Assessing children and adults for Attention Deficit Hyperactivity Disorder (ADHD) can offer crucial insight into one’s functioning and, thereby, guide life-impacting treatment decisions. These include providing input into educational interventions, determining eligibility for disability requirements, and evaluating therapeutic or scholastic outcomes.

Finding and utilizing reliable assessment tools – along with therapeutic supports to efficiently address ADHD – is key. This process begins with understanding the  multitude of factors that can impact an ADHD diagnosis:

  • high prevalence rates (more on this below)
  • concerns about over-diagnosis
  • the adverse influence ADHD can have on functioning at home, school, work, and in social relationships
  • the fact that ADHD often coincides with another disorder.

These factors collectively provide an impetus for developing and implementing measures that can accurately diagnose this condition from the onset. This article reviews widely recommended professional guidelines in the scientific literature – that is, best practices – to assess ADHD and the limitations often faced with evaluating ADHD.

Prevalence and Costs Associated with ADHD

ADHD is the most common behavioral condition seen in children and adolescents in the United States, affecting 10% of those ages 4 to 17 years old. Compare this to 7% seen in 1998 to 2000 and a worldwide prevalence rate of 5%, the latter explained by different diagnostic instruments and guidelines and access to healthcare.1

It is notable that incidence rates increase with age. Estimates of ADHD among those 10 to 17 years old are almost twice as high as those for children 5 to 9 years old.1

In 2013, US healthcare expenditures for ADHD totaled $23 billion.2 Societal costs – such as healthcare, education, and reduced family productivity associated with childhood ADHD – have been estimated to range from $38 billion to $72 billion per year.3

Long-term studies show that “children and adolescents with ADHD are more likely to experience a variety of negative outcomes compared to their peers without the disorder, including lower academic attainment, impaired social functioning, increased risk of hospital admissions and injuries, increased substance use and risk of a substance use disorder, and reduced income and participation in labor markets as adults.”4-8

Classifying an ADHD Diagnosis: Current Understandings, Overlapping Disorders

ADHD is now more accurately viewed as a neurodevelopmental disorder. This conceptualization has been widely supported by more than two decades of research noting how the condition often, but not always, is diagnosed in childhood and is intricately connected to brain-behavior relationships involving executive functioning (eg, attention, impulse control, self-regulation, organization/planning, and working memory) that presents differently across the lifespan. The American Psychological Association recognized and codified these distinctions in the DSM-5.

This shift in appreciating the connection between executive functioning and ADHD over the past 20-plus years has translated to the development of neuropsychological batteries to evaluate the disorder. In addition, current understandings have influenced targeted areas measured in continuous performance tests and led to appreciable revisions of rating scales. (See Table I below on the various assessment tools available.)

A challenge with diagnosing ADHD is that the characteristics associated with the disorder – such as difficulties with focusing, shifting/dividing attention, managing frustration, organization/poor time-management, working memory, and staying engaged – are common symptoms that could have a breadth of etiologies.

As noted, more often than not, ADHD coincides with another disorder. As per a national 2016 parent survey, 6 in 10 children with ADHD had at least one other mental, emotional, or behavioral disorder.9 The most common co-occurring conditions reported with ADHD include: 9

  • 52% behavioral or conduct problems
  • 33% anxiety disorders
  • 17% depression
  • 14% autism spectrum disorder
  • 1% Tourette syndrome

A small percentage (1.0%) of adolescents aged 12 to 17 years with ADHD also had a parent-reported current substance use disorder (SUD).

ADHD Assessment: Current Evaluation Tools and Their Limitations

Clinicians Involved in ADHD Diagnosis

Assessment of ADHD is conducted within a wide range of professions, that include, but are not limited to:

  • clinical psychologists
  • school psychologists
  • neuropsychologists
  • psychiatrists
  • neurologists
  • pediatricians/neurodevelopmental pediatricians
  • internists/family physicians.

Evidence-Based ADHD Assessment: False Positives and False Negatives

Regardless of the healthcare expert charged with diagnosing/evaluating potential ADHD, a well-regarded and arguably gold standard approach is using an evidenced-based assessment that involves adherence to the DSM-5 diagnostic criteria along with the inclusion of multi-informant/multimethod methods. Such methods should incorporate empirically validated research and, when possible, test data about key clinical populations to guide and increase confidence with clinical impressions.

With all assessment measures, an overriding goal is to improve the sensitivity and specificity of the instrument. Sensitivity is the ability of a test, such as a rating scale, to correctly identify those with the condition, whereas specificity is the ability of a test to correctly identify people without the condition. These statistics are of particular concern with ADHD given its impact across the lifespan.

Erroneous diagnostic impressions have real-world consequences. A false negative could impede necessary treatment efforts (eg, academic/occupational accommodations, medication, counseling) for one who is struggling at home, school, or work. False-positive errors can lead to inappropriate provisions of medication, academic accommodations, diminish educational resources, as well as provide an unfair advantage to those without disabilities.10,11

Table I: A Quick Look at Available ADHD Assessment Tools.

Rating Scales

Neuropsychological Measures/Batteries

The Clinical Interview

Narrow Band (ADHD symptom-specific):

  • Barkley Adult ADHD Rating Scale-IV (BAARS-IV)
  • Brown Attention/Executive Function Scales
  • Behavior Rating Inventory of Executive Function 2 (BRIEF-2)
  • Conners Adult ADHD Rating Scales (Conners-3, CAARS*)
  • Comprehensive Executive Function Inventory (CEFI)

Broadband (behavioral conditions in addition to core ADHD symptoms):

  • Behavior Assessment System for Children (BASC-3)
  • Child Behavior Checklist (CBCL)
  • Connors Comprehensive Behavior Scale (CBRS)

These information-gathering tests can provide information related to brain function and help to identify weaknesses associated with ADHD in specific areas (eg, working memory, impulsivity, poor concentration) as well as the potential real-world consequences of them (eg, reading comprehension difficulties). The results can inform treatment recommendations (eg, medication, academic accommodations, counseling).

Examples include:

  • Delis-Kaplan Executive Function System (D-KEFS) (Ages 8 through adulthood, up to 90 minutes)
  • Subtests from the NEPSY-2 especially the subtests from the Attention/Executive Functioning domains, which include Animal Sorting, Auditory Attention/Response Set, Clocks, Design Fluency, Inhibition; Inhibition, and Statue
  • Neuropsychological Assessment Battery (NAB) Attention module (Ages 3 to 16, 45 to 90 minutes)
  • Rey Osterrieth Complex Figure ( ROCF) (Ages 6 through adulthood, 45 minutes with a 30-minute interval)
  • Wisconsin Card Sort Test (WCST) (Ages 6.5 through adulthood 20 to 30 minutes)
  • Wechsler Intelligence Scale for Children- Fifth Edition Working Memory Scale: Digit Span, Picture Span, Letter-Number Sequencing
  • Continuous performance tests
    • Conners’ Continuous Performance Test 3rd Edition (Connors CPT-3)
    • Test of Variables of Attention-9 (TOVA-9)
    • Evaluate Visual and Auditory Attention (IVA-2)
    • Qb Test
Used to solicit information about – and observe – executive functioning deficits; to be done in combination with one or more measures/tests above and patient’s history for a full assessment.


ADHD Presentations, Measures, and Assessment Tool Accuracy

While knowing whether an assessment tool (eg, a rating scale, continuous performance test, or neuropsychological testing battery) can correctly discriminate between those who have a disorder from those who do not is a fundamental objective of its design, it is equally important to know the probability of that test’s diagnostic formulation being correct. Such information can be attained if the base rate of a condition is known.

Marshal et al discussed that assessment tools increase their diagnostic accuracy when incorporating positive predictive power (PPP) and negative predictive power (NPP).12 Having data regarding the prevalence of ADHD within a particular population across settings –whether in school, clinic, or at home – enhances the utility of the measure being used.

There is a growing focus on improving healthcare diagnostic skills through the application of probabilistic reasoning to the interpretation of diagnostic tests, using classification statistics, which allow clinicians to make highly informative and scientifically responsible statements regarding the probability of a particular diagnosis given the test finding.13 In essence, these statistics use the knowledge of the base rate within a population to determine the probability of whether a person identified by a measure is showing signs of a condition, actually has the condition (PPP), or when they do not meet criteria for a disorder – the likelihood (NPP) that they do not have it.

Notably, Gioia et al recently asserted that leveraging classification statistics (involving base rates) in their rating scale (BRIEF-2 ADHD Form) increases the efficiency of this instrument by not only distinguishing those with characteristics of ADHD from other psychiatric conditions but also by helping to delineate the different ADHD presentations (ie, impulsive/hyperactive [ADHD-HI], predominantly inattentive/distractible [ADHD-I], and combined [ADHD-C]).14

Gioia et al further noted that multiple studies using the BRIEF and BRIEF-2 have found distinctive profiles for ADHD within a clinical population. Those with ADHD-I had elevations in working memory, planning/organizing, and initiation. A similar pattern emerges with those with ADHD-C, yet they also had an elevation on a scale that measures inhibitory control.

The DSM-5 uses a dimensional approach with diagnoses. In the current manual, ADHD is viewed as a constellation of attentional and hyperactive-impulsive symptoms that must occur “often” and “interfere with, or reduce the quality of, social, academic, or occupational functioning.”15 This leaves room for the healthcare professional to use their clinical acumen to determine whether an individual presentation seems to fit this referenced diagnostic conceptualization.

It is widely known that while interviewing is the most commonly employed approach to ascertain an ADHD diagnosis, it is quite flawed and additional steps are required for diagnostic accuracy. In short, clinical interviews are troubled by issues with validity due to an individual’s poor recall of childhood experiences, lack of insight about ADHD symptoms, and/or the possibility of positive illusory bias.16

(See also, Psycom Pro’s series on the external factors that may influence an ADHD diagnosis).

There are considerable questions involving diagnostic formulation when left to simply rely on information gleaned from personal accounts, outside observers, and/or medical/educational records to depict an individual’s functioning. Marshall et al contend that assessing ADHD on professional judgment “is not enough and the implementation of behavioral rating scales are warranted since they are more precise in quantifying symptom experiences and are therefore potentially more helpful than a clinical interview in clarifying whether the patient experiences ADHD symptoms that meet these two specific criteria.”12

Validity Versus Sensitivity and Specificity

Rating scales often accompany clinical interviews as methods to assess ADHD. There are several broadband and narrowband rating scales that are widely used and well regarded (*see Table I on available assessment tools). The advantages of many of the aforesaid standardized questionnaires include standardization in how they are administered. For instance, multiple sources of feedback are solicited (ie, parent, self, teacher, observer) across a variety of settings (eg, home, school, work) and they can be administered to individuals across the lifespan in person or remotely online (which has been particularly useful during the COVID-19 pandemic). In addition, the completion time for the narrowband measures are reasonable (10 to 20 minute) and validity measures are embedded.

Even with these favorable assets in rating scales, however, there are limitations that hinder this type of assessment tool. Issues involving sensitivity to detect ADHD and specificity to rule out ADHD are arguably a work in progress with all rating scales, particularly with those whose studied comparison groups were typically developing individuals or members of the general population. Marshall et al commented on this shortcoming regarding those in college (although this is applicable to a pediatric population as well), stating that such stu­dents are generally more intelligent and higher functioning in many respects than the general population.12 Consequently, students with ADHD may have scores in the aver­age range on ADHD-related measures while their scores would fall in the impaired range relative to those in college.17

Thus, there continue to be challenges with rating scales involving the accuracy of arriving at ADHD presentations when information is obtained through multiple sources (self, parent, teacher, significant other). As noted, Gioia et al address this in their BRIEF-2 ADHD Form using base rates to enhance the predictive power of impressions by not only identifying those with characteristics of ADHD from other psychiatric conditions but also by using it to delineate the different ADHD presentations.14

The ADHD Clinical Interview

As noted, of the methods used to diagnose ADHD, the clinical interview is the most common approach but it is fraught with concerns given considerable deficiencies involving validity and reliability. Neuropsychological testing employed to help diagnose ADHD does improve upon the weaknesses of a clinical interview in both internal and external validity. Where clinical interviews often fall short, neuropsychological measures provide standardization of the administration of the instruments.

In recent years, there has been an emphasis on ensuring that a normative sample is reflective of the testing population across the lifespan (often based on age, gender, ethnicity, and education) with both typically developing individuals and those within a clinical population. This push facilitates greater confidence in generalizing findings. In other words, whereas a clinical interview assessing ADHD solicits information about executive functioning deficits, neuropsychological testing or performance-based measures affords the evaluator with an opportunity to observe it in action.

Neuropsychological Testing and Performance-Based Measures for ADHD

Impressions from neuropsychological testing can yield fruitful insight for an individual, caregivers, a school, or an employer by identifying weaknesses associated with ADHD in specific areas, the likely real-world consequences of them, and accompanying treatment recommendations based on these challenges. However, research on the diagnostic utility of neuropsychological testing as the sole method to determine ADHD is mixed at best.

There has been considerable discussion as to the clinical utility of neuropsychological evaluation for the diagnosis of ADHD. Sensitivity, specificity, and positive and negative predictive power of specific neuropsychological tests have been insufficient to propose using them as a sole determinant of ADHD diagnosis.1

Notably, neuropsychological testing in clinical practice is conducted without the inclusion of additional sources of information, including rating scales, a clinical interview, and/or a records review. Several studies have examined whether those with ADHD test differently across various facets involving intellect, memory/working memory, attention/concentration, impulse control, mental and motor processing speed and executive functioning. In fact, “the vast majority of individual cognitive tests clearly indicate that many adults with ADHD perform in the normal range and only a minority of them will ren­der an impaired performance on any specific test” according to Nigg et al.18

Further, Barkley has contended neuropsychological assessment may have limited ability to discriminate between adult ADHD and other psychiatric disorders in a psychiatric assessment.19 Yet, one pattern that emerges is that individuals with “ADHD are consistently inconsistent in their performance on neuropsychological tests over time”20 “as they can often rally to focus their attention for brief periods of time on any one test measure”21

By and large, the compositions of neuropsychological batteries differ between practitioners but will frequently include a measure that examines sustained attention and inhibitory response. Often, this measure is a continuous performance test, such as the widely used Conners CPT3 or TOVA-9, which are administered through a computer-based program and entail the rapid presentation of a series of visual or auditory stimuli (eg, numbers, letters, number/letter sequences or geometric figures) over a set timeframe.

Quantitative data on different variables of interest involving omission, commission, and reaction time are associated with inattention, impulsivity, and sustained attention. Among neuropsychological measures, continuous performance tests have been shown to be useful in augmenting the detection of ADHD but are poor ruling out other conditions.22-27

Further, a common criticism of continuous performance tests is that their ecological validity is low. They are unable to simulate the difficulties of patients in everyday life given that they are conducted in controlled settings that remove environmental distractions.28,29

Invalid Symptom Presentations of ADHD

Making testing more complicated is that, as stated throughout the literature, some “individuals may be motivated to feign or exaggerate ADHD symptoms in order to gain medication or accommodations on high-stakes examinations or to enhance their performance in school or at work.1 The percentage of young adults who exhibited invalid symptom presentations during a comprehensive ADHD assessment were considerably elevated from 31% to 53%.30,31

Among college students, the base rate of those malingering seeking medication for ADHD was 10%  in a study by Weiss et al.32 Hirsch and Christiansen found that within a significantly older adult population, 32% conveyed an invalid presentation.33

While the data on examining feigning illness in children is an arguably recent body of research that is growing, there is evidence that some children and adolescents do engage in deceptive practices during assessments for secondary gain. In their work on developing the Pediatric Performance Validity Suite (PdPVT), a measure designed to assess the credibility of performance in children/adolescents, McCaffrey, Lynch, Leark, and Reynolds cite a variety of factors why some children and adolescents may malinger.34 Some reasons may relate to seeking a disability diagnosis in order that caregivers may receive disability benefits, to access special services or accommodations at school, or to qualify for various testing programs. In essence, the research has shown that it is rather easy to “fake” symptoms or present oneself in a way that is incongruent with how one is actually functioning.

The economic costs of those who engage in dissimulation are extraordinary. Even with the gains made in possessing representative samples requisite for generalizing findings derived from rating scales, neuropsychological batteries, and tests administered as part of the evaluation to assess ADHD, the accuracy of the diagnostic impressions are a function of whether the person performed or answered faithfully.

Questions as to whether one is being disingenuous during an evaluation have been a focus of research and clinical practice for more than 40 years. Research suggests that the accuracy of an ADHD diagnosis is contingent upon the employment of validity scales and whether they are delivered in freestanding instruments solely examining dissimulation or in integrated component/scales that examine a range of areas, such as sustained attention and socio-emotional/behavioral functioning. Clinicians have attempted to address the possibility of invalid presentations by implementing symptom validity, performance validity, or effort testing in the form of standalone instruments solely focused on this area (ie, deception). Some validation tools have been directly embedded in measures that attempt to elicit these response styles (eg, scales capturing faking good/bad or infrequency).

Discussion of ADHD Assessments: Which Tool is Best for Diagnosis?

In short, there is no one-size-fits-all diagnostic tool to assess ADHD. Myriad factors come into play including:

  • the psychometric properties of evaluation methods, including validity, sensitivity versus specificity, and positive and negative predictive power
  • the heterogeneity of neuropsychological test batteries based upon the evaluator’s training, familiarity with instruments, financial means, and challenges of complete objectivity
  • concerns about patients/clients feigning illness/symptoms

Kirk and Boada posit that the:

 “complexity in this diagnostic process arises because clinically significant symptoms of inattention, hyperactivity, and impulsivity are not confined to ADHD. They occur in many other developmental psychiatric and neurological conditions. Additionally, children with ADHD often have comorbid learning and psychiatric disorders that require appropriate evaluation in their own right, so that a comprehensive treatment plan can be devised.”1

Given these factors, this writer supports the recommendation by Gioia et al that an evidenced-based assessment be carried out to make an accurate ADHD diagnosis.14 This means using one’s clinical expertise to integrate the best available research within the context of an individual patient’s history, observations, and test data to guide clinical decision-making.

In doing so, more accurate clinical decisions are likely, ultimately improving patient outcomes. With this in mind, the following are considered best practices and recommended by Weiss et al to validate an ADHD diagnosis:32

  • Use norm-referenced scales to determine the presence of significant symptoms that are incongruent with developmental expectations. Author’s Note: these should include validity measures that assess for deception.
  • Use supplementary sources of information such as academic or medical records or even accounts of developmental history shared by caregivers than relying on self-report recall of childhood symptomology as the latter is not viewed as a reliable method.
  • Assess across settings (eg, school, home, work)
  • Examine the level of impairment with everyday functioning. It is arguably more important and reliable to consider functional impairment than solely assessing symptom count or severity. It is well known that some individuals with marked severity in symptoms have learned compensatory strategies to function effectively, whereas others who may not meet all symptom criteria on the DSM-V ADHD diagnosis, but have pronounced difficulties meeting expected daily demands.
  • Rule out alternative explanations that may account for symptoms associated with ADHD such as physical ailments (eg, endocrine disorders, hypoglycemia, hearing impairment, traumatic brain injury), reactions to medications/treatments (eg, chemotherapy/radiation), sleep disorder, and possibly feigning the condition. 

Professional Takeaways

Since the year 2000, considerable advancements have been made in our clinical understanding of ADHD, including comprehending the neuroscience and genetic factors involved with this condition, its presentation and influence on development and functioning over the course of a lifespan, and the financial costs to our society. As a result of this knowledge and valid methodology, ADHD treatment methods have become more reliable.

That said, clinical assessment approaches to ADHD diagnosis remain a work-in-progress. In addition to the suggestions cited in this article to improve ADHD evaluations, forthcoming tools aim to delineate cultural and gender influences in ADHD presentations, recognize differences in the manifestation of ADHD over the lifespan, include questions about sleep disturbance (given the strong correlation), and encourage a shift to digital platforms. Digital technologies such as virtual reality for continuous performance tests, for example, may soon improve the ecological validity (eg, immersing one in a school or work environment) of assessment and potentially capture valuable and objective data involving head movement and visual scanning, thereby augmenting the sensitivity and specificity of ADHD assessment measures.

Part 2 of this special report will dive into what’s on the horizon for ADHD assessments.

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Last Updated: Jun 15, 2021