Attention deficit/hyperactivity disorder and ethnicity

Using digital measurement-based care to address symptoms of inattention, hyperactivity, and opposition in youth: A retrospective analysis of Bend Health (Preprint)

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and associated behavioral disorders are highly prevalent in children and adolescents, yet many of them do not receive the care they need. Digital mental health interventions (DMHIs) may address this need by providing accessible and high-quality care. Given the necessity for high levels of caregiver and primary care practitioner involvement in addressing ADHD symptoms and behavioral problems, collaborative care interventions that adopt a whole-family approach may be particularly well suited to reduce symptoms of inattention, hyperactivity, and opposition in children and adolescents.

OBJECTIVE

The purpose of this study is to use member (ie, child and adolescent) data from Bend Health, Inc, a collaborative care DMHI that uses a whole-family approach to address child and adolescent mental health concerns, to (1) determine the effects of a collaborative care DMHI on inattention, hyperactivity, and oppositional symptoms in children and adolescents and (2) assess whether the effects of a collaborative care DMHI vary across ADHD subtypes and demographic factors.

METHODS

Caregivers of children and adolescents with elevated symptoms of inattention, hyperactivity, or opposition assessed their children's symptom severity approximately every 30 days while participating in Bend Health, Inc. Data from 107 children and adolescents aged 6-17 years who exhibited clinically elevated symptoms at baseline were used to assess symptom severity across monthly assessments (inattention symptom group: n=91, 85.0%; hyperactivity symptom group: n=48, 44.9%; oppositional symptom group: n=70, 65.4%). The majority of the sample exhibited elevated symptoms of at least 2 symptom types at baseline (n=67, 62.6%).

RESULTS

Members received care for up to 5.52 months and attended between 0 and 10 coaching, therapy, or psychiatry sessions through Bend Health, Inc. For those with at least 2 assessments, 71.0% (n=22) showed improvements in inattention symptoms, 60.0% (n=9) showed improvements in hyperactivity symptoms, and 60.0% (n=12) showed improvements in oppositional symptoms. When considering group-level change over time, symptom severity decreased over the course of treatment with Bend Health, Inc, for inattention (average decrease=3.51 points, P=.001) and hyperactivity (average decrease=3.07 points, P=.049) but not for oppositional symptoms (average decrease=0.70 points, P=.26). There was a main effect of the duration of care on symptom severity (P<.001) such that each additional month of care was associated with lower symptom scores.

CONCLUSIONS

This study offers promising early evidence that collaborative care DHMIs may facilitate improvements in ADHD symptoms among children and adolescents, addressing the growing need for accessible and high-quality care for behavioral health problems in the United States. However, additional follow-up studies bolstered by larger samples and control groups are necessary to further establish the robustness of these findings.

The continuum of attention dysfunction: Evidence from dynamic functional network connectivity analysis in neurotypical adolescents

The question of whether attention-related disorders such as attention-deficit/hyperactivity disorder (ADHD) are best understood as clinical categories or as extreme ends of a spectrum is an ongoing debate. Assessing individuals with varying degrees of attention problems and utilizing novel methodologies to assess relationships between attention and brain activity may provide key information to support the spectrum hypothesis. We scanned 91 neurotypical adolescents during rest using functional magnetic resonance imaging. We conducted static and dynamic functional network connectivity (FNC) analysis and correlated findings to behavioral metrics of ADHD, attention problems, and impulsivity. We found that dynamic FNC analysis detects significant differences in large-scale neural connectivity as a function of individual differences in attention and impulsivity that are obscured in static analysis. We show ADHD manifestations and attention problems are associated with diminished Salience Network-centered FNC and that ADHD manifestations and impulsivity are associated with prolonged periods of dynamically hyperconnected states. Importantly, our meta-state analysis results reveal a relationship between ADHD manifestations and exhibiting variable and volatile dynamic behavior such as changing meta-states more often and traveling over a greater dynamic range. These findings in non-clinical adolescents provide support for the continuum model of attention disorders.

Screen Time and ADHD Behaviors in Chinese Children: Findings From Longitudinal and Cross-Sectional Data

OBJECTIVE

Research suggests that screen exposure presents a risk for ADHD behaviors in young children. However, the operationalization of screen exposure remains murky and longitudinal data is scarce. In this paper, we examined the relations between better operationalized daily screen time and behaviors of inattention and behaviors of hyperactivity/impulsivity in three cohorts of community samples of young Chinese children.

METHOD

Study 1 was longitudinal and included 111 children who were 3.6 years old (Range = 2.4-4.9; SD = 0.4) at Baseline and 4.8 years old (Range = 3.9-6.0; SD = 0.4) at Follow-Up. Study 2 was cross-sectional and included 172 children aged 4.9 years (Range = 3.0-7.1; SD = 1.0). Study 3 was also cross-sectional and included 313 children who were 6.9 years old (Range = 5.7-8.3; SD = 0.4). In each study, the parents reported how much time that their children spent daily on iPad/tablet, smart phone, and online games and watching TV in the previous week, and their children's behaviors of inattention (I/A) and hyperactivity/impulsivity (H/I).

RESULTS

Regression analysis revealed that in Study 1, controlling for child demographics, mother's education, family SES, and corresponding I/A or H/I scores at Baseline, screen time at Baseline predicted I/A scores (β = .27, p < .01) and H/I scores (β = .32, p < .001) at Follow-Up. Similarly, controlling for covariates, screen time predicted I/A scores (β = .25, p < .01) and H/I scores (β = .25, p < .01) in Study 2; I/A scores (β = 0.16, p < .01) and H/I scores (β = .15, p < .05) in Study 3.

CONCLUSION

Screen exposure was a risk for inattention and hyperactivity/impulsivity behaviors in urban Chinese children.

Maternal Sociodemographic Factors Are Associated with Methylphenidate Initiation in Children in the Netherlands: A Population-Based Study

Multiple factors may contribute to the decision to initiate methylphenidate treatment in children such as maternal sociodemographic factors of which relatively little is known. The objective was to investigate the association between these factors and methylphenidate initiation. The study population included 4243 children from the Generation R Study in the Netherlands. Maternal sociodemographic characteristics were tested as determinants of methylphenidate initiation through a time-dependent Cox regression analysis. Subsequently, we stratified by mother-reported ADHD symptoms (present in 4.2% of the study population). When ADHD symptoms were absent, we found that girls (adjusted HR 0.25, 95%CI 0.16-0.39) and children born to a mother with a non-western ethnicity (compared to Dutch-Caucasian) (adjusted HR 0.42, 95%CI 015-0.68) were less likely to receive methylphenidate. They were more likely to receive methylphenidate when their mother completed a low (adjusted HR 2.29, 95%CI 1.10-4.77) or secondary (adjusted HR 1.71, 95%CI 1.16-2.54) education. In conclusion, boys and children born to a mother of Dutch-Caucasian ethnicity were more likely to receive methylphenidate, irrespective of the presence of ADHD symptoms.

Predicting ADHD symptoms and diagnosis at age 14 from objective activity levels at age 7 in a large UK cohort

Hyperactivity is one of the three core symptoms in children with attention deficit hyperactivity disorder (ADHD). Diagnosing ADHD typically involves self-report, third party report and observations. Objective activity data can make a valuable contribution to the diagnostic process. Small actigraphy studies in clinical samples have shown that children with ADHD move more than children without ADHD. However, differences in physical activity between children with and without ADHD have not been assessed in large community samples or longitudinally. This study used data from the Millennium Cohort Study to test whether symptoms of ADHD (parent-rating Strengths and Difficulties Questionnaire) and ADHD diagnosis at age 14 (reported by parents) could be predicted from objective activity data (measured with actigraphs) at age 7 in N = 6675 children (final N = 5251). Regressions showed that less sedentary behavior at age 7 predicted more ADHD symptoms at age 14 (β =  - 0.002, CI  - 0.004 to  - 0.001). The result remained significant when controlled for ADHD symptoms at age 7, sex, BMI, month of birth, SES and ethnicity (β  =  - 0.001, CI  - 0.003 to  - 0.0003). ADHD diagnosis at age 14 was also significantly predicted by less sedentary behavior at age 7 (β  =  - 0.008). Our findings show that symptoms of ADHD can be predicted by objective activity data 5 years in advance and suggest that actigraphy could be a useful instrument aiding an ADHD diagnosis. Interestingly, the results indicate that the key difference between children with and without ADHD lies in reduced sedentary activity, i.e., times of rest.

Attention-deficit hyperactivity disorder in school-age children in Gaborone, Botswana: Comorbidity and risk factors

Background

Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in children. Its occurrence and pattern of presentation are unknown in Botswana.

Aim

To determine the prevalence of attention-deficit hyperactivity disorder (ADHD), associated comorbid conditions and risk factors amongst school-age children in Botswana.

Setting

Primary schools in Gaborone, Botswana.

Methods

This study used a cross-sectional design. A two-stage random sampling technique was utilised to select learners from 25 out of the 29 public schools in the city. The Vanderbilt ADHD Diagnostic Rating Scale (VADRS), teacher and parent versions, was administered.

Results

Of the 1737 children, 50.9% (n = 884) were male, and their mean age was 9.53 years (s.d. = 1.97). The prevalence of ADHD was 12.3% (n = 213). The most prevalent presentation was the predominantly inattentive, 7.2% (n = 125). A family history of mental illness (odds ratio [OR] = 6.59, 95% CI: 1.36–32.0) and perinatal complications (OR = 2.16, 95% CI: 1.08–4.29) emerged as the independent predictors of ADHD.

Conclusions

The prevalence of ADHD in Botswana is slightly higher than that reported in the literature, but the pattern of presentations and comorbidities is similar. A positive family history of mental illness and perinatal complications independently predicted ADHD. Mental health screening amongst families of the affected individuals and improved perinatal care should be considered as health care priorities in Botswana.

Reliability, Validity, Factor Structure, and Measurement Invariance of the Japanese Conners’ Adult ADHD Rating Scales (CAARS)

To examine reliability, validity, factor structure, and measurement invariance (i.e., configural, metric, and scalar invariance) of the Japanese Conners’ Adult attention deficit hyperactivity disorder (ADHD) Rating Scales (CAARS), Japanese nonclinical adults ( N = 786) completed the CAARS Self-Report (CAARS-S). Each participant was also rated by one observer using the CAARS Observer Form (CAARS-O). For the test of measurement invariance, excerpts from the original (North American) CAARS norming data ( N = 500) were used. Dimensional structure was examined by exploratory and confirmatory factor analyses. Test–retest reliability, internal consistency, and concurrent validity were satisfactory. Based on the DSM-IV model and Japanese four-factor model, configural and metric invariance were established for the CAARS-S/O across Japanese and North American populations. Scalar invariance was established for the CAARS-O based on the Japanese model. The use of the Japanese CAARS for diagnostic purposes in Japan was supported; however, it should be used with caution for cross-cultural comparison research.

[Formula: see text]Cognitive and behavioral rating measures of executive function as predictors of academic outcomes in children

Interrelations of two measurement methods (cognitive versus behavioral ratings) for executive function (EF) were examined and related to reading comprehension and math calculations in fourth and fifth grade students (n = 93) in the context of a diverse urban student population. Relations among measures within four EF processes (working memory, planning, inhibition and shifting) were modest; relations to academics were stronger. EF measures contributed to both academic outcomes even in the context of relevant covariates (age, language and educational program). Working memory was particularly important for reading comprehension across measurement type. Cognitive measures from all EF processes, particularly inhibition and planning, and behavioral ratings of working memory were important for math.

Comorbidity and continuity of attention deficit hyperactivity disorder (ADHD) from childhood to adolescence in Turkey

The aim of this study was to examine clinical outcomes, psychiatric comorbidity and neuropsychological characteristics in Turkish adolescents with an attention deficit hyperactivity disorder (ADHD) diagnosis in childhood. A total of 45 children with ADHD diagnosis and 28 children with a psychiatric diagnosis other than ADHD in a 1-year cohort of 7-10-year-olds were reevaluated 6 years later using Schedule for Affective Disorders and Schizophrenia for School-Age Children Present and Lifetime version and Wechsler Intelligence Scale for Children-Revised and Stroop Test TBAG version. This study shows that the clinical outcomes and the comorbidity patterns for ADHD from childhood to adolescence in Turkey are similar to reported rates in the Western countries. In the ADHD group, 75.6 % still has impairing ADHD symptoms and 46.6 % has comorbid psychiatric disorders. The main difference is anxiety disorders being the most common comorbid disorders (37.8 %) in Turkish ADHD youth. These findings stress the high comorbidity associated with ADHD and support the importance of assessment and treatment for ADHD and comorbidities during adolescence.

Rat models of ADHD

Showing that an animal is hyperactive is not sufficient for it to be accepted as a model of ADHD. Based on behavioral, genetic, and neurobiological data, the spontaneously hypertensive rat (SHR) obtained from Charles River, Germany, (SHR/NCrl) is at present the best-validated animal model of ADHD. One Wistar Kyoto substrain (WKY/NHsd), obtained from Harlan, UK, is its most appropriate control. Another WKY substrain (WKY/NCrl) obtained from Charles River, Germany, is inattentive, has distinctly different genetics and neurobiology, and provides a promising model for the predominantly inattentive subtype of ADHD (ADHD-I) if one wants to investigate categorical ADHD subtypes. In this case, also, the WKY/NHsd substrain should be used as control. Although other rat strains may behave like WKY/NHsd rats, neurobiological results indicate significant differences when compared to the WKY/NHsd substrain, making them less suitable as controls for the SHR/NCrl. Thus, there are no obvious behavioral differences among the various SHRs, but there are behavioral and neurobiological differences among the WKY strains. The use of WKY/NCrl, outbred Wistar, Sprague Dawley, or other rat strains as controls for SHR/NCrl may produce spurious neurobiological effects and erroneous conclusions. Finally, model data yield support to independent hyperactivity and inattention dimensions in ADHD behavior.

Adults with ADHD: who are we missing?

Attention deficit hyperactivity disorder (ADHD) has long been identified as a common disorder of childhood. There is increasing recognition that adults also are affected by this disorder. Many adults, however, are often undiagnosed or misdiagnosed until their child is diagnosed with the disorder. Improved recognition and treatment for parental ADHD needs to occur given the genetic and environmental etiologies of the disorder. This paper examines three areas where there is a dearth of data in extant literature: parental ADHD culture and ethnicity; parenting and undiagnosed ADHD; and professional care and ADHD, and focuses on parents from ethnic minority cultures.

Racial differences in the effects of postnatal environmental tobacco smoke on neurodevelopment

OBJECTIVES

We used the 2001-2004 National Health and Nutrition Examination Survey to examine the association between postnatal environmental tobacco smoke exposure, measured as serum cotinine levels, and attention-deficit/hyperactivity disorder (ADHD) among children 4 to 15 years of age. We further investigated the interactions of race and serum cotinine levels with ADHD.

METHODS

Logistic regression models were used to evaluate associations.

RESULTS

This study found that the prevalence of ADHD increased as blood cotinine levels increased. The effects of blood cotinine levels on ADHD differed according to race. Compared with children of the same racial group with the lowest blood cotinine levels, the odds ratios were 2.72 (95% confidence interval: 1.25-5.93) for Mexican American children and 5.32 (95% confidence interval: 1.55-18.3) for children in other racial groups with the highest blood cotinine levels, with controlling for the effect of maternal smoking during pregnancy. However, no significant associations between blood cotinine levels and ADHD were observed among non-Hispanic white or non-Hispanic black children.

CONCLUSIONS

The findings of this study underscore the possibility of racial disparities in the effects of environmental tobacco smoke on behavioral problems in children. These findings warrant further investigation.

Meditation therapies for attention-deficit/hyperactivity disorder (ADHD)

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common developmental disorders experienced in childhood and can persist into adulthood. The disorder has early onset and is characterized by a combination of overactive, poorly modulated behavior with marked inattention. In the long term it can impair academic performance, vocational success and social-emotional development. Meditation is increasingly used for psychological conditions and could be used as a tool for attentional training in the ADHD population.

OBJECTIVES

To assess the effectiveness of meditation therapies as a treatment for ADHD.

SEARCH STRATEGY

Our extensive search included: CENTRAL, MEDLINE, EMBASE, CINAHL, ERIC, PsycINFO, C2-SPECTR, dissertation abstracts, LILACS, Virtual Health Library (VHL) in BIREME, Complementary and Alternative Medicine specific databases, HSTAT, Informit, JST, Thai Psychiatric databases and ISI Proceedings, plus grey literature and trial registries from inception to January 2010.

SELECTION CRITERIA

Randomized controlled trials that investigated the efficacy of meditation therapy in children or adults diagnosed with ADHD.

DATA COLLECTION AND ANALYSIS

Two authors extracted data independently using a pre-designed data extraction form. We contacted study authors for additional information required. We analyzed data using mean difference (MD) to calculate the treatment effect. The results are presented in tables, figures and narrative form.

MAIN RESULTS

Four studies, including 83 participants, are included in this review. Two studies used mantra meditation while the other two used yoga compared with drugs, relaxation training, non-specific exercises and standard treatment control. Design limitations caused high risk of bias across the studies. Only one out of four studies provided data appropriate for analysis. For this study there was no statistically significant difference between the meditation therapy group and the drug therapy group on the teacher rating ADHD scale (MD -2.72, 95% CI -8.49 to 3.05, 15 patients). Likewise, there was no statistically significant difference between the meditation therapy group and the standard therapy group on the teacher rating ADHD scale (MD -0.52, 95% CI -5.88 to 4.84, 17 patients). There was also no statistically significant difference between the meditation therapy group and the standard therapy group in the distraction test (MD -8.34, 95% CI -107.05 to 90.37, 17 patients).

AUTHORS' CONCLUSIONS

As a result of the limited number of included studies, the small sample sizes and the high risk of bias, we are unable to draw any conclusions regarding the effectiveness of meditation therapy for ADHD. The adverse effects of meditation have not been reported. More trials are needed.

Origins of altered reinforcement effects in ADHD

Attention-deficit/hyperactivity disorder (ADHD), characterized by hyperactivity, impulsiveness and deficient sustained attention, is one of the most common and persistent behavioral disorders of childhood. ADHD is associated with catecholamine dysfunction. The catecholamines are important for response selection and memory formation, and dopamine in particular is important for reinforcement of successful behavior. The convergence of dopaminergic mesolimbic and glutamatergic corticostriatal synapses upon individual neostriatal neurons provides a favorable substrate for a three-factor synaptic modification rule underlying acquisition of associations between stimuli in a particular context, responses, and reinforcers. The change in associative strength as a function of delay between key stimuli or responses, and reinforcement, is known as the delay of reinforcement gradient. The gradient is altered by vicissitudes of attention, intrusions of irrelevant events, lapses of memory, and fluctuations in dopamine function. Theoretical and experimental analyses of these moderating factors will help to determine just how reinforcement processes are altered in ADHD. Such analyses can only help to improve treatment strategies for ADHD.

Prevalence rates of attention deficit/hyperactivity disorder in a school sample of Venezuelan children

A total of 1,535 4-12 year-old children were screened with the Conners' rating scales, followed by diagnostic confirmation by the diagnostic interview schedule for children-IV-parent version. The prevalence of ADHD was estimated to be 10.03%, and only 3.9% of children had received medication for the treatment of ADHD symptoms. Prevalence rates and demographic profile of Venezuelan children with ADHD are very similar to those found in samples from other countries. Authorities need to develop public health policies to correctly identify and treat affected subjects. Furthermore, clinicians must actively search for children with ADHD in order to provide the best-available treatment.

ADHD symptoms and associated psychopathology in a community sample of adolescents from the European north of Russia

OBJECTIVE

To assess the prevalence of ADHD symptoms and their relationship to psychopathology in adolescents from the European North of Russia.

METHOD

The prevalence of ADHD symptoms is assessed by teacher reports in 536 adolescents. Internalizing and externalizing problems are assessed by teacher ratings and student self-reports.

RESULTS

Prevalence of individual ADHD symptoms ranges between 3.3% and 35%. Only 8.9% of boys and 3.6% of girls have positive ratings on six items in either inattention or hyperactivity subtype. These adolescents fare significantly worse regarding externalizing but not internalizing problems. Compared to girls with ADHD, boys with ADHD report higher levels of violent and nonviolent delinquency and are described by teachers as having more conduct problems. Possible ADHD status is associated with depressive symptoms in boys but not in girls.

CONCLUSION

The estimates of ADHD prevalence rates obtained in this study are similar to those of other countries, suggesting the need for identification and treatment of the disorder. Evaluation of associated disruptive behavior disorders and depression, particularly in boys, is warranted.

Psychiatric comorbidity and functional impairment in a clinically referred sample of adults with attention-deficit/hyperactivity disorder (ADHD)

OBJECTIVE

This exploratory study aims to compare lifetime psychiatric axis-I-comorbidity and psychosocial functioning in a clinically referred sample of adult patients with attention-deficit/hyperactivity disorder (ADHD) with a population-based healthy control group and to examine whether patients with ADHD and lifetime comorbid diagnoses differ from patients with pure ADHD in their functional impairment.

METHOD

Seventy adult patients with ADHD according to DSM-IV criteria and a gender- as well as age-matched population based control group underwent diagnostic evaluations with clinical interviews for ADHD, DSM-IV disorders and demographic information.

RESULTS

The prevalence of psychiatric lifetime comorbidity was 77.1% in patients with ADHD and thus exceeded the rate in the control group, which was 45.7%. Significantly more patients suffered from depressive episodes, substance related disorders and eating disorders. Compared to the control group adults with ADHD were significantly impaired in a variety of psychosocial functions (education, occupational training). Patients with ADHD and lifetime diagnosis of comorbid psychiatric disorders differed from patients with pure ADHD in their psychosocial functioning only in the percentage of unemployed individuals, which was higher in patients with psychiatric comorbidity.

CONCLUSION

Adults with ADHD suffer significantly more often from other psychiatric disorders than individuals of the population-based control group and are impaired in several areas of psychosocial functioning. Poor psychosocial outcome is primarily related to ADHD and not to additional psychiatric disorders. Due to the limited number of assessed patients these results need to be confirmed by studies with larger sample size.

A cross-cultural comparison between samples of Brazilian and German children with ADHD/HD using the Child Behavior Checklist

INTRODUCTION

This study aims to assess cross-cultural similarities and differences in broadband psychopathology in two naturalistic clinical samples of children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) combined type according to DSM-IV criteria or with Hyperkinetic Disorder (HD) according to ICD-10 criteria.

METHODS

We compared two clinical samples of children with ADHD combined type (Brazil, N=248) and HD (Germany; N=154) to controls (Brazil N=71; Germany N=135) using the Child Behavior Checklist (CBCL). ROC-curves (Receiver Operating Characteristic) were determined to evaluate the discriminating validity of the CBCL Attention Problem scale. A two-factorial ANOVA was computed across all 8 scales of the CBCL.

RESULTS

Although Brazilian parents reported significantly higher scores on all CBCL scales than German parents (P<0.05), a similar CBCL profile was detected in both cultures.

CONCLUSION

Despite the use of different diagnostic systems (DSM-IV vs. ICD-10) and the presence of other clinical differences, the similar broadband psychopathological profile of the CBCL in the two samples provides evidence that dimensional symptoms associated with the categorical diagnosis of ADHD combined type might be comparable in two clinical settings with diverse cultural background.

Psychosocial treatments for children with attention deficit/hyperactivity disorder

This article reviews studies examining the efficacy of behavioral interventions for the treatment of attention-deficit/hyperactivity disorder (ADHD). A specific emphasis is placed on evidence-based interventions that include parent training, classroom, academic, and peer interventions. Results indicate that school-aged children respond to behavioral interventions when they are appropriately implemented both at home and in the classroom setting. Combined treatments (behavioral management and stimulant medication) represent the gold standard in ADHD treatment and are often recommended as the first-line treatment option due to the many problems faced by children with ADHD. Diversity issues, although an important consideration in the treatment of ADHD, continue to remain an understudied area. Recommendations for future research are made pertaining to treatment sequencing with regard to behavior management as well as for subgroups of ADHD children who may respond best to specific treatments.

Determination of atomoxetine in human plasma by a high performance liquid chromatographic method with ultraviolet detection using liquid–liquid extraction

A HPLC method with UV detection (210 nm) was developed and validated for the quantification of atomoxetine, a new medication for the treatment of attention deficit/hyperactivity disorder, in human plasma. Following a two-step liquid-liquid extraction with diethyl ether, the analyte and internal standard (maprotiline) were separated using an isocratic mobile phase of acetonitrile/phosphate buffer (39/61, v/v, pH 6.6) on a reverse phase Inertsil C(18) column. Linearity was verified over the range of 3.12-200 ng/mL atomoxetine in plasma. The lowest limit of detection is 2.5 ng/mL (S/N=10). This HPLC method was validated with within- and between-batch precisions of 4.9-14.4% and 4.7-13.1%, respectively. The within- and between-batch biases were -1.9 to 1.4% and 0.1-13.8%, respectively. Commonly used psychotropic drugs and frequently coadministered drugs did not interfere with the drug and internal standard. This method is simple, economical and specific, and has been used successfully in a pharmacokinetic study of atomoxetine.

Attention deficit hyperactivity disorder among Nigerian primary school children: prevalence and co-morbid conditions

OBJECTIVE

This study aimed to determine the prevalence of ADHD and co-morbid conditions in a sample of primary school children aged 7-12 years in Nigeria.

METHOD

A two-staged procedure in which primary school pupils aged 6-12 years (n = 1112) were assessed for DSM-IV criteria of attention deficit hyperactivity disorder (ADHD) by their teachers in the first stage and their parents in the second stage. A flexible criterion was used for estimating the prevalence.

RESULTS

The prevalence of ADHD was 8.7%. The prevalence of the subtypes were: predominantly Inattentive 4.9%, predominantly hyperactive/impulsive 1.2% and combined 2.6%. The male to female ratio was 2:1 for all the subtypes of ADHD except hyperactive/impulsive which was 3.2:1. The co-morbid conditions include oppositional defiant disorder (ODD - 25.8%), conduct disorder (CD - 9.3%) and anxiety/depression (20.6%). While ODD and CD were associated with the hyperactive/impulsive subtype, anxiety/depression was associated with inattentive subtype.

CONCLUSION

Our findings support the notion that ADHD occurs across cultures. Given the prevalent rate, efforts should be made to map out strategies for early identification and referral of these children for proper evaluation and treatment. This study can serve as a platform for future analytical studies about this challenging research issue in sub-Saharan Africa.

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 86^th 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.