possibly severe--sub-type of ADHD rather than a prodrome of bipolarity. A marked cyclicity of symptoms, with periodic accentuation of ADHD and mood symptoms, requires careful monitoring and systematic analysis of comorbid conditions. Clarification of the complex interrelations between ADHD and bipolar disorder will be obtained from long-term studies.
Attention Deficit Disorder with Hyperactivity↗
Response to cocaine, alone and in combination with methylphenidate, in cocaine abusers with ADHD.
Attention deficit hyperactivity disorder (ADHD) is prevalent in adult cocaine abusers. Yet, it remains to be determined how the response to cocaine differs in cocaine abusers with ADHD compared to cocaine abusers without ADHD. Further, since ADHD is commonly treated with stimulants, such as methylphenidate (MPH), it is important to examine whether MPH maintenance alters the response to cocaine in cocaine abusers with ADHD. Thus, the first phase of this study compared the response to cocaine in adult cocaine abusers with ADHD to those without ADHD. The second phase assessed the effects of oral sustained-release methylphenidate (MPH-SR) maintenance (40 and 60 mg) on the response to cocaine only in those with ADHD. Cocaine abusers with ADHD (N=7) and without ADHD (N=7) who were not seeking treatment remained inpatient initially for 1 week, when the effects of cocaine alone were tested (Phase 1). Cocaine abusers with ADHD remained inpatient for an additional 3 weeks, during which the effects of cocaine during oral MPH-SR maintenance were tested (Phase 2). During cocaine fixed dosing sessions, participants received four injections of i.v. cocaine (0, 16 or 48 mg/70 kg), spaced 14 min apart. During cocaine choice sessions, participants had a choice between receiving i.v. cocaine (16 or 48 mg/70 kg) or two tokens, each exchangeable for 2 US dollars. Subjective effects related to ADHD symptoms (e.g. ratings of "Able to Concentrate") were significantly lower in cocaine abusers with ADHD compared to those without ADHD when placebo cocaine was administered. Active cocaine produced similar increases in cardiovascular and positive subjective effects in both groups and there was no difference in cocaine choice between the two groups. These data suggest that the response to cocaine is not different between cocaine abusers with ADHD compared to those without ADHD. When the cocaine abusers with ADHD were maintained on MPH-SR, cardiovascular effects were increased, however, this did not warrant termination of any test session. Maintenance on MPH-SR decreased some of the positive subjective effects of cocaine. Further, maintenance on a high dose of MPH-SR decreased cocaine choice. Thus, oral MPH-SR is safe in combination with repeated cocaine doses and decreases some of the positive and reinforcing effects of cocaine in cocaine abusers with ADHD.
Administration, Oral↗
Fine and gross motor ability in males with ADHD.
In the this study, both fine and gross motor ability of males with attention-deficit-hyperactivity disorder (ADHD) were compared with a group of control children. Three groups of males with the following ADHD subtypes: predominantly inattentive (ADHD-PI; n = 50), hyperactive/impulsive (ADHD-HI; n = 16), or combined (ADHD-C; n = 38) were compared with 39 control males. Mean ages for the control group were 10 years 4 months (SD 1 year 4 months, range 7 years 8 months to 12 years 11 months); for the ADHD-PI group, 10 years (SD 1 year 2 months, range 7 years 10 months to 13 years); for the ADHD-HI group, 9 years 11 months (SD 1 year 2 months), range 7 years 11 months to 12 years 6 months); and for the ADHD-C group 10 years 2 months (SD 1 year 4 months, range 8 to 13 years). The Australian Disruptive Behaviours Scale and Connors' Parent Rating Scale-Revised were used to assess ADHD symptomatology. Verbal IQ was estimated using two verbal subtests of the Wechsler Intelligence Scale for Children, and movement ability was assessed using the Movement Assessment Battery for Children (MABC) and the Purdue Pegboard test. Findings demonstrated that the children with ADHD had significantly poorer movement ability than control children. A high percentage of these children displayed movement difficulties consistent with developmental coordination disorder (DCD). In addition, the current study found that the type and degree of movement difficulty differed between subtypes. The Total Impairment score, as derived from the MABC, was less severe for the ADHD-HI group than the other two ADHD groups, but more severe than for the control group. Males with ADHD-PI and ADHD-C had significantly poorer fine motor ability (p < 0.001) than control males, whereas the ADHD-HI group did not differ significantly from any of the other groups. As children with ADHD only and the control group did not differ significantly on fine motor ability but were significantly better than children categorized with both ADHD and DCD, it was argued that poorer fine motor ability found in children with ADHD could not be attributed to deficits in attention and concentration, but rather to factors relating to their motor ability.
Adolescent↗
[Atomoxetine: a new treatment for Attention Deficit/Hyperactivity Disorder (ADHD) in children and adolescents].
This paper provides a review of safety and efficacy data as well as of pharmacological characteristics of atomoxetine, a new drug treatment for the Attention Deficit/Hyperactivity Disorder (ADHD). To date, the only pharmacological treatment available in France for children and adolescents diagnosed with ADHD is methylphenidate, a psychostimulant drug. However, the clinical response to methylphenidate may be absent or insufficient in about 20-30% drug-treated children while the occurrence of adverse effects with methylphenidate (sleep disturbances, loss of appetite, tics increase...) may sometimes require a dose reduction or even the discontinuation of the treatment. Atomoxetine is an alternative candidate drug for the treatment of ADHD. The drug has been developed with respect to the actual standards of investigation of drugs intended to a -pediatric use. Atomoxetine has been recently licensed in the USA for the treatment of ADHD. Atomoxetine is a potent inhibitor of the norepinephrine transporter that shows only mini-mal affinity for other neurotransmitter systems. Although pharmacokinetics of atomoxetine is influenced by the polymorphism of the CYP2D6 metabolic pathway, safety and -tolerability data reported during clinical trials did not show any difference in poor versus extensive metabolizers. In addition, atomoxetine does not inhibit nor induce the CYP2D6 enzymatic function. The major metabolite of atomoxetine is 4-hydroxyatomoxetine, a pharmacologically active metabolic found in very low plasma concentrations in pediatric patients, suggesting that it plays only a minor role in the norepinephrine reuptake inhibition. Preliminary studies were aimed to assess the effective dose range of atomoxetine and to evaluate its safety and efficacy on the reduction of ADHD symptoms in adults and children diagnosed with ADHD. Main data on the child and adolescent population were obtained in four double-blind, randomized, placebo-controlled trials: two identical pivotal trials, a multiple dose study, a once-daily dose study. The first two pivotal trials were carried out in ADHD children aged 7-13 years, treated with atomoxetine vs placebo for a duration of 9 weeks. Patients presenting comorbidities (ie conduct disorder, -anxiety, depression) as well as a history of previous treatment with methylphenidate were also eligible to participate. The primary outcome was the reduction of the score on the ADHD rating scale, ADHD-RS ; secondary criteria included the responder's rate (patients with an ADHD-RS score reduction of 25% or above), the Clinical Global Impression Scale and the Conners Parent Rating Scale. With a mean dose of 1.5 mg/kg/day, atomoxetine showed a significant reduction of mean ADHD-RS scores at endpoint (ANOVA, p<0.001) (table II). Yet, the clinical significance of both studies is limited since efficacy was scored only in a social/familial setting and not in classroom conditions. In addition, intermediate results from baseline to endpoint were not presented in the publication. The multiple dose trial showed a significant reduction of the symptom score at the 1.2 and 1.8 mg/kg/day doses. The objective of the last study was to assess the efficacy of a single daily dose of atomoxetine versus placebo during a 6 week-treatment. Patients were evaluated by parents, investigators, as well as by teachers. The superiority of atomoxetine was demonstrated as compared to the placebo and the effect size of the daily dosing was similar to that reported with multiple doses. Preliminary data on ADHD patients presenting comorbidities showed that atomoxetine alone signi-ficantly reduced the symptom scores of anxiety and depression and similarly to atomoxetine associated with fluoxetine. In ADHD children with the oppositional defiant disorder, oppositional symptoms were reduced in the group receiving atomoxetine 1.8 mg/kg/day. Preliminary results in children with ADHD and chronic tics or Tourette syndrome showed a significant reduction of ADHD symptoms and a tendency to the decrease of tics. Tolerance and safety data pooled from the child and adolescent trials were acceptable. Study discontinuations due to adverse events in the four registration studies were only 2.8%. The most frequent adverse effects reported were gastrointestinal symptoms and decreased appetite. Weight loss reported early in clinical studies tended to stabilize during the open-label extension phases lasting up to 9 months. A retrospective comparison showed that the adverse event profile of poor metabolizers was similar to that of extensive metabolizers. In summary, data presented suggest that atomoxetine is a safe and effective drug for the treatment of ADHD in children and adolescents. Further studies are expected to accurately define the place of atomoxetine in the treatment strategy of ADHD, a chronic and invalidating disorder affecting 3 to 7% of school-aged children.
Adolescent↗
The utility of self-report measures and the continuous performance test in the diagnosis of ADHD in adults.
BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) occurs in as many as 4 percent of adults yet it is often not recognized in clinical settings because the presenting symptoms may resemble those seen in other disorders or because symptoms may be masked by commonly comorbid conditions such as anxiety and depression. OBJECTIVE: The purpose of this study was to examine the diagnostic utility of instruments commonly used in the assessment of adults presenting with symptoms of ADHD. METHODS: We reviewed several widely used self-report and laboratory measures and empirically examined the utility of the Brown Attention-Deficit Disorder Scale for Adults (Brown ADD Scale) and the Conners Continuous Performance Test (CPT) in differentially identifying adults with ADHD and those with other Axis I disorders. RESULTS: Ninety-three adults who self-referred to the ADHD program for adults at a university medical center participated in the study. Of these, 44 had ADHD combined subtype (ADHD-CB), and 26 had ADHD, predominantly inattentive subtype (ADHD-IA). Thirty-three non-ADHD adults diagnosed with Axis I mood or anxiety disorders comprised an "Other Psychiatric" group. Rates of comorbid disorders, including substance abuse, in the ADHD groups were typical of those reported in the adult ADHD literature. Data on the Brown ADD Scale and on the CPT were available for subsets of 61 and 46 participants, respectively. Analyses showed that the ADHD-CB, ADHD-IA, and Other Psychiatric groups all received mean scores in the clinical range on the Brown ADD Scale, with a trend toward even higher elevations in the two ADHD groups. Among 12 CPT variables assessed for the three groups, the mean scores on only two variables for the ADHD-IA group were clinically elevated. Neither the Brown ADD Scale nor CPT scores evinced sufficient sensitivity and specificity to qualify them to assist in differential diagnosis of ADHD vis-a-vis other, predominantly internalizing, psychiatric disorders. CONCLUSION: The results indicate a need for closer examination of executive and adaptive functioning in adults with ADHD compared with those with internalizing disorders in order to identify features that could assist in differential diagnosis.
Adult↗
Differences in attention, executive functioning, and memory in children with and without ADHD after severe traumatic brain injury.
Although the development of Attention Deficit Hyperactivity Disorder (ADHD) after traumatic brain injury (TBI) has been described, it is unknown whether children with TBI and ADHD have greater neuropsychological impairments than children with TBI alone. This study examines attention, executive functioning, and memory in children with TBI-only and TBI + ADHD. Caregivers of 82 children with severe TBI completed structured psychiatric interviews at enrollment to diagnose premorbid ADHD and one-year after injury to diagnose post-injury ADHD. Children underwent neuropsychological testing one year after injury. One memory measure significantly differentiated children with TBI-only from children with newly developed ADHD [secondary ADHD (S-ADHD)] and those with premorbid ADHD that persisted after injury [persisting ADHD (P-ADHD)]. Compared with the TBI-only group, children with TBI + ADHD had worse performance on measures of attention, executive functioning, and memory. Results reveal that in children with severe TBI, the behavioral diagnosis of ADHD is associated with more difficulty in attention, executive functioning, and memory. Additionally, results suggest greater deficits in memory skills in the S-ADHD group compared with the P-ADHD group. Although findings provide preliminary support for distinguishing P-ADHD from S-ADHD, further research is needed to investigate neuropsychological differences between these subgroups of children with severe TBI.
Attention↗
ADHD comorbidity findings from the MTA study: comparing comorbid subgroups.
OBJECTIVES: Previous research has been inconclusive whether attention-deficit/hyperactivity disorder (ADHD), when comorbid with disruptive disorders (oppositional defiant disorder [ODD] or conduct disorder [CD]), with the internalizing disorders (anxiety and/or depression), or with both, should constitute separate clinical entities. Determination of the clinical significance of potential ADHD + internalizing disorder or ADHD + ODD/CD syndromes could yield better diagnostic decision-making, treatment planning, and treatment outcomes. METHOD: Drawing upon cross-sectional and longitudinal information from 579 children (aged 7-9.9 years) with ADHD participating in the NIMH Collaborative Multisite Multimodal Treatment Study of Children With Attention-Deficit/Hyperactivity Disorder (MTA), investigators applied validational criteria to compare ADHD subjects with and without comorbid internalizing disorders and ODD/CD. RESULTS: Substantial evidence of main effects of internalizing and externalizing comorbid disorders was found. Moderate evidence of interactions of parent-reported anxiety and ODD/CD status were noted on response to treatment, indicating that children with ADHD and anxiety disorders (but no ODD/CD) were likely to respond equally well to the MTA behavioral and medication treatments. Children with ADHD-only or ADHD with ODD/CD (but without anxiety disorders) responded best to MTA medication treatments (with or without behavioral treatments), while children with multiple comorbid disorders (anxiety and ODD/CD) responded optimally to combined (medication and behavioral) treatments. CONCLUSIONS: Findings indicate that three clinical profiles, ADHD co-occurring with internalizing disorders (principally parent-reported anxiety disorders) absent any concurrent disruptive disorder (ADHD + ANX), ADHD co-occurring with ODD/CD but no anxiety (ADHD + ODD/CD), and ADHD with both anxiety and ODD/CD (ADHD + ANX + ODD/CD) may be sufficiently distinct to warrant classification as ADHD subtypes different from "pure" ADHD with neither comorbidity. Future clinical, etiological, and genetics research should explore the merits of these three ADHD classification options.
Analysis of Variance↗
The epidemiology of attention-deficit/hyperactivity disorder (ADHD): a public health view.
Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder of childhood. However, basic information about how the prevalence of ADHD varies by race/ethnicity, sex, age, and socio-economic status remains poorly described. One reason is that difficulties in the diagnosis of ADHD have translated into difficulties developing an adequate case definition for epidemiologic studies. Diagnosis depends heavily on parent and teacher reports; no laboratory tests reliably predict ADHD. Prevalence estimates of ADHD are sensitive to who is asked what, and how information is combined. Consequently, recent systematic reviews report ADHD prevalence estimates as wide as 2%-18%. The diagnosis of ADHD is complicated by the frequent occurrence of comorbid conditions such as learning disability, conduct disorder, and anxiety disorder. Symptoms of these conditions may also mimic ADHD. Nevertheless, we suggest that developing an adequate epidemiologic case definition based on current diagnostic criteria is possible and is a prerequisite for further developing the epidemiology of ADHD. The etiology of ADHD is not known but recent studies suggest both a strong genetic link as well as environmental factors such as history of preterm delivery and perhaps, maternal smoking during pregnancy. Children and teenagers with ADHD use health and mental health services more often than their peers and engage in more health threatening behaviors such as smoking, and alcohol and substance abuse. Better methods are needed for monitoring the prevalence and understanding the public health implications of ADHD. Stimulant medication is the treatment of choice for treating ADHD but psychosocial interventions may also be warranted if comordid disorders are present. The treatment of ADHD is controversial because of the high prevalence of medication treatment. Epidemiologic studies could clarify whether the patterns of ADHD diagnosis and treatment in community settings is appropriate. Population-based epidemiologic studies may shed important new light on how we understand ADHD, its natural history, its treatment and its consequences.
Adolescent↗
Neuropsychological correlates of the YAQ-S and YAQ-I self- and informant-reported ADHD symptomatology, emotional and social problems and delinquent behaviour.
OBJECTIVES: The objective was to evaluate the relationship between self- and informant-rated symptoms of ADHD and performance on neuropsychological tests of attention and impulsivity (Letter Cancellation Test [LCT], Continuous Performance Test [CPT] and Matching Familiar Figures test [MFF]). DESIGN: Participants were clinical referrals for assessment of ADHD in adulthood and healthy controls. METHOD: ADHD adults were compared with individuals with mild psychiatric disorders (including attention problems), a healthy control group on neuropsychological measures of attention (CPT and LCT) and on impulsivity (MFF). Secondly, the scores obtained on these measures were correlated with the Young ADHD Questionnaire-S (YAQ-S) and Young ADHD Questionnaire-I (YAQ-I) self- and informant-reported scales of ADHD symptomatology, emotional problems, delinquency, and social functioning. RESULTS: The ADHD group were more impaired than the healthy controls on neuropsychological measures, but only the MFF differentiated them from the psychiatric controls. Tests of attentional control positively correlated with the selfreported functioning of the ADHD group but not among the psychiatric or normal controls. There was a positive correlation between tests of attention (but not impulsivity) and self-ratings of ADHD symptomatology for the ADHD group, suggesting that ADHD adults are better at recognizing attentional problems than impulse control. A positive correlation was found between the Delinquency scale and a test of impulsivity for the ADHD group only. CONCLUSIONS: The findings suggest that there are neuropsychological underpinnings of the ADHD syndrome but neuropsychological tests may discriminate poorly between ADHD and mild psychiatric disorders. ADHD adults may be more reliable informants of adult functioning than their parents, although they may underreport impulsive behaviour.
Adult↗
Perceptions of girls and ADHD: results from a national survey.
OBJECTIVE: The purpose of this survey is to explore perceived gender differences in attention-deficit/hyperactivity disorder (ADHD). METHODS: Online Harris Interactive interviews were conducted with 1797 adults (general public), 541 parents of children with ADHD, 550 teachers, and 346 children aged 12 to 17 years with ADHD. Responses were examined to determine perceptions of ADHD. RESULTS: Most of the general public (58%) and teachers (82%) think ADHD is more prevalent in boys. The general public and teachers think boys with ADHD are more likely than girls to have behavioral problems (public: 52% vs 26%; teachers: 36% vs 18%, respectively), while girls with ADHD are thought to have less noticeable problems than boys, such as being inattentive (public: 19% vs 11%; teachers: 29% vs 10%, respectively) or feeling depressed (public: 16% vs 1%; teachers: 12% vs 0.0%, respectively). Four out of 10 teachers report more difficulty in recognizing ADHD symptoms in girls. An overwhelming majority of teachers (85%) and more than half of the public (57%) and parents (54%) think girls with ADHD are more likely to remain undiagnosed. ADHD was reported to have a negative effect on self-esteem, more so in girls. Girls who were taking medication for their ADHD were nearly 3 times more likely to report antidepressant treatment prior to their ADHD diagnosis. Girls were more likely to feel it was "very difficult" to focus on schoolwork and get along with parents. CONCLUSIONS: Survey responses suggest that gender has important implications in the diagnosis and treatment of ADHD. Responses by ADHD patients demonstrate gender-specific differences in the personal experience of the condition. Future prospective clinical trials are warranted to clarify the unique needs and characteristics of girls with ADHD.
Adolescent↗
The methionine allele of the COMT polymorphism impairs prefrontal cognition in children and adolescents with ADHD.
ADHD is a highly heritable psychiatric disorder of childhood. A functional polymorphism (Val158Met) of the catechol-O-methyltransferase (COMT) gene has attracted interest as a candidate gene for ADHD. The high-activity valine variant of this polymorphism degrades prefrontal dopamine three to four times more quickly than the low-activity methionine variant and could therefore contribute to the proposed hypodopaminergic state in ADHD. Here we tested for association of this polymorphism with ADHD and examined its influence on prefrontal cognition in ADHD. We have previously reported no association of the Val158Met COMT gene polymorphism in 94 Irish ADHD families (Hawi et al. (2000) Am J Med Genet 96:282-284). Here we re-examined this finding with an extended sample of 179 ADHD cases using a family control design. We also examined the performance of children and adolescents with ADHD (n = 61) on a standardised test of sustained attention. Analysis confirmed the absence of an association between the Val158Met COMT gene polymorphism and the clinical phenotype of ADHD. COMT genotype, however, affected prefrontal cognition in ADHD: ADHD children who were homozygous for the valine variant had significantly better sustained attention than those ADHD children possessing at least one copy of the methionine variant. Children possessing the methionine variant performed significantly below age-related norms on tests of sustained attention. Contrary to expectations, the methionine variant of the Val158Met COMT gene polymorphism impaired prefrontally-mediated cognition in ADHD. This effect may be understood by positing a hyper-functioning of prefrontal dopaminergic systems. Against this background, the slower clearance of dopamine associated with the methionine variant of the COMT gene polymorphism may be disadvantageous to cognition in ADHD.
Adolescent↗
ADHD subtypes: do they differ in their executive functioning profile?
The present study was designed to investigate the hypothesis that children with Attention Deficit Hyperactivity Disorder combined subtype (ADHD-C) have a generalized executive functioning (EF) [Barkley, R. A. (1997). Behavioural inhibition, sustained attention, and executive functions: Constructing a unifying theory of AD/HD. Psychological Bulletin, 121, 65-94; Barkley, R. A. (1997). ADHD and the nature of self-control. New York: The Guilford Press]. We tested whether ADHD-C and ADHD inattentive subtype (ADHD-I) can be differentiated from each other on EF measures. We compared 16 normally developing boys with 16 boys with ADHD-C and 16 with ADHD-I on five EF domains. The boys were all matched on age, IQ, and the presence of oppositional defiant disorder (ODD)/conduct disorder (CD). Despite carefully diagnosed groups and methodological controls, the results do not support the EF-hypothesis of ADHD-C. Children with ADHD-C differed from normal controls (NC) on tasks related to inhibition; they did not exhibit EF deficits on all EF tasks. Children with ADHD-C also exhibited deficits on non-EF tasks. Furthermore, the ADHD-C and ADHD-I subtypes did not differ from one another. Neuropsychological findings on the domains under study did not yield evidence for the distinctiveness of ADHD-C and ADHD-I subtypes.
Adolescent↗
Neuropsychological functioning in people with ADHD across the lifespan.
ADHD is defined by behavioral characteristics similar to neuropsychological disorders of executive dysfunction. This paper is a literature review of the neurocognitive characteristics of ADHD from early childhood through adulthood. The author addresses the development of the concept of attention and executive function (EF) deficits in ADHD, clinical neuropsychological studies of pre-teenage children, teenagers and adults with ADHD, gender and the role of psychiatric co-morbidity including the relationship of learning disabilities to ADHD, heterogeneity of neuropsychological dysfunctions, experimental neuropsychological studies, the relationship of brain structure to function, psychopharmacology of ADHD, and clinical neuropsychological assessment. The group data clearly supports the hypothesis that executive dysfunctions are correlates of ADHD regardless of gender and age, and these EF deficits are exacerbated by co-morbidity with learning disabilities such as dyslexia. However, there is limited data on children under the age of 5, teenagers from age 13-18, and adults with ADHD over the age of 40. Studies of individual classification of people with ADHD compared to healthy, non-psychiatric controls do not support the use of neuropsychological tests for the clinical diagnosis of ADHD, and indicate that not all persons with ADHD have EF deficits. Some persons with ADHD may have deficits in brain reward systems that are relatively independent of EF impairments. Future research should clarify the multiple sources of ADHD impairments, continue to refine neuropsychological tools optimized for assessment, and incorporate longitudinal, developmental designs to understand ADHD across the lifespan.
Attention Deficit Disorder with Hyperactivity↗