Gail Tripp

Self-Report of ADHD Symptoms in University Students Cross-Gender and Cross-National Prevalence

Little research has examined the structure and prevalence of attention-deficit/hyperactivity disorder (ADHD) symptoms in university students, including whether symptom structure conforms to the bidimensional (i.e., inattention and hyperactivity-impulsivity) conceptualization of the Diagnostic and Statistical Manual of Mental Disorders (DSMV-IV; American Psychiatric Association, 1994) and whether self-reported symptoms vary across gender and country. A sample of 1,209 university students from three countries (Italy, New Zealand, and the United States) completed a 24-item self-report measure (the Young Adult Rating Scale) tapping ADHD symptomatology. Factor analyses within the U.S. and New Zealand samples supported a bidimensional symptom structure, whereas weaker support for this conceptualization was provided by the Italian sample. Participants did not vary significantly by gender in symptom report; however, Italian students reported significantly more inattention and hyperactivity-impulsivity symptoms than students from the United States, and students from New Zealand reported more inattention symptoms than students from the United States. The prevalence of self-reported ADHD symptoms beyond DSM-IV thresholds for diagnosis ranged from 0% (Italian women) to 8.1% (New Zealand men). The implications of these results for the use of DSM-IV criteria in identifying university students with ADHD are discussed.

Neurobiology of ADHD

Attention-deficit hyperactivity disorder (ADHD) is a prevalent and debilitating disorder diagnosed on the basis of persistent and developmentally-inappropriate levels of overactivity, inattention and impulsivity. The etiology and pathophysiology of ADHD is incompletely understood. There is evidence of a genetic basis for ADHD but it is likely to involve many genes of small individual effect. Differences in the dimensions of the frontal lobes, caudate nucleus, and cerebellar vermis have been demonstrated. Neuropsychological testing has revealed a number of well documented differences between children with and without ADHD. These occur in two main domains: executive function and motivation although neither of these is specific to ADHD. In view of the recent advances in the neurobiology of reinforcement, we concentrate in this review on altered reinforcement mechanisms. Among the motivational differences, many pieces of evidence indicate that an altered response to reinforcement may play a central role in the symptoms of ADHD. In particular, sensitivity to delay of reinforcement appears to be a reliable finding. We review neurobiological mechanisms of reinforcement and discuss how these may be altered in ADHD, with particular focus on the neurotransmitter dopamine and its actions at the cellular and systems level. We describe how dopamine cell firing activity is normally associated with reinforcing events, and transfers to earlier time-points in the behavioural sequence as reinforcement becomes more predictable. We discuss how a failure of this transfer may give rise to many symptoms of ADHD, and propose that methylphenidate might act to compensate for the proposed dopamine transfer deficit.

Identifying the neurobiology of altered reinforcement sensitivity in ADHD: A review and research agenda

ADHD is associated with altered reinforcement sensitivity, despite a number of inconsistent findings. This review focuses on the overlap and differences between seven neurobiologically valid models and lists 15 predictions assessing reinforcement sensitivity in ADHD. When comparing the models it becomes clear that there are great differences in the level of explanation. For example, some models try to explain a single core deficit in terms lower-level reinforcement systems, such as the dopamine transfer to reward back in time. Other models explain multiple deficits, by describing higher-level systems, such as impaired bottom-up prefrontal activation. When reviewing the available experimental evidence in support of the predictions, most experimental studies have been focusing on behavioral changes in the face of reward and response cost over no-reward, and on delay discounting. There is currently a lack in studies that focus on explaining underlying cognitive or neural mechanisms of altered reinforcement sensitivity in ADHD. Additionally, there is a lack in studies that try to understand what subgroup of children with ADHD shows alterations in reinforcement sensitivity. The scarcity in studies testing the neurobiological predictions is explained partly by a lack in knowledge how to test some of these predictions in humans. Nevertheless, we believe that these predictions can serve as a useful guide to the systematic evaluation of altered reinforcement sensitivity in ADHD.

Sensitivity to Reward Delay in Children with Attention Deficit Hyperactivity Disorder (ADHD)

The present study compared the sensitivity to pre- and post-reward delays of children with and without DSM-IV combined type ADHD. Thirty-six children with DSM-IV combined type ADHD and 36 controls completed a signal-detection task. Correct identification of one stimulus produced an immediate reward and then a 3.5 s delay before the next trial (immediate reward). Correct identification of the other stimulus was associated with a 3.5 s delay before reward was delivered (delayed reward). Group differences emerged in response bias toward the immediately rewarded alternative. Children in the ADHD group showed a greater bias toward immediate reward than the controls. Children in the control group showed different patterns of response bias and discriminability following immediate and delayed rewards. For these children discriminability was lower and response bias was greater on trials following delayed reward. Both groups responded more slowly on trials following delayed reward. These findings support the hypothesis that children with ADHD are unusually sensitive to pre-reward delays.

Parent and teacher rating scales in the evaluation of attention-deficit hyperactivity disorder : Contribution to diagnosis and differential diagnosis in clinically referred children

ABSTRACT. This study evaluated diagnostic utility of parent and teacher ratings in the attention-deficit hyperactivity disorder (ADHD) assessment and differential diagnosis of a clinical sample of children referred for suspected ADHD. Participants were 184 5- to 12-year-old children for whom the following were available: multimethod multi-informant assessment, firm decision regarding presence or absence of ADHD, and parent-completed Child Behavior Checklist and revised 48-item Conners Parent Rating Scale, and teacher-completed Teacher Report Form and 39-item Conners Teacher Rating Scale. Parent ratings of children diagnosed with and without ADHD were generally similar. In contrast, teachers rated students diagnosed with ADHD as displaying higher levels of behavioral difficulties. Discriminant function analyses indicated parent ratings of narrowband measures of ADHD and broadband measures of externalizing symptoms displayed high sensitivity. Teacher ratings outperformed parent ratings when considering sensitivity, specificity, and overall classification accuracy. For clinically recommended cut scores, teacher measures displayed good specificity and positive predictive power. Combining rating scales within informants. did not improve classification accuracy. Combining across parent and teacher measures produced results consistent with teacher ratings. Results support recommendations to include parent and teacher rating scales in ADHD assessment. Scales contributing most to classification accuracy were those designed to assess ADHD. Imperfect performance of rating scales supports recommendations to include other methodologies in diagnosis and differential diagnosis of ADHD.

Altered Functional Brain Connectivity in a Non-Clinical Sample of Young Adults with Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is characterized by symptoms of inattention and hyperactivity/impulsivity that often persist in adulthood. There is a growing consensus that ADHD is associated with abnormal function of diffuse brain networks, but such alterations remain poorly characterized. Using resting-state functional magnetic resonance imaging, we characterized multivariate (complex network measures), bivariate (network-based statistic), and univariate (regional homogeneity) properties of brain networks in a non-clinical, drug-naive sample of high-functioning young men and women with ADHD (nine males, seven females) and a group of matched healthy controls. Data from our sample allowed the isolation of intrinsic functional connectivity alterations specific to ADHD diagnosis and symptoms that are not related to developmental delays, general cognitive dysfunction, or history of medication use. Multivariate results suggested that frontal, temporal, and occipital cortices were abnormally connected locally as well as with the rest of the brain in individuals with ADHD. Results from the network-based statistic support and extend multivariate results by isolating two brain networks comprising regions between which inter-regional connectivity was significantly altered in the ADHD group; namely, a frontal amygdala-occipital network and a frontal temporal-occipital network. Brain behavior correlations further highlighted the key role of altered orbitofrontal-temporal and frontal-amygdala connectivity for symptoms of inattention and hyperactivity/impulsivity. All univariate properties were similar between groups. Taken together, results from this study show that the diagnosis and the two main symptom dimensions of ADHD are related to altered intrinsic connectivity in orbitofrontal-temporal-occipital and fronto-amygdala-occipital networks. Accordingly, our findings highlight the importance of extending the conceptualization of ADHD beyond segregated fronto-striatal alterations.

DSM-IV and ICD-10: A Comparison of the Correlates of ADHD and Hyperkinetic Disorder

OBJECTIVE To examine directly the extent to which ICD-10 hyperkinetic disorder and DSM-IV attention-deficit/hyperactivity disorder (ADHD) identify the same children with the same difficulties. METHOD Participants were children referred for symptoms of overactivity, inattention, and impulsivity, and a normal control group. Diagnostic criteria for ICD-10 hyperkinetic disorder and DSM-IV ADHD were applied retrospectively. Four groups were identified: hyperkinetic disorder and ADHD (n = 21), ADHD only (n = 22), clinic control (n = 15), and normal control (n = 19). The groups were compared on measures reflecting the central characteristics of ADHD, neurodevelopmental functioning, academic and cognitive functioning, and the presence of conduct problems. RESULTS There is some evidence of increased symptom severity in the combined diagnostic group. Few differences emerged on measures of neurodevelopmental, academic, and cognitive functioning. Rates of conduct disturbance were similar in both ADHD groups. CONCLUSIONS DSM-IV criteria identify a broader group of children than those identified by ICD-10. However, there is substantial overlap between the groups formed with these different criteria.

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.

Parent Stress Management Training for Attention-Deficit/Hyperactivity Disorder.

This study assessed the effectiveness of a targeted 9-week parent stress management program (PSM) on the parenting stress, mood, family functioning, parenting style, locus of control, and perceived social support of parents of children diagnosed with DSM-IV ADHD. Sixty-three parents from 42 families were randomly assigned to 1 of 2 conditions: immediate treatment or wait-list control. Results of the randomized control trial showed that for mothers, completion of the PSM program was accompanied by significant reductions in parent-domain parenting stress together with significant improvements in parenting style (verbosity, laxness, overreactivity). For fathers, completion of the program was associated with a reduction in verbosity only. Anonymously completed consumer satisfaction questionnaires demonstrated a high degree of satisfaction with the PSM program.

Student note-taking related to university examination performance

Student note-taking is an almost universal activity among university students, yet few naturalistic studies have examined relationships between note-taking practices and subsequent examination performance. Complete sets of notes on an introductory psychology course, involving 75 lectures presented by ten instructors, were obtained from nineteen male and nineteen female students. Notes on ten selected lectures (one per instructor) were analysed, and information derived about class attendance and the quantity, organization, and presentation of the notes. Variables based on this information were then correlated with performance on two three-hour final examination papers (one multiple-choice, one essay). High correlations were found between the quantity of notes and examination performance. Surprisingly, these correlations increased in subsamples consisting of those students who attended class most diligently. The correlations involving the multiple-choice examination tended to be higher than those involving the essay examination, most probably because of wider sampling of lecture content and a more factual orientation in the multiple-choice examination. The results appear to conflict with the advice given in student study guides, many of which suggest that students should be very selective and concise in their note-taking.