ABSTRACT
The aim of the present study was to determine the difference in executive functions among ADHD children and non-ADHD children. On the bases of literature review it was hypothesized that ADHD children have higher global executive composite as compared to non-ADHD children. It was further hypothesized that ADHD children have greater score on behavior regulation index than non ADHD children. It was hypothesized that ADHD children have greater score on Metacognitive index than non ADHD children. A sample of 30 children in which 15 children diagnosed as ADHD were selected from National Institute of Child Health(NICH) and Institute of Clinical Psychology and 15 children without ADHD with normal intelligence quotient was selected from differentschools y in Karachi. Their age range was from 6 to 12 years. Draw A Person (DAP) was used for IQ and Attention Deficit Hyperactive Disorder Test (ADHDT) was used toassess the range of ADHD symptoms in children. Behavior Rating Inventory For Executive Functions (BRIEF) was used to assess the executive functioning. It was found that there was significant difference between executive functions of ADHD and non ADHD children (t=, 4.464p <.05).Its was also found that there was significant difference between the Behavior Regulation Index (BRI) of ADHD and non ADHD children (t=6.720,p<.05).It was also found there was significant difference between the Metacognitive Index (MI) of ADHD and non ADHD children (t=3.239, p<.05).
INTRODUCTION
Attention Deficit Hyperactivity Disorder (ADHD) is a developmental disorder marked by significantly impairing symptoms of inattention, hyperactivity, and/or impulsivity, and symptoms must be present by the age of seven. Approximately 3-7% of school-age children have Attention-Deficit/Hyperactivity Disorder (ADHD). (American Psychiatric Association, 2000)Even as there is co morbidity between ADHD and specific learning difficulty. Some individuals find their learning problems appear to be due to the latter but clinical assessment and formal testing indicates that an attention deficit is the primary problem. (Young and Bramham, 2007).
The association between ADHD and specific learning difficulty can be explained in three ways (1) attention impairments hamper learning; (2) working memory difficulties can affect the ability to unravel complex grammar; and / or (3) both conditions share similar neurobiological underpinnings particularly those relating to executive dysfunction (Denkla, 1996).Attentional problems tend to be the primary complaint of ADHD client, who describe experiencing difficulty focusing on task and shifting the focus of their attention is necessary. There are four facets of attention that are commonly affected in ADHD (selective; divided; shifting; sustained). Attentional impairments may causemany problems in day-to-day functioning, including difficulty listening, failure to finish tasks and being easily distracted. An example of the types of attentional problems experienced by clients with ADHD their performance on the test of everyday attention was used by Young and Bramham (2007) in an experiment which indicated that people with ADHD have great difficulty multi-tasking. In order to complete a task well, and with out making errors, they have to apply all their resources to focus on that task. Difficulty with sustaining attention is probably the most pronounced and disabling attentional problem as individuals often struggle to engage in activities that are long, irrespective of whether they are repetitious or tedious. If a task is lengthy and also tedious, the client with ADHD is likely to completely leave the task. The chores that we have to do in our daily lives are by definition routine and many are boring and repetitious. It is not possible to have a daily routine that is consistently full of excitement and high stimulation. For ADHD individuals it’s very difficult to maintain a routine due to attentional problems. (Young Bramham, 2007).
Children experiencing ADHD have executive control deficits. Of particular importance to parents and teachers is the critical link between executive control and ADHD. Effective working memory is vital to concentration. Most individuals diagnosed with ADHD have a problem retaining information in working memory due to inattentiveness or impairment in blocking environmental interference. When working memory is impaired, newly learned information is not fully encoded, and is thus unavailable for retrieval later on. All of the executive control deficits indicated above have been observed in people diagnosed with ADHD. Rather, the manifestation of these syndromes is somewhat distinctive in each individual. Thus the basic rule in assessing these problems is to detect patterns of dysfunction. (Cox,2007) Gioia et al. (2000) defines that the executive functions are collection of processes that are responsible for guiding, directing, and managing cognitive, emotional and behavioral functions, particularly during active, novel problem solving. The term executive functions represent an umbrella construct that are responsible for purposeful, goal directed, problem solving behavior. Executive Functions is a term used by psychologists and related neuroscientists to describe a unique set of mental functions. Research has verified that these functions are performed by the prefrontal lobes of the cerebral cortex, in conjunction with sub cortical regions of the brain (limbic system). It is only within the last decade that executive functions have come to be fully appreciated for their impact on cognitive and emotional functioning, and more specifically, cognitive inhibition and initiation, self-regulation, and motor output. In general, executive functions are a collection of related, yet distinct abilities that provide for intentional, goal-directed, problem-solving action. Executive functions are conceptualized as metacognition in the sense that they coordinate numerous subdomains of thought and action.
The executive functions (EFs) have an important role in the developmental psychopathologies.Pennington, Bruce, Ozonoff and Sally (1996) demonstrate that EF deficits are found in autism and attention deficit hyperactivity disorder (ADHD) but not in conduct disorder or Tourette syndrome. While EF deficit profiles and severity vary across ADHD and autism, the molar EF deficits are more severe in autism than in ADHD. Studies of more specific EF tasks show defective motor inhibition in ADHD and verbal working memory in autism.
In numerous studies it is reported that children and adults with ADHD tend to perform more poorly than normal controls on the measures of executive function, some researchers began to describe ADHD as a disorder of executive function. In 1999 Castellanos noted that ADHD is “… not merely a deficit of attention, an excess of locomotor activity or their simple conjunction …”.He observed that “the unifying abstraction that best encompasses the faculties principally affected in ADHD has been termed executive function, which is an evolving concept … there is now impressive empirical support for its importance in ADHD”(Castellanos, 1999,cited in T.E. Brown (2006). Marc & Crundwell (2005) examined the relationship of regulation and emotionality on behavior problems in children with ADHD. Boys with ADHD who showed greater emotionality in terms of anger/frustration and less self-control and inhibition were rated as having more behavioral difficulties. Children with symptoms of hyperactivity and Impulsivity were rated as lower in self-control and inhibition and higher in emotionality.
Martel et al. (2007) conducted a research on executive functions among adolescents with ADHD. The ADHD group exhibited impaired performance compared with the non-ADHD group on executive function measures. There were no ADHD subtype differences. A composite executive function factor was significantly related to inattentive but not hyperactive-impulsive symptoms.
Mahone & Hoffman (2006) examined comparing parent ratings of 25 preschool children with ADHD to 25 age, sex, and SES-matched controls from the BRIEF-P standardization sample. Children with ADHD were rated significantly higher than controls on all five primary scales (Inhibit, Shift, Emotional Control, Working Memory, Plan/Organize), and on all four indices (Inhibitory Self Control, Flexibility, Emerging Metacognition, General Executive Composite). The largest effect size was on the Working Memory scale. All five BRIEF-P clinical scales were significantly intercorrelated in the control group, and seven of ten scale intercorrelations were significant in the ADHD group. Within the ADHD group, the BRIEF-P Index scores were significantly correlated with ratings on the Conners' Parent Rating Scale, but only moderately correlated with an estimate of Verbal IQ. The BRIEF-P had low, non-significant correlations with performance-based measures of EF, and patterns of correlations were not significantly different than those between the BRIEF-P and non-EF measures (sensorimotor, receptive vocabulary).
Marusiak & Janzen (2005) investigated the working memory abilities of children with attention deficit/hyperactivity disorder (ADHD) as measured by the Stanford-Binet Intelligence Scales, Fifth Edition (SBV). The ADHD children scored significantly lower in measures of working memory compared to the control group. Within the ADHD group, working memory was the lowest factor score, significantly lower than three of the four other factors. Significant differences were also revealed within the working memory factor, with ADHD children displaying significantly lower nonverbal working memory scores than verbal working memory. No such differences were evident in the control group.
Mullane & Corkum (2007) conducted a study on the Relationship between Working Memory, Inhibition, and Performance on the Wisconsin Card Sorting Test in Children With and Without ADHD, children with ADHD performed more poorly than children in the control group on a composite measure of working memory and a measure of behavioral inhibition.
Karatekin & Canan (2004) conducted a study on the integrity of specific aspects of the working memory system in attention-deficit/hyperactivity disorder (ADHD) within the framework of Baddeley's model by testing children with and without ADHD on verbal and spatial working memory tasks. Their study suggests that the children with ADHD were impaired primarily on the most difficult condition that required them to divide their attention between two tasks at the same time.
Mares, McLuckie, Schwartz and Saini, (2007) conducted a research to investigate the difference of Executive Function Impairments in children with ADHD in school and home environments. The primary purpose of their study was to compare parent and teacher reports of executive function (EF), as measured by the Behavior Rating Inventory of Executive Function (BRIEF), on a sample of children who had been diagnosed with attention-deficit hyperactivity disorder (ADHD). They compared parent and teacher ratings and applied logistical binary regressions to predict the probability of a child’s meeting the criteria for clinically significant inattention and hyperactivity–impulsivity on the ADHD Rating Scale-IV. Teachers reported more variety and severity of EF impairments than did parents. In addition, teachers used inhibition, organization of materials, and planning and organizing as predictors of ADHD symptoms, whereas parents relied predominantly on inhibition, working memory, and planning and organizing as the risk factors. Consistent with the current theory, EF impairments, particularly in inhibition, appear to underlie the behavioural manifestation of ADHD.
Bramham et al. (2009) conducted a studyto determine whether executive functioning deficits that characterize neuropsychological profiles of children having ADHD and autistic spectrum disorder ,similar impairments exist in adults with ADHD and ASD in comparison with a healthy control group, whetherthe two disorders can be distinguished on the basis of theirexecutive functioning features, and whether these impairmentsare related to symptom severity. Both clinical groups were foundto exhibit executive functioning deficits. The ADHD group haddifficulty withholding a response, with relative preservationof initiation and planning abilities. In contrast, the ASD groupexhibited significant impairments in initiation, planning andstrategy formation. The specific executive functioning deficitswere related to severity of response inhibition impairmentsin ADHD and stereotyped, repetitive behaviours in ASD.
Lawrence et al., ( 2004) investigated relationship of executive function and ADHD by comparing children’s performance during neuropsychological testing and real world activities . There were no group differences in executive functionon the Stroop or zoo tasks, but the ADHD group exhibited deficitsin set-shifting as assessed by the WCST (perseverative errorsand responses) and videogame play (fewer challenges completed).Also, the ADHD group showed slowed processing speed on the Stroop(slower color naming) and zoo activity (longer time to completetask), as well as a slower rate of acquisition of the sortingrule on the WCST (more trials to complete first category). Efficientand flexible videogame play (number of challenges completed)was related positively to efficacy on the Stroop (number ofitems named correctly in the interference and two control conditions)and inversely related to set-shifting problems on the WCST (perseverativeresponses and errors). Also, problems in goal-directed behaviorat the zoo (number of deviations from designated route) wererelated to problems in set-shifting on the WCST (perseverativeresponding).
Clark, Prior and Kinsella (2000) conducted a research to investigate whether executive deficits differentiate between adolescents with ADHD and Oppositional Defiant/conduct Disorder. Two neuropsychological measures of executive functions--Six Elements Tests (SET) and Hayling Sentence Completion Test (HSCT)--were administered to 110 adolescents, aged 12-15 years. Participants comprised four groups: Attention Deficit Hyperactivity Disorder (ADHD) only, ADHD and Oppositional Defiant Disorder/Conduct Disorder (ODD/CD), ODD/CD only, and a normal community control group. Results indicated that adolescents with ADHD performed significantly worse on both the SET and HSCT than those without ADHD, whether or not they also had ODD/CD.
Pasini et al., (2007) conducted a research to conform that Attention deficit hyperactivity disorder (ADHD) has been associated to executive functioning and sustained and divided attention deficits. In order to clarify the questions on neurocognitive impairment in ADHD, they investigated the presence of specific executive functions (EFs) and attention deficit patterns in ADHD clinical subtypes. Five main domains of EFs and attention were studied. Executive functions-related neurocognitive abilities were used as control tasks. ADHD patients, inattentive and combined subtypes differ from controls on response inhibition, divided attention, phonological, and visual object working memory and on variability of reaction times measured with CPT. Comparison of ADHD subtypes, in five main domains of EFs, did not show evidence of different executive functioning profiles. Response inhibition can predict performance on working memory tests but it cannot predict performance on divided attention/set shifting and on sustained attention. ADHD boys exhibit a selective impairment on executive functions and attention tasks.
Sergeant, Geurts and Oosterlaan (2002) conducted a selective review of researchs to investigate specificity of deficit of executive functioning for Attention-Deficit/Hyperactivity Disorder. The selective review of research in the executive functioning (EF) was given for attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), higher functioning autism (HFA) and Tourette syndrome. The review was restricted due to changes in the classification of the disorder in recent years and secondly the heterogeneity of EF was restricted to five key areas of concern, inhibition, set shifting, working memory, planning, and fluency. The review made it clear that there are strong differences between child psychopathological groups and controls on these EFs.
Attention and response inhibition are two aspects of a more overarching collection of symptoms manifested by patients with ADHD forming a dysexecutive syndrome. Executive dysfunction beyond the core cognitive deficits in ADHD has been identified with tasks assessing spontaneous verbal production and cognitive flexibility .In a study by Young, Morris, Toone and Tyson (2006) it was concluded that normal adults plan and think through the solution for the task before beginning ,whereas ADHD patients do their thinking during task. This performance style obviously has major implications for a group of patients who are liable to be distracted during their everyday ‘on-line’ planning. (Young and Bramham, 2007).
Several studies have investigated memory functioning in adults with ADHD, possibly because forgetfulness or ‘losing track’ of thoughts is one of the most commonly reported difficulties experienced in everyday living for the patient group. There have been consistent findings of difficulties with working memory as measured by tasks such as the Digit span and spatial span subtests of the Wechsler Memory Scale – 3rd edition (WMS-III) (Wechsler ,1997b). Kitty , Anderson, and Castiello(2002)conducted a study to investigate multiple aspects of executive functioning in children with attention deficit/hyperactivity disorder (ADHD). Those areas include attentional components, impulsiveness, planning, and problem solving. The rationale of the study was based on neurophysiological studies that suggest frontal lobe dysfunction in ADHD. As frontal lobe functioning is related to abilities in executive control, ADHD was hypothesised to be associated with deficits in various areas of executive functioning.One of the most prominent neuropsychological theories of attention-deficit/hyperactivity disorder (ADHD) suggests that its symptoms arise from a primary deficit in executive functions (EF), defined as neurocognitive processes that maintain an appropriate problem-solving set to attain a later goal. Willcutt et al., (2005) conducted a meta-analysis, to examine the validity of the EF theory, of 83 studies that administered EF measures to groups with ADHD and without ADHD. Groups with ADHD exhibited significant impairment on all EF tasks. Effect sizes for all measures fell in the medium range, but the strongest and most consistent effects were obtained on measures of response inhibition, vigilance, working memory, and planning. Weaknesses in EF were significant in both clinic-referred and community samples and were not explained by group differences in intelligence, academic achievement, or symptoms of other disorders. ADHD is associated with significant weaknesses in several key EF domains. However, moderate effect sizes and lack of universality of EF deficits among individuals with ADHD suggest that EF weaknesses are neither necessary nor sufficient to cause all cases of ADHD. Difficulties with EF appear to be one important component of the complex neuropsychology of ADHD.