Task 1 - Trapping Pen & Wobbly Legs PDF

Task 1 - Trapping pen and wobbly legs Learning goals What are the symptoms and prevalence of ADHD (DSM-5)? What are the causes of ADHD? What are the treatments of ADHD and how efficacious are they? What are similar disorders to ADHD and comorbidities?...

Task 1 - Trapping pen and wobbly legs Learning goals What are the symptoms and prevalence of ADHD (DSM-5)? What are the causes of ADHD? What are the treatments of ADHD and how efficacious are they? What are similar disorders to ADHD and comorbidities? Introductory chapters Attention deficit hyperactivity disorder (ADHD) - a persistent pattern of inattention and/or hyperactivity-impulsivity that is at a significantly higher rate than would be expected for the child at that developmental stage. ADHD can manifest itself behaviorally in many ways: lack of attention in academic, occupational or social situations, making careless mistakes in school work or other tasks, difficulty maintaining attention until task completion, appearing to have attention elsewhere and failing to take in/respond to instructions, and a tendency to shift from one task to another without completing any of them. The child with ADHD typically has a strong dislike for tasks that require sustained effort and attention over a long period of time, and is easily distracted by irrelevant stimuli/events. Hyperactivity may be manifest as excessive fidgetiness and not remaining seated when asked. Children with ADHD show excessive running/climbing when inappropriate, or talk excessively. ○ Infants with ADHD are constantly 'on the go', jumping and climbing on furniture, and have difficulty in sedentary activities (e.g. listening to a story). Impulsivity manifests as impatience and constantly interrupting others before they have finished what they have to say. ○ It may also reflect a desire for immediate over delayed rewards. ○ It may result in accidents or indulging in dangerous activities. The diagnosis of ADHD Most individuals with ADHD have symptoms of both inattention and hyperactivity but in some people one of these patterns is more dominant. This resulted in 2 diagnostic subtypes: ADHD, predominantly inattentive presentation. - if only criterion inattention is met in the past 6 months ADHD, predominantly hyperactive/impulsive presentation - if only criterion hyperactivity- impulsivity is met for the past 6 months. Combined presentation - if both inattentive and hyperactive/impulsive elements have been present for the last 6 months. 50% of those diagnosed with the combined presentation will also be diagnosed with oppositional defiant (conduct) disorder. This is the highest comorbidity for ADHD. This indicates that ADHD is often associated with the violation of social norms and the basic rights of others. When a child is diagnosed with both ADHD and conduct disorder, it usually shows the worst of both disorders. Children with a single ADHD diagnosis have a better long-term prognosis than those with conduct disorder and ADHD. Childhood ADHD does not predict antisocial personality disorder differentially in adulthood. ▪ However, there is evidence that sometimes ADHD can lead to an earlier onset of conduct disorder. This may be because some children with ADHD suffer from an escalation of symptoms caused by a vicious cycle of their disruptive behavior evoking aggressive reactions, which in turn evokes aggressive & increasingly antisocial reactions in the sufferer. 45-60% of children with ADHD develop a conduct disorder, abuse drugs or alcohol, or violate the law. Anxiety and depression are comorbid in a minority of children with ADHD. ADHD is usually first recognized and diagnosed when school begins because learning & adjustment at school is significantly affected by the disorder. As the child develops into adolescence, symptoms usually decrease. However, about 50% continue to show symptoms well into adulthood, which may affect intellectual functioning and IQ negatively. Adults diagnosed with ADHD are at increased risk for antisocial personality disorder, substance abuse, mood and anxiety disorders, marital problems, traffic accidents and frequent job changes. Some adults who have had lifelong problems achieving success in school and at work and difficulties in social relationships may have had undiagnosed and untreated ADHD as children. Psychopathology Page 1  undiagnosed and untreated ADHD as children. ADHD may be a culturally constructed disorder to some extent, but evidence is mixed. Study: detection of externalizing disorders is lower in a sample of non-Dutch parents (Moroccan, Turkish, Surinamese) than Dutch parents. Cultural contexts may have an impact on whether ADHD symptoms are detected and reported. However, some studies have found very similar rates of diagnosis across different culture and ethnic groups. The prevalence of ADHD 5% of school- & pre-school-age children and 2.5% of adults worldwide are diagnosed with ADHD. ADHD has been suggested to be more common in boys than girls. However, this may be because boys are more likely to be referred for treatment than girls. Girls with ADHD tend to show mostly inattentive features and have less disruptive behaviors than boys, which may lead to an underdiagnosis of ADHD in girls. Some have suggested that ADHD symptoms are not sex-specific, but identification of girls with ADHD has been hampered by parental and teacher bias. Any sex differences found with ADHD in childhood do not appear to be found in late adolescence or adulthood where male & female prevalence rates are the same. The consequences of ADHD Attentional deficits & hyperactivity may make ADHD individuals prone to temper outbursts, frustration, bossiness, stubbornness, changeable moods and poor self-esteem. As a result, academic achievement is usually impaired leading to conflict with teachers and family. Family members often view the behavior of ADHD children as intentional and irresponsible, which may cause resentment within the family. 20-25% of children with ADHD may have a specific learning disorder that makes it even harder to concentrate in school and learn. Individuals with predominantly inattentive symptoms tend to suffer most in terms of academic achievement. Hyperactivity and impulsivity are associated with peer rejection and accidental injury. In general, children with ADHD have great difficulty making friends and integrating successfully into social groups. In new social settings, children with ADHD are often rejected rapidly by their peers. They want to play by their own rules, and when things do not go their way, they may become aggressive. This is due to their disruptive behaviors, but also because they fail to understand the intentions of their peers and are unable to translate the correct social response into appropriate behavior. In adulthood, ADHD is associated with success & safety at work, poorer interpersonal relationships, poorer academic outcomes, and poorer general life satisfaction. The etiology of ADHD The current view is that biological factors are particularly important in the etiology of ADHD, especially inherited ones that may strongly mediate susceptibility to ADHD. Biological factors Average heritability of ADHD from twin studies is 76%. Several genes have been found that may cause ADHD, but they have a very small individual effect. Many of them may underlie abnormalities in the dopamine, norepinephrine and serotonin systems. Specific genes that may be involved are the dopamine transported gene, the dopamine D4 & D5 receptors and SNAP-25, a gene that controls the way dopamine is released in the brain. A gene-environment interaction is suggested to cause ADHD. ADHD susceptibility is inherited, but ADHD becomes manifest only when certain environmental influences are found. Study: children with 2 copies of the 10-repeat allele of a DAT1 gene (related to dopamine regulation) who were exposed to maternal prenatal smoking showed significantly higher levels of hyperactivity, impulsiveness and oppositional behaviors than a control group of children who had the same genes but whose mothers did not smoke during pregnancy. Children who had only 1 of the 2 risk factors (genotype or a smoking mother) did not show significantly higher levels of ADHD symptoms than children who possessed neither of the risk factors. Other environmental risk factors include pre- or perinatal complications, maternal drinking during pregnancy, general birth complications (e.g. low birth weight, respiratory distress and birth asphyxia), lead levels in the blood and chronic exposure to nicotine or tobacco smoke. Study: 22% of mothers of children with ADHD reported smoking a pack of cigarettes a day compared with only 8% of mothers whose children did not develop ADHD. Prenatal exposure to nicotine may cause abnormalities in the dopaminergic system, resulting in difficulties inhibiting behavior. The brains of children with ADHD are smaller (by 3.2%) than those of healthy controls, and have less grey matter. The frontal cortex (important for executive functioning), basal ganglia and the cerebellum (influencing the cortico-striatal-thalamo-cortical circuits important in choosing, initiating and carrying out complex motor and cognitive responses) show abnormalities in children with ADHD. In children with ADHD, there is less connectivity between frontal areas and brain areas that influence motor behavior, memory, attention and emotional reactions. Neurological immaturity hypothesis - the brains of children with ADHD develop more slowly, leaving them unable to maintain attention and control their behavior at an age-appropriate level. The median age by which 50% of the cortex reaches peak thickness is 10.5 in children with ADHD but only 7.5 years in normally developing controls. In some children the symptoms of ADHD, especially hyperactivity symptoms, decline with age. Psychopathology Page 2  In some children the symptoms of ADHD, especially hyperactivity symptoms, decline with age. Psychological factors Children with ADHD are more likely to be brought up by parents who also have the disorder, which may exacerbate any symptoms that are caused by the genetic component alone. Fathers who are diagnosed with ADHD have been found to be less effective parents (e.g. they exhibit ineffective discipline) than parents without an ADHD diagnosis. This may exacerbate any disruptive characteristics the ADHD child may exhibit. Psychodynamic approaches have suggested that ADHD results when a predisposition is accompanied by authoritarian parenting methods, because such parents are likely to become impatient with a disruptive & hyperactive child, resulting in a vicious cycle of attempts to discipline a child that cause even more defiant reactions. Learning theorists have suggested that when ADHD children are impulsive & disruptive, the attention from the parent (who attempts to control the child) reinforces these behaviors, increasing their frequency and intensity. Time-out from positive reinforcement can reduce negative and disruptive behavior in children with ADHD. Evidence on the relationship between ADHD and theory of mind skills is mixed. Children with ADHD show impaired performance on executive functioning tasks, especially on tasks requiring planning and inhibition of behavior. This is consistent with evidence that shows abnormalities in the frontal lobes in children with ADHD. Cognitive tests of ADHD Treatments of ADHD 70-85% of ADHD children respond to stimulant drugs, such as Ritalin, Dexedrine and Adderall with decreases in demanding, disruptive and noncompliant behavior. The drugs also lead to increase in positive mood, goal-directedness, and quality of interactions with others. The stimulants increase dopamine in the synapses, and enhance release & inhibit reuptake of serotonin. Side effects include reduced appetite, insomnia, edginess, gastrointestinal upset, increased tic frequency, decrease in growth rate. Drugs that affect norepinephrine levels (atomoxetine, clonidine, guanfacine) can help reduce tics, common in children with ADHD and increase cognitive performance. Side effects include dry mouth, fatigue, dizziness, constipation, and sedation. Antidepressants are sometimes prescribed to children & adolescents with ADHD (especially if they also have depression). Antidepressants increase cognitive performance, but are not as effective for ADHD as stimulants. The gains made by ADHD children with drugs alone are short-term and symptoms often return as soon as medication is stopped. Behavioral therapies for ADHD focus on reinforcing attentive, goal-directed, and prosocial behaviors and extinguishing impulsive & hyperactive ones. They typically engage parents & teachers in changing rewards and punishments in many aspects of the child's life (e.g. a child and her parents may agree that she gets a chip every time she obeys a request to wash her hands, and the chips can be exchanged for fun activities at the end of the week; refusing to comply results in losing a chip). Children learn to anticipate the consequences of their behaviors and to make less impulsive choices. Psychopathology Page 3  Children learn to anticipate the consequences of their behaviors and to make less impulsive choices. Behavioral therapy is highly effective in reducing symptoms of ADHD in children. For adults, cognitive-behavioral treatments that include organizational, planning, and time management skills are also effective. Combining stimulant & psychosocial therapy is more likely to produce short-term improvements than either therapy alone. However, after a longer period (e.g. a few years later), the differences between drugs + behavioral therapy, drugs, and therapy are not significant. Treatment strategies for ADHD: an evidence-based guide to select optimal treatment - Caye Article Non-pharmacological interventions (e.g. cognitive training & neurofeedback) are probably not efficacious and more research is needed to support/refute the role of behavioral therapies in ADHD treatment. Pharmacological treatment The most widely used medications are psychostimulants - methylphenidate (MPH) and amphetamines (AMP). Second-line medications include atomoxetine (ATX), guanfacine (GFC), and clonidine (CLO), usually prescribed after no response, intolerance, or contraindication to the psychostimulants. Mechanisms of action of medications for ADHD treatment Most medications for ADHD act primarily on catecholamine pathways, by increasing the availability of dopamine or norepinephrine in synapses. Recent PET studies suggest that the density of dopamine transporters increases and becomes high after chronic treatment with stimulants. Psychostimulants (MPH & AMP) inhibit dopamine and norepinephrine transporters, thus inhibiting reuptake, increasing neurotransmission primarily in the striatum and PFC. ATX inhibits the norepinephrine transporter 1 (NET 1), preventing reuptake in all brain regions and of dopamine in the PFC. CLO and GFC are alpha-2 receptor agonists, which stimulate alpha-2 noradrenaline receptors in the CNS. This helps ADHD by e.g. increasing noradrenergic activity in the PFC. The mechanisms of action mentioned above are reductionist and incomplete. The immediate effects on dopaminergic & noradrenergic neurotransmission can explain improved cognitive functions that are controlled by affected brain circuits (e.g. executive functioning, response to reward, memory etc.). However, other aspects of treatment cannot be explained, e.g. differences in the delay for onset & offset in efficacy, which may be hours for stimulants and weeks-months for non-stimulants. A plausible hypothesis is that some ADHD medications may promote long-term brain alterations by regulating genes & proteins involved in neural growth & configuration of receptors & transporters. Pharmacogenomics of medication for ADHD 1/3 of patients do not respond adequately to and/or tolerate stimulant treatment. This may be explained with genetic factors: SNPs at certain genes and variable numbers of tandem repeats in DRD4 & SLC6A3 genes have been found to be associated with response to stimulant treatment. However, this research is still at early stages and is only clinically applicable to special cases. Evidence of efficacy Psychostimulants are the most effective available treatment for ADHD, at least in the short-term, with clear acute benefits (within an hour after an adequate dose) that continue until the drug is metabolized. If medication is continued, these acute benefits persist for at least a year (but dose increases may be necessary to maintain full efficacy). Stimulants are safe and well-tolerated. Reviews and meta-analyses claim that the randomized control trials on average had low quality. ATX is prescribed when psychostimulants are contraindicated/not tolerated. It is especially useful when ADHD is comorbid with other disorders that can be exacerbated by stimulants (e.g. bipolar disorder, Tourette's, substance abuse) ATX has acceptable efficacy and tolerability, but the effect size is smaller than psychostimulants. CLO has a weaker effect than psychostimulants and is rarely prescribed as a standalone treatment (due to a short duration of action and adverse effects). In some countries it is used as an add-on treatment with stimulants. GFC has a weaker effect than stimulants and its strength is comparable to ATX. It is useful as an additional treatment to stimulants. Nonpharmacological treatments Behavioral and psychosocial treatments Behavior parent training and social skills training are regarded as first-line treatments for very young children or those with mild-moderate ADHD. They are also the standard add-on treatment for severe presentations at any age. Most guidelines recommend behavioral interventions for ADHD in any situation, alone or combined with medication. The evidence for behavioral interventions' efficacy on core ADHD symptoms is conflicting and difficult to integrate. It is possible that not all patients are suitable for receiving each of the behavioral interventions, which may explain some of the controversial findings. However, evidence is clear that they are effective at improving parenting, parent-child relationships and oppositional behaviors that are common in children with ADHD and their families. Cognitive training Psychopathology Page 4 Cognitive training Cognitive training strategies aim to reduce ADHD symptoms by training ADHD-related neuropsychological skills (e.g. attention, inhibition, WM). Cognitive training programs are usually delivered through computers or mobile devices. Evidence so far suggests that cognitive training has moderate effect on improving the targeted neuropsychological functions, but has no effect on core ADHD symptoms or other functional outcomes for ADHD patients. Neurofeedback Neurofeedback - the patient is trained to improve self-control over brain activity patterns, which is most often monitored through simultaneously collected EEG data. ADHD patients show distinct EEG patterns compared to their non-affected peers. Current neurofeedback protocols focus on increasing theta waves (related to decrease vigilance) and/or increasing beta waves (related to concentration & neuronal excitability). This works by measuring EEG while the patient is doing a task (e.g. computer game), and modulates performance and reward according to specific changes in EEG patterns. Evidence suggests that neurofeedback may have moderate effect on ADHD symptoms. These results are still inconclusive due to low-quality studies and non-blinded raters. Neurofeedback is a specialized intervention, requiring 20-40 sessions, which is often expensive for the patient. Dietary modifications Removing artificial food colors (AFC) from diet continuously or restricting several foods in a rapid course of 9-28 days (few foods approach - FFD) have significant, but clinically small effects on ADHD symptoms. Impact of treatment in real-life outcomes Patients with ADHD who receive treatment have better long-term outcomes than their non-treated counterparts across most studied domains. The effect is higher for combined pharmacological & nonpharmacological treatment than for either of these alone. Selection of treatment The clinician input The patient/caregiver input Patients and caregivers often show preconceived treatment preferences closely related to their sociocultural context. Parents with higher education more often see ADHD as a biomedical illness, which increases their likelihood of accepting medication. Parents often prefer trying medication, while children often do not want to take the medication due to complex factors (e.g. social stigma, side effects, not appreciating the benefits of treatment). Monitoring, follow up, and continued care Monitoring patient improvement by using rating symptom scales in each visit increases positive clinical outcomes and chance of remission. Implementing a carefully constructed medication protocol with a routine measure of standardized outcomes can result in significant improvements in clinical outcomes and that these can be sustained over long periods of time. ADHD is a chronic disorder and when treatment is stopped, the associated benefits tend to reduce until they disappear. Computerized Training of Working Memory in Children With ADHD - A Randomized, Controlled Trial - Klingberg Article This study investigates if systematic training of WM tasks during a 5-week period improves WM and executive functions and reduces ADHD symptoms. Method Participants Psychopathology Page 5 Participants Only nonmedicated children participated so that there is more room for clinical improvement of ADHD symptoms. The participants had ADHD of either combined or predominantly inattentive subtype. Outcome measures The span-board task was used to measure visuospatial WM (main outcome measure, because it was not a practiced measure of visuospatial WM during the treatment). Digit span was used to measure verbal WM. Stroop interference task was used to measure response inhibition. Raven's colored progressive matrices was used to measure nonverbal reasoning ability. Motor activity was measured using an infrared camera that records number of head movements during 15 minutes of performance of a detection task on a computer. ADHD symptoms were measured using the 18 DSM-IV items as a rating scale + the Conners Rating Scale for parents and teachers. Intervention Treatment condition - children perform WM tasks implemented in a computer program, which was used at home or in school. The program included visuospatial and verbal WM tasks. Children perform 90 WM trials on each day of training. Medium total training time is about 40 minutes. Difficulty level is automatically adjusted on a trial-by-trial basis to match the WM span of the child on each task. Comparison condition - the same tasks are used, but the WM load is low, thus resulting in easy tasks that are expected to result in only small training effects. Everything is identical to the treatment condition, except that the difficulty of the 90 WM trials remained on the initial low level, instead of being increased to match the WM span of the child. Results The postintervention visit (T2) took place 5-6 weeks after the baseline visit (T1). The follow-up assessment (T3) was done 3 months after T2. There was a significant improvement for all executive tasks at period T2. At follow-up (T3), the performance in the treatment group was as high as, or higher than at post-intervention (T2). All significant differences remained significant when ADHD subtype was also included in the analyses. There was a significant reduction in the inattention and hyperactivity - impulsivity ratings of parents, but not of teachers. Discussion The improvement on the span-board task is evidence that the training effect generalized to a nontrained visuospatial WM task. The effect of training on visuospatial WM was comparable with that of medication. The authors suggest that computerized training of WM may be a promising intervention for children with ADHD, but further research is needed to determine the long-term effects and generalizability of the training (article is from 2005). Does Computerized Working Memory Training with Game Elements Enhance Motivation and Training Efficacy in Children with ADHD? - Prins Article Introduction Psychopathology Page 6 2 theoretical approaches to childhood ADHD: it is caused by executive functioning deficits or motivational variables. Barkley's theory (executive functioning approach) - self-regulation deficits are the core of ADHD, and they are related to executive functions. Visuospatial WM is considered the most important neuropsychological deficit in children with ADHD. Motivational approach - ADHD results from an abnormal sensitivity to reinforcement. The high intensity of reinforcement increases task performance and motivation. This effect is more pronounced in ADHD children, which prefer immediate over delayed reward. An unusually low level of intrinsic motivation may account for the performance deficits in children with ADHD (therefore when tasks are boring or when there is no supervision, their attention span is very limited). Cognitive-energetic model (CEM) - information processing is influenced by both computational (process) factors and state factors (e.g. effort, arousal, and activation). If children with ADHD suffer from a deficit in effort (the energy needed to meet task demands, related to motivation), poor performance may result from a non-optimal energetic state. Therefore, if state factors are manipulated, increased effort may result in cortical stimulation and thus performance improvements. Computer-assisted instruction (CAI) programs increase ADHD children's interest and motivation, because they provide clear goals, highlight important material and provide immediate feedback. Children with ADHD, while playing a computer game, can sustain attention for longer periods of time, and behave less impulsively. Therefore, CAI that have a game-like format may be more effective. Tasks with a game format may promote cognitive performance (compared to boring experimental tests) in children with ADHD by providing external motivating contingencies just before and at the moment of responding. They should also increase the arousal state, which may further promote optimal performance. The present study examines the value of adding game elements to standard computerized WM training without game elements on motivation, training performance and WM. Hypotheses: children in the WM game training will spend more time in training (motivation), reproduce more training sequences, make fewer errors (performance), and show greater effects on a WM task (training efficacy), compared with children in the standard computerized WM training condition. Method Corsi Block-tapping test (CBTT) - 9 cubes are placed on a square board. The blocks, numbered 1-9, are visible for the test leader only. The test leader taps a sequence of block (starting with 3 blocks) and the child must repeat 3 times in the correct order. If the child reproduces at least 1 of 3 sequences, the sequence is extended with 1 block up to a maximum of 8 blocks. After 3 successive errors within the same sequence length, the test is stopped. The memory span of the child is considered to be the last sequence length in which the child has reproduced >=2 sequences correctly. This was the main outcome measure of the study. Motivation level was assessed with the time the child used the training, absence time (average time that children were not using the mouse), number of sequences performed during training (objectively) and by asking children questions about the tasks, e.g. how boring, easy it is (subjectively). Control training - uses a task very similar to the CBTT, where squares light up in random order and the child needs to repeat the sequence. Game training - uses a similar task, in which participants need to reproduce sequences of randomly lit-up squares in a 4x4 grid. However, some elements are added: animations, a narrative, a goal, rewards, competition and identification (with a game character). Training sessions were held weekly for 3 consecutive weeks. Results Motivation More absence time was found in the control condition than in the game condition. Children in the control condition did not use the training for 42% of the time compared with 9% in the game condition. More sequences were performed in the game condition than in the control condition. Children in the game condition liked the task significantly more and would like to have the task at home. Training performance Significantly fewer incorrect sequences were reproduced in the gaming condition. Training efficacy Memory span in the game condition significantly increased from pre- to post-test, while no significant increase was found in the control condition. The group differences remain significant even when the number of performed sequences are taken into account. Discussion Children who trained on the game version of a visuospatial WM task were more strongly motivated to do the training (reduced absence time during the training and a greater number of trials completed), did better during training (fewer incorrect trials), and significantly improved after training on an untrained WM task (i.e., the CBTT), while no such improvement was observed for the control group. Training in a game environment may directly enhance the effect of WM training, rather than just enhance the amount of training, because even when controlling for number of sequences, the effect (game training superior to control training) is still there. Training and transfer effects of executive functions in preschool children - Thorell Article Psychopathology Page 7 Introduction At least 3 types of effects can be found for different cognitive training programs: Practice effects on the tasks included in the training program. Training effects on non-trained tasks measuring the particular cognitive aspect targeted by the training program. Transfer effects that generalize to either related cognitive constructs (i.e. WM training having effect on inhibition) or behaviors associated with the trained construct (i.e. cognitive training having effect on symptoms of attention, problem solving or school performance). The present study investigates the effects of 2 specific training programs focusing either on visuospatial WM or inhibitory control in preschool children. The WM training program includes only visuospatial WM tasks, because visuospatial WM is more clearly associated with ADHD compared to verbal WM. The inhibition training program included 3 different task paradigms, related to 3 types on inhibitory function associated with ADHD. Hypothesis: both training programs will have effects on the trained construct, and will show transfer effects to the other, because WM and inhibition have been shown to be related (e.g. they activate overlapping areas in the VLPFC). Hypothesis: both training programs will show transfer effects to attention because performance on both WM and inhibitory tasks requires continuous attention. Methods Healthy (no ADHD) preschool children between the ages of 4 and 5 years are split into 4 groups. All groups (except the passive control group) play computer games for 15 minutes each day after school during 5 weeks. WM training group - games are designed to improve visuospatial WM. Inhibition training group - games are designed to improve inhibitory control. Active control group - commercially available games are selected on the basis of their low impact on visuospatial WM and inhibitory control. Passive control group - no games are played; children only participate in pre- and posttesting. For the inhibition training, the following 3 tasks were used: Inhibition of a prepotent motor response (go/no-go paradigm). There were two go/no-go tasks in which the child was told to respond (‘go’) when a certain stimulus (e.g. a fruit) was presented, but to make no response (‘no-go’) when another stimulus (e.g. a fish) was presented Stopping of an ongoing response (stop-signal paradigm). There were also two versions of the stop-signal task in which the child was instructed to respond as quickly as possible when a stimulus (e.g. a fruit) was presented, except when that stimulus was followed by a stop-signal (e.g. a fish). Interference control - measured with the Flanker task, where 5 arrows pointing either right or left were presented in a row and the goal of the task was to make a response in accordance with the direction of the arrow in the middle (e.g. pressing a button to the right if the arrow was pointing to the right) while ignoring the arrows on the side. 8 pre- and posttest measures were used: Interference control was measured using a version of the Day-Night Stroop Task, which includes 2 pairs of opposites (day and night; boy and girl) and the child is instructed to say the opposite as quickly as possible when a picture is presented on the computer screen. Response inhibition was measured with number of commission errors on a go/no-go task (making a response when not instructed to do so). Visuospatial WM was measured with the Span board task. Verbal WM was measured with a word span task. Auditory attention was measured with an auditory continuous performance task (CPT). Visual attention was measured with the number of omission errors on a go/no-go task. Problem solving was measured with a Block Design test. Response speed was measured by the children's mean reaction time on correct responses on the go/no-go task. Results The children improved significantly on all trained tasks included Psychopathology Page 8  The children improved significantly on all trained tasks included in the WM training. For the inhibition training, the children had improved significantly on the go/no-go & Flanker tasks, but not on the stop-signal tasks. The improvement from day 1 to day 2 is excluded from analyses due to the steep increase. There were no significant differences between the active & passive control groups on any of the outcome measures, which is why they were combined in all further analyses. For both types of WM (verbal and visuospatial), the WM group, but not the inhibition group, showed significantly larger improvement over time compared to the control group. For the inhibitory control tasks, the training effects were not significant for either commission errors on the go/no-go task or for errors on the Stroop Task and all effects sizes for both training groups were small. A significant overall effect was, however, found for omission errors on the auditory CPT, as well as a marginally significant effect on omission errors on the go/no-go task. Planned comparisons revealed that the WM group, but not the inhibition group, had improved significantly more over time compared to the control group. Discussion The WM training had significant effects on non-trained verbal & spatial WM tasks, as well as significant transfer effects on laboratory measures of attention. The transfer of visuospatial WM training to the verbal domain of WM is consistent with neuroimaging findings showing evidence of parietal & prefrontal WM areas that are active irrespective of the type of stimuli being held in WM. On the other hand, training of inhibitory control did not have any significant effects relative to the control group, despite the fact that the children improved on at least some of the trained tasks. A modified version of the inhibitory training could have effects, but the results could also mean that cognitive functions differ in terms of how easily they can be trained. Psychological Heterogeneity in ADHD - a dual pathway model of behavior and cognition - Sonuga-Barke Article (2002) The article describes a study which provides evidence for a dual pathway model of ADHD combined type. Pathway 1 - ADHD is a disorder of dysregulation of thought and action associated with inhibitory control. Pathway 2 - ADHD is a motivational style (delay aversion) associated with fundamental differences in reward mechanisms. ADHD - deficient inhibitory control or delay aversion Neuropsychological evidence converges on the view that ADHD is associated with problems of executive functioning. A large number of studies using the stop signal paradigm (which tests an individual's ability to inhibit an already initiated pre-potent response to a 'go signal' when signaled to do so by a 'stop signal') support this view. Children with ADHD have a flatter probability of inhibition slope (given different stop intervals) and longer stop signal reaction times (SSRT). The association of ADHD with deficient inhibitory control seems more robust than that with other executive functions (e.g. WM). A number of alternative accounts have been proposed that emphasize the motivational basis of ADHD. Delay aversion hypothesis - ADHD behaviors are functional expressions of an underlying motivational style rather than the result of dysfunctional regulatory systems. According to this view, children with ADHD are motivated to escape or avoid delay. Therefore, their inattentive, overactive and impulsive behaviors are functional expressions of delay aversion. When faced with a choice between immediacy and delay, ADHD children will choose immediacy. For example, they prefer immediate over large delayed rewards under many circumstances. While this has been interpreted as deficient inhibitory control, there is evidence that the preference for immediacy is exerc ised only under certain conditions, and that preference for delayed rewards and inhibitory control are doubly dissociated. Psychopathology Page 9  under certain conditions, and that preference for delayed rewards and inhibitory control are doubly dissociated. When no choice is available, they will act on their environment to reduce their perception of time during delay by either creating or attending to non-temporal features of the environment. ADHD children's slower SSRTs might be due to the stop-signal paradigm's temporal structure, not necessarily indicative of inhibitory issues. The infrequent stop signals and differing inter-stimulus-interval (ISI) durations between go and stop signals could contribute to longer SSRTs. These ISI effects are common in ADHD children and can be attributed to state regulation problems or the influence of delayed attention, often seen as a form of delay aversion. It is also possible that worse inhibitory control leads to poor performance on tasks extended over time so that delay itself becomes associated with negative emotions and becomes aversive. Both of these explanations of the co-existence of delay aversion and inhibitory control problems would predict a high level of association between performance on the stop-signal paradigm and delay choice tasks. Delay aversion and poor inhibitory control 'head-to-head' A recent study compared the 2 opposing views using the most appropriate measure (according to experts endorsing each view) of the inhibitory control & delay aversion constructs. In this study, ADHD (combined) children and control children performed a standard stop signal task and a choice delay task, in which children choose between small immediate (1 point after 3 seconds) and large delayed (2 points after 30s) rewards. In the choice delay task, the response inhibition load should be trivial and no greater for a choice of the large delayed than the small immediate reward (receiving the large reward does not depend on inhibiting a response over the 30s delay period). Results of the study: Performance on the 2 tasks was not correlated. There was a large effect of ADHD on performance of both task, which was not altered when comorbidities were taken into consideration. A diagnostic procedure was developed using only the 2 measures. It correctly identified nearly 90% of the cases of ADHD. This suggests that ADHD is caused by 2 distinct processes - one underpinned by deficient inhibitory control and the other mediated by delay aversion. A dual pathway model of the development of ADHD The dual pathway of ADHD describes ADHD as a developmental outcome of 2 quite distinct psychological/developmental processes. The solid line represents the pathway for ADHD as a disorder of the regulation of thought and action. The dashed line representes ADHD as a motivational style. Inhibitory control is a primary psychological characteristic and cognitive & behavioral dysregulation are its secondary manifestations. Delay aversion is a secondary effect of a combination of fundamental changes to reward mechanisms and characteristics of the child's early environment. The dysregulation of thought and action pathway (DTAP - solid line) is characterized by a core dysfunction in inhibitory control. This causes both behavioral symptoms and poor quality task engagement. The emergence of ADHD symptoms is mediated by behavioral dysregulation, while the effects on task engagement are mediated by cognitive dysregulation. The model predicts also allows that there is a negative feedback loop from task engagement to executive function, which means that the reduction in the quantity of task engagement can eventually limit the opportunity for the development of higher order skills. The DTAP ADHD implicates frontal & prefrontal regions and their associated circuitry with projections from the basal ganglia as important. Functions facilitated by this circuit are regulated by dopamine activity as part of the meso-cortical branch of the dopamine system (meso-cortical = from the ventral tegmental area to the cortex). The motivational style pathway (MSP - dashed line) is a route from a shortened delayed gradient through acquired delay aversion to ADHD symptoms. ADHD children discount the value of future events at a higher rate than other children. This leads to a preference for immediacy (i.e. behavioral impulsiveness). The link between ADHD behaviors and altered reward mechanisms is mediated by the emergence over time of a generalized aversion to delay. This can be explained with classical conditioning: the shortened delayed reward gradient leads the child to repeatedly fail to effectively respond to contextual demands related to waiting and delay. This makes delay-rich settings acquire aversive properties through association with the negative emotions that come with such failure. Cultural practices have a moderating role on the effect of these altered reward mechanisms: parents who set unrealistically high standards and are Psychopathology Page 10  Cultural practices have a moderating role on the effect of these altered reward mechanisms: parents who set unrealistically high standards and are unforgiving of failures to wait are more likely to create the context for the emergence of delay aversion and ADHD in impulsive children. The MSP AD/HD is associated with alterations in brain reward circuits especially the ventral-striatal network (including the nucleus accumbens) associated with the meso-limbic branch (meso-limbic = from the ventral tegmental area to the ventral striatum) of the dopamine system. Distinctive features of the 2 pathways Both DTAP and MSP ADHD will met criteria for combined type ADHD diagnosis, but their symptoms are predicted to have distinct functional and structural properties. DTAP ADHD arises from dysfunction while MSP ADHD is a functional expression of a motivational style. Therefore, MSP ADHD is more likely to vary as a function of environmental context, while DTAP should be mostly context-independent. DTAP behavior is more likely to be seen as qualitatively different from normal child behavior. MSP children may be characterized as having an extreme expression of a normally distributed trait. DTAP ADHD should be associated with more severe and generalized cognitive impairment, because poor inhibitory control is compounded by the effects of behavioral symptoms on the child's opportunity to develop the ability to effectively provide, protect and utilize processing time. MSP ADHD children should not show deficits on tasks and functions that do not tap inter-temporal competencies. It is possible that due to their intact control systems, MSP children have the potential to adapt to the constraints on their performance by developing alternative information-processing strategies. The central role of classical conditioning in MSP opens up the possibility that ADHD is associated with environmental risks of a purely social nature rather than neurobiological ones. For example, delay aversion may arise when parents fail to follow through on promised rewards leading to a distrust of future events and an unwillingness to wait. Inflexible and demanding parenting, combined with unrealistically high expectations for self-control may predispose the emergence of delay aversion. If ADHD has developed in this situation, it should be amenable to psychosocial interventions. Concluding remarks DTAP is context independent, associated with relatively severe and generalized cognitive dysregulation, categorical in nature and less strongly associated with genetic factors. MSP is context dependent, has a more limited pattern of cognitive impairment associated with the provision, protection and utilization of time, is a continuously distributed trait and is more closely associated with genetic factors (why?) Beyond the dual pathway model: evidence for the dissociation of timing, inhibitory, and delay- related impairments in ADHD - Sonuga-Barke article (2010) The dual pathway model explains ADHD heterogeneity as 2 independent deficits, each affecting some ADHD patients: A deficit grounded in dorsal fronto-striatal dysregulation mediated by inhibitory executive dysfunction (I-EDF). A deficit underpinned by the ventral fronto-striatal circuits and linked to altered signaling of delayed rewards and delay aversion (DAv). However, many patients appear unaffected by either DAv or I-EDF. This article explores whether temporal processing deficits (TPD) in ADHD represent a dissociable 3rd neuropsychological pathway. Neuroimaging evidence shows that while TPD shares neural components (basal ganglia) with I-EDF and DAv, it is also distinctive in some ways (cerebellum). fMRI confirms alterations within key components of temporal processing circuits in ADHD. Children with ADHD have shown TPD across a range of timing tasks. Evidence of familial correlation and co-segregation has been reported for I-EDF, TPD and DAv (meaning that e.g. siblings of ADHD children with I-EDF should also show I-EDF). 3 tasks are chosen for each neuropsychological domain. The authors predict the following: Neuropsychological domains will form independent principal components. There will be significant case-control differences in each domain. Subgroups of ADHD individuals will be affected by only 1 deficit. There will be domain-specific familial effects. Neuropsychological domains will show distinctive patterns of association in terms of IQ and oppositional defiant disorder (ODD). Method 71 families with an ADHD child participated in 9 tasks (3 for each neuropsychological domain). I-EDF was measured with the stop-signal task, go/no-go task and the Stroop task. DAv was measured with the following tasks: Maudsley's Index of Childhood Delay Aversion (MIDA) - children choose to either wait 2s to shoot 1 spaceship (1 point) or to wait 30s to shoot 2 spaceships (2 points). Children are told that they will be given 1 or 2 rewards based on performance. Delay Frustration (DeFT) - 55 simple math questions are presented on a computer. On 8 trials there is a delay of 20 seconds until the next question. The more children respond during the delay, the more frustrated they are. Delay Reaction Time (DRT) - a stimulus appears 12 times on the center of a screen for 3 or 20 seconds, after which the screen turns blank. Children respond as quickly and accurately as possible to the disappearance of the stimulus, by pressing the mouse button. DRT = mean RT score for delay levels - RT on a simple RT condition with no delay. Psychopathology Page 11 TPD was measured with the following tasks: Tapping - an auditory tone is presented every 1200ms and the child needs to tap along at the same pace by pressing a response button (during 15 cued trials. Then, during 41 un-cued trials, there is no tone and the child needs to continue tapping at the previously cued rate. More variability of tapping on un-cued trials = bigger TPD. Duration Discrimination - children are presented with 2 brief tones and need to judge which one of them is longer. Time anticipation - children need to anticipate when a visual stimulus would reappear (it reappears after 400 or 2000ms). WM (with digit span), IQ and reading efficiency were also measured. Results 71% of the individuals displayed a neuropsychological deficit. Timing was the most common deficit and Inhibition was the least common. Overlap between the different deficits was uncommon and never greater than expected by chance. More than 70% of those affected showed just 1 deficit. Delay deficits were associated with IQ and literacy, whereas timing was significantly associated with literacy only. Siblings without ADHD had intermediate scores between the controls and the ADHD children. Siblings of ADHD children with Inhibition deficits were more impaired on Inhibition themselves than siblings of ADHD children without Inhibition deficits. The same was true for Timing deficits. Discussion This is the first evidence that Timing, Inhibition, and Delay deficits in ADHD are dissociable from each other and that substantial subgroups of patients are affected in only one domain. Siblings of probands with impairment in one of these domains also tended only to have problems in these domains, indicating that Inhibition and Timing deficits in ADHD breed true. Evidence was much weaker for the familial basis of the Delay components (consistent with previous literature). Timing was associated with reading problems. Delay problems were associated with low IQ and reading problems, although reading effects were mediated by IQ. Deficits in cognitive control, timing and reward sensitivity appear to be dissociable in ADHD - Zeeuw Article (2012) Introduction The study tests a 3-pathway model of ADHD, in which deficits in a dorsal frontostriatal pathway involved in cognitive control, a ventral frontostriatal pathway involved in reward processing and a frontocerebellar pathway related to temporal processing are implicated. Methods Subjects (ADHD and controls) participate in a 1.5 hour neuropsychological assessment, including IQ and tasks measuring reward sensitivity, cognitive control and timing. The difference between the approach of Sonuga-Barke is that the used tasks have been shown to be related to 3 distinct neurobiological systems (frontocerebellar pathway for timing, dorsal fronto-striatal pathway for cognitive control and ventral fronto-striatal pathway for reward processing). Neuropsychological battery Task 1 is a variation of the go/no-go paradigm that assesses cognitive control and timing. Task 2 assesses sensitivity to reward. Results The measures did not cluster together, but segregated into 4 components: cognitive control, timing, Psychopathology Page 12  The measures did not cluster together, but segregated into 4 components: cognitive control, timing, reward sensitivity and vigilance, each explaining 12.6%, 14.2%, 10.6% and 31.6% of the variance respectively. Discussion Deficits on the found components segregated between individuals with ADHD, providing support for a multiple pathway account of ADHD. The finding of a fourth component of vigilance deficits was not predicted by the model, but could relate to a fourth neurobiological system (possibly related to attention networks) involved in ADHD. Previous studies have suggested that both alerting and control components may be affected in ADHD. Overall the data was very similar to that of Sonuga-Barke, despite the different tests used and the different theoretical basis (psychological vs. neurobiological). Psychopathology Page 13