The general aim of the thesis was to contribute to the knowledge about co-occurring symptoms of ADHD and depression in adolescence, focusing on sex differences, as well as aetiology, help-seeking and assessment. Studies I–III used epidemiological samples of self-reports from all students in Västmanland aged 15–16 and 17–18 years. Study I investigated the prevalence of co-occurring symptoms of ADHD and depression, as well as associations between co-occurring symptoms of ADHD and depression and one environmental stress factor; experience of sexual abuse. Study II examined associations between one biological factor—a polymorphism in TFAP-2β—and co-occurring symptoms of ADHD with andco-occurringsymptoms of depression. Study III investigated the association between the parent–adolescent relationship and seeking help from specialized mental health services in relation to symptoms of ADHD and/or depression. Study IV was a clinical study among adolescent psychiatric patients that compared self-reported ADHD symptoms via the Adult ADHD Self-Report Scale–Adolescent version (ASRS-A) and the Adult ADHD Self-Report Scale–Adolescent–Screening version (ASRS-A-S) with an ADHD diagnosis determined by the gold-standard method; the Kiddie Schedule of Affective Disorders and Schizophrenia diagnostic interview. Studies I–III showed that the phenotype of co-occurring symptoms of ADHD and depression is frequent, with a distinct preponderance among girls. Approximately 50% of both boys and girls with co-occurring symptoms of ADHD and depression had also experienced sexual abuse, indicating that this is a group with multiple risk factors for long-term impaired mental health. Results also support biological sex differences because girls with symptoms of ADHD and a common polymorphism of TFAP-2β (absence of a 9 repeat) reported more symptoms of depression, but boys did not. Further, only 5% of the adolescents with symptoms of ADHD and/or depression sought help from specialized mental health services. The co-occurrence of symptoms of ADHD and depression was a stronger predictor of help-seeking than all other psychosocial factors investigated, including secure attachment cognitions styles to parents. Among help-seeking girls, co-occurring symptoms of ADHD and depression were more common than symptoms of ADHD without co-occurring symptoms of depression. The ASRS-A/ASRS-A-S showed promising psychometric properties for further validation in adolescentsresults as a screening tool for use in adolescents.

The general aim of this study was to investigate the prescribing patterns of products that contain methylphenidate or atomoxetine in a section of the private health care sector of South Africa. A quantitative, retrospective drug uitilisation review was performed according to data obtained from the database of a South African medicine claims pharmacy benefit management company's for three consecutive study years (Le. 2005 to 2007). The results indicated that a total of 7,990 patients had been prescribed products that contained methylphenidate or atomoxetine in 2005. The total for 2006 was 8,575 and it decreased to a total of 7,828 in 2007. Of all the patients who received the mentioned products, the percentage for females increased from 27.75% (N = 7,990) in 2005 to 29.06% (N =7,828) in 2007. With regard to the same products the percentage for males decreased from 72.03% (N = 7,990) in 2005 to 70.89% (N = 7,828) in 2007. The ratio for the gender-related prescribing patterns of medicine items that contained methylphenidate or atomoxetine in this section of the private health care sector of South Africa was ± 2.55:1 for males to females in comparison with the international male:female ratio of 3:1. According to the medicine claims on the database for 2005 the total number of prescriptions that indicated products containing methylphenidate or atomoxetine was calculated as 8,522, 798 (i.e. N = 8, 522,798) or as a percentage of 0.32% prescriptions. The percentage showed an increase to 0.41 % in 2007 (N = 8,015,538). Of all the medicine items containing methylphenidate or atomoxetine those products that contained atomoxetine represented 4.69% and those that contained methylphenidate represented 95.31%. In 2005 the average cost per prescription that indicated items containing methylphenidate or atomoxetine amounted to R318.29 ± R162.09. In 2007 the amount increased to R358.91 ± R208.10. The percentage of children younger than five years of age, and who had been prescribed products containing methylphenidate or atomoxetine, increased from 0.91 % in 2005 (N = 7,990) to 1.11 % in 2007 (N =7,828). The percentage for children aged 5 to 12 years decreased from 53.62% in 2005 to 49.23% in 2007. For adolescents the percentage increased from 26.32% in 2005 to 27.35% in 2007. The same pattern repeated itself in the case of adults (age 18+ years). Among the top trade name products prescribed were Ritalin LA 20mg®, Ritalin 20mg®, Concerta 36mg®, Ritalin LA 30mg® and Concerta 18mg®. Possible drug-drug interactions were found between products containing methylphenidate or atomoxetine and products containing imipramine, amitriptyline and carbamazepine. Findings indicated that the number of products containing methylphenidate or atomoxetine increased from 2005 to 2007, while also revealing that those products containing methylphenidate remained in the majority. The average costs of products containing methylphenidate or atomoxetine increased from 2005 to 2007. / Thesis (M.Pharm. (Pharmacy Practice))--North-West University, Potchefstroom Campus, 2010.

This study examined the impact of working memory deficits (WMD) on the academic achievement of adolescents with ADHD. Adolescents (n=79) aged 13 to 17 years with a clinical diagnosis of ADHD were subtyped into those with and without WMD based on impairment in at least two measures, and then compared on their academic achievement and clinical profile. Results indicated that adolescents with ADHD plus WMD (23%) manifest significantly lower academic achievement than those with adequate WM. By contrast, there were no group differences in psychiatric comorbidity, severity of ADHD symptoms and psychological adjustment. We also found a unique contribution of WM to academic achievement over and above that of other clinical features. These findings suggest that WMD compromise the educational attainment of a subgroup of individuals with ADHD. Individuals with ADHD should be screened for WMD to prevent academic failure and WM should be considered as a treatment target.

Attention-Deficit / Hyperactivity Disorder (ADHD) is characterized by higher than normal levels of inattention, hyperactivity and impulsivity. Behavioural inhibition is proposed to be a primary deficit in children with ADHD, and is included as a component of a number of models accounting for the core behavioural symptoms of ADHD. Children with ADHD often show deficits in their performance on behavioural inhibition tasks relative to typically developing children of the same age, although inconsistent findings have been observed. Stimulant medication is associated with reduction in the core symptoms of ADHD in the majority of children. The primary goal of this thesis was to examine the effects of stimulant medication on behavioural inhibition in children with ADHD. Furthermore, this thesis sought to determine whether children with ADHD who have, and have not taken stimulant medication differ from normally developing children in terms of behavioural inhibition. In order to achieve these aims, it was necessary to firstly determine which tasks provide the best measures of behavioural inhibition. While many tasks have been used to measure inhibitory control amongst children with ADHD, it was unclear from previous research which tasks measure the same constructs. Study 1 investigated relationships in task performance among seven measures of inhibitory control, including the Stop-Signal task, Go / No-go task, Sustained Attention to Response Task (SART; analogous the not-X Continuous Performance Task), Eriksen Flanker task, Stroop, Opposite Worlds task and Task-Switching task. Significant developmental changes in a variety of cognitive abilities occur across childhood and adolescence. To limit the possibility that developmental changes in task performance would be observed, the age range for children included in the study was restricted to seven to 10 years. Nevertheless, to interpret correlations among inhibition measures from the tasks, it was necessary to determine whether children showed comparable developmental trends in their performance across tasks. Study 1A investigated developmental changes in the performances of the seven tasks purported to measure inhibitory control in normally developing children aged seven to 10 years. The results of this study suggested that the tasks chosen were appropriate for use among this age group, and that there is little change in behavioural inhibition across the seven to 10 years age range. In Study 1B, inhibition measures from each of the tasks were included in an exploratory factor analysis to determine those tasks measuring the same constructs. The results of Study 1B suggested that the Stop-Signal, Go / No-go and SART tasks provided the best measures of the behavioural inhibition construct. Performance on the Eriksen Flanker task was also related to the performance on these tasks, but in a direction contrary to that predicted. The Stroop and Opposite Worlds tasks measured the same construct, which appeared to be interference control. Performance on the Task-Switching task was not related to the performance on any other task, suggesting that this task did not measure behavioural inhibition or interference control. Study 2 investigated the performance of children with ADHD on the three tasks shown to be the best measures of behavioural inhibition in Study 1B (i.e., the Stop-Signal task, Go / No-go task and Sustained Attention to Response task). Children with ADHD were aged from seven to 11 years, and were tested both when they had, and had not taken their regularly prescribed stimulant medication. The performance of children with ADHD on these tasks was compared to that of normally developing children matched in age. The results of Study 2 suggested that stimulant medication leads to significant improvement in behavioral inhibition amongst children with ADHD, such that children with ADHD do not differ from matched controls. However, this effect was not observed across all three tasks. Reasons for this, along with study limitations, and directions for future research are discussed.

Attention-Deficit / Hyperactivity Disorder (ADHD) is characterized by higher than normal levels of inattention, hyperactivity and impulsivity. Behavioural inhibition is proposed to be a primary deficit in children with ADHD, and is included as a component of a number of models accounting for the core behavioural symptoms of ADHD. Children with ADHD often show deficits in their performance on behavioural inhibition tasks relative to typically developing children of the same age, although inconsistent findings have been observed. Stimulant medication is associated with reduction in the core symptoms of ADHD in the majority of children. The primary goal of this thesis was to examine the effects of stimulant medication on behavioural inhibition in children with ADHD. Furthermore, this thesis sought to determine whether children with ADHD who have, and have not taken stimulant medication differ from normally developing children in terms of behavioural inhibition. In order to achieve these aims, it was necessary to firstly determine which tasks provide the best measures of behavioural inhibition. While many tasks have been used to measure inhibitory control amongst children with ADHD, it was unclear from previous research which tasks measure the same constructs. Study 1 investigated relationships in task performance among seven measures of inhibitory control, including the Stop-Signal task, Go / No-go task, Sustained Attention to Response Task (SART; analogous the not-X Continuous Performance Task), Eriksen Flanker task, Stroop, Opposite Worlds task and Task-Switching task. Significant developmental changes in a variety of cognitive abilities occur across childhood and adolescence. To limit the possibility that developmental changes in task performance would be observed, the age range for children included in the study was restricted to seven to 10 years. Nevertheless, to interpret correlations among inhibition measures from the tasks, it was necessary to determine whether children showed comparable developmental trends in their performance across tasks. Study 1A investigated developmental changes in the performances of the seven tasks purported to measure inhibitory control in normally developing children aged seven to 10 years. The results of this study suggested that the tasks chosen were appropriate for use among this age group, and that there is little change in behavioural inhibition across the seven to 10 years age range. In Study 1B, inhibition measures from each of the tasks were included in an exploratory factor analysis to determine those tasks measuring the same constructs. The results of Study 1B suggested that the Stop-Signal, Go / No-go and SART tasks provided the best measures of the behavioural inhibition construct. Performance on the Eriksen Flanker task was also related to the performance on these tasks, but in a direction contrary to that predicted. The Stroop and Opposite Worlds tasks measured the same construct, which appeared to be interference control. Performance on the Task-Switching task was not related to the performance on any other task, suggesting that this task did not measure behavioural inhibition or interference control. Study 2 investigated the performance of children with ADHD on the three tasks shown to be the best measures of behavioural inhibition in Study 1B (i.e., the Stop-Signal task, Go / No-go task and Sustained Attention to Response task). Children with ADHD were aged from seven to 11 years, and were tested both when they had, and had not taken their regularly prescribed stimulant medication. The performance of children with ADHD on these tasks was compared to that of normally developing children matched in age. The results of Study 2 suggested that stimulant medication leads to significant improvement in behavioral inhibition amongst children with ADHD, such that children with ADHD do not differ from matched controls. However, this effect was not observed across all three tasks. Reasons for this, along with study limitations, and directions for future research are discussed.

This study recorded Event Related Potentials (ERPs) during completion of a Continuous Performance Task (CPT) in order to identify the contribution of response inhibition, working memory, and response monitoring to the pattern of hyperactive and impulsive and inattentive behaviour observed in patients with Attention Deficit Hyperactive Disorder (ADHD). Four ERP components, Nogo N2, Nogo P3, Go P3, and the ERN were examined and compared using a symptomatic and asymptomatic ADHD sample, and a healthy control group. The Nogo N2 had the expected frontal scalp distribution and was affected by changes to inhibitory demands. It was also suggested that this component was not wholly determined by inhibitory processing and may have been influenced by differing presentation rates of the Go stimulus, a template matching process or an in-depth response strategy. Source localisation analysis suggested a right frontal generator for this component. The Nogo P3 had the expected central distribution and had equal amplitude for those participants that were more efficient at inhibiting behaviours compared to those participants that were less efficient inhibitors. Contrary to expectations, the Nogo P3 was not affected by increasing the inhibitory demands of the task and was suggested as being a less reliable indicator of response inhibition in the present study. The Go P3 had the expected centro-parietal distribution, and appeared to provide a reliable index of working memory. Response inhibition and working memory were not impaired in the sample of symptomatic and asymptomatic ADHD adults used in this study. The symptomatic group elicited a slightly enhanced ERN compared to the asymptomatic and control groups, indicating that deficits in response monitoring may contribute to the pattern of problematic behaviour observed in people with ADHD.

Thesis (M.S. in psychology)--Washington State University, August 2009. / Title from PDF title page (viewed on July 15, 2009). "Department of Psychology." Includes bibliographical references (p. 27-31).

Thesis (PhD) - Faculty of Life and Social Sciences, Swinburne University of Technology, 2009. / Submitted in fulfillment of the requirements for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2009. Typescript. Includes bibliographical references (p. 264-308)

Thesis (M.I.T.)--The Evergreen State College, 2010. / Title from title screen (viewed 7/7/2010). Includes bibliographical references (leaves [116]-120).

Thesis (Ph. D.)--Illinois State University, 2000. / Title from title page screen, viewed July 31, 2006. Dissertation Committee: Steven Landau (chair), Jeffrey Kahn, Becky Ladd, Vicky Morgan, David Barone. Includes bibliographical references (leaves 87-93) and abstract. Also available in print.