CENTER ON BEHAVIORAL MEDICINE
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Instruments for Evaluating Attention Deficient and Hyperactivity DisorderTerry Porter
There is no actual testing for ADHD. The diagnose is done by clinical assessment. Neuropsychological tests are useful to evaluate specific deficits through historical facts, physical examinations and basic psychological testing but can only be helpful in the actual diagnose of ADHD not a definitive (O’Laughlin, Murphy, 2000). There are computerized performance tests (CPT) of attention and vigilance, but these may not be useful diagnose of ADHD as the tests suffer from low specificity and sensitivity. These CPTs are useful only as research tools. In addition, actometers, actigraphs, and other tools may be useful for research purposes (O’Laughlin, Murphy, 2000).
Along with the CPT’s, clinicians use rating scale tests to help with the diagnose of ADHD. The behavior rating scales offer a means of gathering information from people who have spent months or years with the individual. The rating scales provide a means to quantify the opinions of others and enable the clinician to compare these scores to norms collected on large groups of children. Although they are a favorable assessment for ADHD, the behavior rating scales are opinions and are subject to oversights, prejudices and limitations on reality and validity.
The rating scales offer a quick and easy format of standardized sets of behaviors to insure specific behaviors are being assessed, are not costly nor time consuming and do not effect social bias. The tests include children from different socioeconomic, racial and ethic populations.
Test of Variables of Attention (TOVA)
The Test of Variables of Attention (TOVA) is a highly effective test and accurate screening tool for diagnosing ADHD along with behavior rating (TOVA, 2004). This test is useful in identifying attention deficits in children and adults as well as predicting and quantifying response to medication (Ferguson, 2004). The test features year-by-year norm based ages 4-80+ and differentiates attention from learning disabilities. It has test and retests reliability along with a vigilance and disinhibition subtest, which takes eleven minutes per test (Ferguson, 2004). This test will measure the inattention, impulsitivity and disinhibition response time and generate computer interpretation immediately (T.O.V.A., 2004).
The TOVA test has classroom intervention strategies based on results, which can be individualized and edited to include clinical observations. The test is useful in identifying ADHD in children and adults along with predicting and quantifying response to medication (Ferguson, 2004). The TOVA reduces the likelihood of under or over medication. It ensures that the medication dose is right for the child. It is also an excellent objective method of assessing the effectiveness of medication for ADHD without relying solely on parents’ and teachers’ reports. TOVA has an advantage and differentiates ADHD from learning and emotional/behavioral disorders. It helps the parent to understand the physiological basis of ADHD and the need for treatment (Behavioral Neurology Clinic, 2001).
The TOVA can be used by clinicians for measuring visual and auditory information, processing of neurological injuries and disorders, along with being a diagnostic tool as part of a mult-faceted, multidisciplinary assessment for individuals with ADHD.
The guidelines for many computer performance tests caution that individuals with above average IQ’s are likely to perform well despite attention and impulsive problems in other settings. Individuals with below average cognitive ability may have difficulty comprehending task directions, resulting in abnormal performance that may be primarily due to cognitive deficits (Behavioral Neurology Clinic, 2001).
Clinics offer this test as a service to pediatricians as an empirical means of prescribing ADHD medication (Ferguson, 2004). Parents may ask his/her pediatrician to test his/her child before medication is given and/or to adjust the medication dose. The clinic can provide this service without a pediatrician’s input. The TOVA reduces the risk of over and under medication along with a computer-generated report provided to the medical doctor (T.O.V.A., 2004).
Gordon Diagnostic System
The Gordon Diagnostic System (GDS) is an assessment device that aids in the diagnosis of ADD and ADHD, which provides reliable information about the individual’s ability to sustain attention and exert self-control. This device enhances the accuracy and relevance of a comprehensive evaluation for attention deficits and impulsiveness (Gordon Diagnostic System, 2004).
GDS provides the clinician with objective data based upon the child’s actual behavior and allows observation in a paradigm, which will likely elicit inattention and impulsiveness (Gordon Diagnostic System, 2004). For the adult the GDS data allows for standardized assessment of a critical area of functioning, which is often overlooked, in formal evaluation. This test can only be interpretative by a qualified professional. The GDS is used in evaluation of ADHD along with assessment of vigilance of behavioral inhibition (Gordon Diagnostic System, 2004).
Neurologists use GDS and neurophysiologists in evaluation for Tourettes Syndrome and to screen for inattention that may be follow the administration of anticonvulsive medication. The test is also used to test adults with closed head injury, liver damage or HIV infections (Gordon Diagnostic System, 2004).
On of the first commercial CPT’s to become widely used establishing a significant of published research studies and a long history of clinical settings. The GDS provides the clinician with objective data based upon the child’s actual behavior and allows for observation in a paradigm likely to elicit attention and impulsiveness. In addition, with adults, the GDS data allows for standardized assessment of a critical area of functioning, which is often overlooked, in formal evaluation (Gordon Diagnostic System, 2004).
Neurologists and neurophysiologists for evaluation of Tourette’s syndrome and to screen for inattention that may follow administration of anticonvulsive medication can use the GDS. It also can test for closed head injury, liver damage, or HIV infection (Gordon Diagnostic System, 2004).
At this time, there is no auditory version of the GDS. The test includes only visual stimuli and does not include the auditory component. The validity of this test is questionable. The task does not have any resemblance to anything the child will ever do in his/her life. The GDS creates an objective score that can be used as an important measure of a child’s ability to attend. Under some debate by the professional field of ADHD, the use of this kind of test is questionable (Armstrong, 1996),
The cost of the GDS is higher than most and includes limited use and scoring (O’Laughlin, Murphy, 2000).
The Gordon was one of the first CPT to be used so it is one of the most common clinical tests used in testing for ADHD. The test has been studied and researched more than any other so it has an acceptable test-retest reliability and longer history of use in a clinical setting.
Conners Continuous Performance Test
Conners Continuous Performance Test (CCPT) is a vigilance task in which respondents are asked to press a button when any letter but “X” appears on the screen (Conners, 2003). The major variables include number correct, omission errors and various reaction times. Test results can be obtained in six different tasks that provide interpretive guidelines, reaction times as well as raw scores, and t-scored percentiles for all of the major variables (Conners, 2003). The CCPT was based on a sample of 1200 children and adults ranging in ages from 4 to 70 years old (Conners, 2003).
Conners differ from other CPT assessment tests. The CCPT requires continuous responding with inhibition when presented with a target, whereas others involve responding to a target alone within a set of distracters. CCPT requires the subject to interrupt a continuous motor response; it is similar to the stop-signal tasks used to test disinhibition.
Conners’ Teacher Rating scale is one of the most popular rating scales used by the professionals. It has been used for over thirty years and has remained appealing and stable in its performance.
One strength of the Conners’ CPT is its cognitive measurement. Conners’ CPT differs from others in several respects. It requires continuous responding with inhibition when presented with a target, whereas others involve responding to a target alone within a set of distracters. The test requires the subject to interrupt a continuous motor response, it is similar to stop signal task that are used to test inhibitions. The testing process goes along with recent theory about the central deficits in ADHD.
The Conners’ CPT is one of the most popular tests administered by clinicians. It has been one of the leading choice of experts and is ideal for measuring treatment changes and outcome assessment purposes (Conners, 2003).
The brief 10 item on the Conners’ CPT parent and teacher scale was at one time the most frequently used instrument for selecting hyperactive children for research. Recent studies have suggested that the scale assesses a mixture of hyperactive and conduct problems and will select a mixed group of hyperactive/conduct-disordered children not ADHD alone (National Health and Mental Research Council, 2004)
This test is not ideal as a diagnostic screen because it misses children with attention deficit without hyperactivity. This test also suffers from low specificity and sensitivity as the others do. It is mainly a resource tool and not a diagnostic test. The test is not consistently sensitive to stimulant effects.
The overall index was not associated with internalizing or externalizing behavior problems, suggesting no confounding with anxiety or conduct problems. With boys committing more omission errors, no sex differences were detected. This appears to threat the test validity.
The Conners’ CPT demonstrated weakness in clinical study samples. It was found to show no univariate or multivariate association between the overall index of the Conners’ CPT and any parent or teacher rating of inattention or hyperactivity.
Weak or absent correlations between laboratory and behavioral measures of inattention and hyperactivity have been documented in other studies. These null results may reflect the restriction of range inherent in parent and teacher ratings in referred populations, which were virtually all clinically, referred children regardless of ultimate diagnoses. These results would be rated highly on such measures by parents and teachers. This suggests that Conners’ CPT is sensitive to teacher behavior ratings only at the highest levels of behavioral disturbance. The test appears to lack specificity to ADHD related to other clinical conditions.
Weakness of Conners’ CPT was the association with phonological awareness. As the phonological awareness skills decreased, Conners’ CPT overall index scores increased (Journal of Abnormal Child Psychology, 2000). Children with reading disorders would do poorly on the test. This would result to a significantly higher risk that children with reading disorders would be falsely diagnosed with ADHD when using the Conner’s CPT (Journal of Abnormal Child Psychology, 2000).
Conner’s CPT presents brief summaries of several published research articles as support for the validity of the CCPT but specific information regarding reliability is not reported (O’Laughlin, Murphy, 2000).
The Conners’ CPT demonstrates a number of significant strengths and weaknesses. It was not correlated with age, suggesting appropriate age norms. It also was not influenced with order or fatigue effects. The test was uninfluenced by visual-motor integration or fine motor speed, so peripheral motor competence has no bearing on the Conners’ CPT performance (Journal of Abnormal Child Psychology, 2000). The test was uninfluenced by visual processing speed with the exception of reaction time.
There has been an updated Conners CPT test available to the public in 2000. The CPT-II includes a larger normative sample, newly designed reports and more comprehensive software and inclusion of a validity scale (O’Laughlin, Murphy, 2000).
Attention Deficit Disorder Evaluation Scales
Attention Deficit Disorder Evaluation Scales (A.D.D.E.S.) was designed to provide a measure of each of the characteristics of ADHD. ADDES provides a means for referral information that can be objectively obtained by observers such as parents and classroom teachers. These individuals are in the best possible position to document a child’s behavior in order to be given a diagnosis of ADHD along with the characteristic behaviors that must be present in at least two settings, home and school.
The process age and gender related norms have been developed so individual results can be compared (Behavioral Neurotherapy Clinic, 2001)
As with any rating scale the ADDES is gender bias and can be opinionated.
The ADDES has been used for some years but seems to be not as popular as the other Behavior Rating Scales that have been used.
Gordon Diagnostic System
Gordon Diagnostic System (GDS) was the first commercial CPT to become widely available and used. The GDS is a self-contained portable unit, which administers two attention tasks and a test of inhibition control. The test contains separate adult, child and preschool versions of each of the three tasks (Gordon Diagnostic System, 2004). Parallel forms of each task are to reduce practice effects when retesting. The non-distracting version of the vigilance task, the client is asked to press a button when a certain combination of numbers flash on the screen. In the distracting version targets, digits are shown surrounded by distracting numbers. A third delay task requires the client to responding to earn points (Gordon Diagnostic System, 2004).
The acceptance of test reliability and validity for the GDS has been established through a significant amount of published research studies along with a history of use in clinical settings (National Health and Mental Research Council, 2004)
The test is user-friendly for the child taking the test. Test results can be obtained in six different forms that will provide guidelines, reaction times and major variables that can be compared to the general population norms for interpreting the results. The test is most effective for individuals 6 to 17 years of age (Gordon Diagnostic System, 2004).
It may be difficult to distinguish which part of the variance between teachers and parents are explained by a child’s behavioral pattern and which, by the individual response, can be biasness of the teachers and parents themselves. Situational specificity may account, in part, for epidemiological differences between research studies done outside of the United States. This explains why the DSM-IV and ICD-10 requires that diagnosis be made in multiple settings (National Health and Mental Research Council, 2004).
The Gordon Diagnostic System (GDS) seems to be not as widely use as the Conners’ CPT or TOVA but is considered useful in clinical assessment of a child with ADHD. Clinicians using the GDS find the assessment to be important tool in doing a comprehensive diagnostic evaluation of children with ADHD (Gordon Diagnostic System, 2004).
Achenbach Child Behavioral Checklist
Achenbach was one of the most carefully developed and standardized methods, for addressing a broad array of psychopathological manifestations in children and has been widely used in epidemiological studies (National Health and Mental Research Council, 2004).
The Achenbach Child Behavioral Checklist or Child Behavioral Checklist (CBCL) is a behavioral rating instrument designed to be completed by parents and/or parent surrogates of children aged 4 to 18 years old (ADHD Screening, 2004). The 113 item rating scale requires parents to rate his/her child’s behavior on a Likert-type scale using the descriptors “not true”, “sometimes true”, “very true”, and “often true” about his/her child. The results of the rating scale assist in determining the presence of externalizing or internalizing behavioral problems (ADHD Screening, 2004).
The assessment of ADHD can also externalize disorders such as conduct, aggressiveness, and hyperactivity. Comparisons of parents’ perceptions can be made when both parents are available to complete the rating on a child so less bias. The teacher will also use a rating scale to be completed on the child. This is one of the most popular rating scales of its type about the child in the classroom (ADHD Screening, 2004).
This form of testing has relatively low agreement between the parents and teachers. The scale is designed for professional and/or semi-professional use and that some items may make it difficult for the parent to use (National Health and Mental Research Council, 2004).
The use of the Achenbach rating scale is only part of an assessment used in the diagnosis of a child/adult who has ADHD. The scores are used to rate if the individual has externalizing behaviors that may result in ADHD, conduct disorder or other emotional behaviors (ADHD Screening, 2004).
Barkley’s Current Symptoms Scale-Self Report Form
Barkley’s Current Symptoms Scale-Self Report Form is a scale of 18 items that address the symptoms listed in the DSM-IV diagnostic criteria (Functional Behavioral Assessment, 2004). Odd-numbered items assess frequency of inattentive symptoms and even-numbered items assess hyperactive/impulsive symptoms on a 0 to 3 Likert-type frequency scale (Functional Behavioral Assessment, 2004). The scale also asks the adult at what age the onset of ADHD symptoms and to tell how often the symptoms interfered with activities such as school, relationships, work and the home. The assessment also addresses Oppositional Defiant Disorder (ODD) co morbidity with eight questions about symptoms of ODD (Functional Behavioral Assessment, 2004).
Barkley has a Child Symptoms Scale-Self Report Form in which the parent can complete. The scale forms a picture of the child/adults past and present symptoms and functioning (Functional Behavioral Assessment, 2004).
The advantage to the Barkley rating scale is the teacher/parent version is developed for rigorous standardization and specific norms (ADHD screening, 2004).
The scale is used to determine if the child/adult displays ADHD symptoms and is only part of a series of diagnostic tools. The rating scale can be subjective and biased by the parent or teacher when rating the performance of the child (National Mental Health Research Council, 2004).
The test does not employ the precise symptom lists for inattention and hyperactivity along with high scores not being an appropriate diagnose for ADHD.
The Barkley behavior rating scale has its advantages and disadvantages. The clinician must choose which rating scale would best suit the needs of the child/adult being diagnosed with ADHD, and which scale would benefit in assessing the individual most accurately.
About Computerized Performance Tests, CPTs
From researching the use of CPT’s for diagnosis of ADHD, there are some cautions that need to be addressed. The primary criticism of the use of the CPT’s involves the validity, high rate of false negatives, and the limited ability of CPT’s to discriminate between ADHD and other clinical disorders. Some feel the examiner presence may result in a better performance for children who respond better one to one. The use of computer-based task scales may result in performance that is an overestimation of typical ability to maintain attention due to the novelty and attractiveness to the child. Although it may be attractive to the child, the child may not be familiar with the mouse and displays performance anxiety by the clinical condition, causing a greater deficits than would be in a natural environment. The clinician needs to address the ecological validity gathering different behaviors of the child in different situations. The child who performs well on an individually administered computer test of attention may display different behavior in other settings (O’Laughlin, Murphy, 2000).
Due to false negative rates being higher, researchers have caution that “normal” CPT performance should not be used as evidence to rule out a diagnosis of ADHD. In addition, individuals with above average IQ are likely to perform well despite attention and impulsivity problems in other settings. Those with below average cognitive ability may have difficulty comprehending the task directions resulting in abnormal performance that is primarily due to cognitive deficits (O’Laughlin, Murphy, 2000).
The ability of the CPT’s to distinguish between ADHD and other clinical disorders is a major concern for most practitioners since psychotherapy interventions may vary depending on the true diagnosis. Different studies have found that CPT’s have been inconsistent in differentiating ADHD from other clinical groups. CPT data and observations made during the CPT may assist the clinician to differentiate between conduct problems and ADHD, and to provide information about intentionality of impulsive response (O’Laughlin, Murphy, 2000).
CPT’s do help to monitor medication effectively and allow for the use of correct dosage and effective medication for the individual.
In conclusion, what ever the choice is for the clinician be it a CPT assessment or Behavior Rating Scale to be used as one of the tools for diagnosing ADHD, the test should be practical and easily interpreted. The cost, along with time consumption or complicated assessment would not benefit the clinician on his/her assessment of the child. Besides these factors, the child may become frustrated in the assessment setting. The clinician needs to be practical with the psychological testing and observational techniques.
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