Standardised ADHD questionnaires

To complement the clinical interview, it is extremely helpful to have standardised behaviour rating scales by the patient (if old enough), an observer (such as parent &/or partner) or if school-age, a teacher. Preferably these can be obtained prior to the clinical interview, so that the results can inform the direction of the interview as observers/teachers may have additional concerns that may need exploration to those the patient is aware of.

There are numerous standardised questionnaires that include ADHD symptom and impairment ratings including brief ratings that focus on ADHD symptoms (e.g. Conners Adult ADDH Rating Scales, ADHD Rating Scale-5, Brown Attention Deficit Disorder Scales, Clinical Assessment of Attention Deficit-Child), mid-length questionnaires approximately 50-100 questions (e.g. Conners 3 Rating Scales, ADHD Symptoms Rating Scale, Attention-Deficit/Hyperactivity Test- 2^nd Ed), and comprehensive questionnaires that include items for other disorders (Conners Comprehensive Behaviour Rating Scales, Behavior Assessment Scale for Children-2).

There are also several executive functioning questionnaires (e.g., Delis-Rating of Executive Function, Behaviour Rating Inventory of Executive Function, Comprehensive Executive Functioning Inventory) that are valuable in understanding the extent of the functional problems and devising a treatment .

Direct assessment of patient with ADHD

If the clinical interview and standardised questionnaires indicate significant issues with attention and/or hyperactive- impulsive behaviour, the next stage will be to formally assess the patient. The starting point will depend on the issues raised during the clinical interview (as summarized in the table above). If there is any evidence of medical issues; nutritional deficiencies; sleep problems; or language, vision or hearing impairments, it is important for these to be followed up as a priority.

Standardised assessment of attention and other core cognitive processing skills underlying the ADHD symptoms is highly debated in relation to clinical utility in the diagnosis of ADHD. Although ADHD, by definition, requires the presence of attention, hyperactivity or impulsivity impairments, there are no guidelines to actually assess it, and subjective behaviour ratings are considered the current benchmark (Barkley, 2015). The use of subjective ratings seems highly counterintuitive given that there exist many objective attention tests, and that research has shown that parent and teacher ratings in ADHD are only modestly correlated (Narad et al., 2014). Research has found that neuropsychological assessment, which identifies the precise cognitive issues underlying the attention problems, can lead to better initiation of treatment and promote better symptom reduction and improved quality of life due to more precise targeting of treatments (Pritchard et al., 2014).

Attention is an umbrella term to describe many different cognitive skills including visual sustained attention, auditory sustained attention, visual attention span, auditory attention span, visual selective attention, switching attention, and divided attention. Issues with any particular cognitive skill can create similar functional weaknesses, therefore testing only elements of attention is not likely to results in an adequate assessment of ADHD. Studies examining the cognitive profile of children with ADHD show that attention, executive functioning, working memory and information processing should be assessed to understand the core cognitive issues creating the functional attention problems (Barkley, 1997).

Observations

Classroom or workplace observations may be useful depending on the results from the clinical interview, behaviour ratings and formal testing, to make a differential diagnosis of whether the attention issues are being caused by a core cognitive issue (like ADHD) versus a different medical, processing or psychiatric condition. Alternatively, in some cases where there is a great discrepancy between different people's ratings, or a conflict between more subjective ratings and objective test data, clinical observations can help determine what is happening functionally, particularly in the classroom. Depending on the nature of the person's unique cognitive profile, some attention weaknesses may not present as obvious within the classroom setting. For example, if a student demonstrates strong visual attention but weak auditory attention, the student may appear focused but may not be listening, which may be overlooked by a teacher. Where possible, it can be helpful for observations to be conducted by the school psychologist who will be able to collect these data less intrusively than clinicians.

Differential Diagnosis, Potential Misdiagnosis, and Comorbid Conditions

The relationship between ADHD and various medical conditions has resulted in a controversial debate within the literature, and some researchers even argue that ADHD does not exist and it is actually a cluster of symptoms that may represent other disorders (Saul, 2014). It is generally recognised that ADHD can be misdiagnosed if other conditions that have similar attention problems are not ruled out as a possible aetiology, and that treatment should be targeted at the core condition causing the attention problems. Sometimes it can be challenging to distinguish between whether another condition (e.g., depression) is causing the ADHD symptoms or whether the symptoms would still be at clinical levels if the other condition was not present.

Children and adolescents with ADHD are significantly more likely to have one or more psychiatric disorders, with the most common comorbidity being oppositional defiant disorder (30-90%; Rydell, 2010). Other comorbid disorders include conduct disorder (24-27%; Larson et al, 2011), Tourette’s syndrome (25-85%; Geller et al, 1996), tic disorder (20%; Banaschewski et al, 2007), bipolar disorder (22-24%; Gillberg et al, 2004), depressive disorders (14%; Larson et al, 2011), and anxiety disorders (18-50%; Larson et al, 2011). Up until the publication of the DSM-5 in 2013, ADHD and autism spectrum disorders (ASD) could not be diagnosed as comorbid; however, roughly 20-50% of children with ADHD meet the criteria for ASD whilst 30-80% of patients with ASD meet criteria for ADHD (Rommelse et al., 2010).

In regards to the comorbidities with other processing problems, there is considerable co-occurrence between ADHD and learning disorders (10-50%; Margari et al, 2013), language disorders (45%; Hutchinson et al, 2012), speech problems (12%; Larson et al, 2011), reading disorder/dyslexia (18-45%; Margari et al, 2013) and executive dysfunction (33%; Biederman et al, 2004). When other processing issues are present, it is important to ensure that there is a core attention weakness, rather than the main processing weakness subsequently creating functional issues with attention. For example, a student with a receptive language disorder may not be able to sustain focus in the classroom due to the high language demands, but the student may have intact auditory and visual attention skills when the language component is reduced.

Visual processing disorders and auditory processing disorders are also hard to distinguish from ADHD due to the subsequent attention problems associated with these disorders.  For example, children with convergence insufficiency have many symptoms of ADHD due to difficulties maintaining eye focus on targets (Damari, Liu & Smith, 2000). Symptoms of a variety of eye disorders involving eye teaming and oculomotor problems have also been shown to be misdiagnosed as ADHD (Damari et al, 2000). Likewise, auditory processing disorders can produce symptoms of what appears to be inattention in noisy settings such as a classroom or on sporting fields. Even a simple differential diagnosis between ADHD and learning problems can be difficult, as children with delayed learning may become inattentive in the classroom when presented with work beyond their capabilities.