Approach

The diagnosis of attention deficit hyperactivity disorder (ADHD) is clinical and based on the collection of relevant information through screening questionnaires/rating scales and clinical history, not psychological testing.[33] The aim is to thoroughly evaluate past and current symptoms, as well as the extent of the associated functional impairment. In some locations, for example, the UK, national guidance recommends that the formal assessment of ADHD in adults should only be carried out by a mental health specialist trained in the diagnosis and treatment of ADHD.[4] ADHD symptom rating scales can identify current attentional impairment, but this impairment is not itself diagnostic of adult ADHD.[33]​ In practice they may be used as an initial screening tool, and/or as an adjunct to the diagnostic process (see Screening). Rating scale results may then be combined with the results of patient interview and assessment, information from secondary sources, and additional testing (psychological, medical), as applicable, in evaluating the adult patient for the diagnosis of ADHD.[69]

Retrospective collateral history

When specific attentional impairment is identified in an adult, the history of such impairment in childhood should be investigated, as it is essential to the diagnosis. The patient's own report is not usually sufficient for such history; a living parent or sibling should be identified to provide such history because patients over-report childhood symptoms of inattention compared with the parent report in about 40% of cases.[70] Written documentation from school reports may also help. If no third party is available to provide relevant data, confidence in the possible adult ADHD diagnosis is correspondingly weakened.

If current attentional impairment is present and childhood impairment (prior to 12 years of age) is identified, including a third-party report, the time course of such impairment should be assessed relative to any other comorbid psychiatric symptoms (most commonly mood and anxiety symptoms).

Assessment of psychiatric comorbidity

About 75% of adults with ADHD will have at least one other mental health disorder.[2] Assessment of psychiatric/neurodevelopmental comorbidity is an essential facet of diagnosis of ADHD (e.g., mood, anxiety, substance use, eating, sleep, and autism spectrum disorders). Identify all comorbidities before beginning treatment, in order to determine the best order of treatment; consider all items of the relevant diagnostic criteria during this.[1][3]

If mood and/or anxiety symptoms are found to correlate with attentional symptoms, then the diagnosis of adult ADHD should be placed lower on the differential tree. The specific mood or anxiety disorder should then be identified and treated first, with the adult ADHD diagnosis deferred until those comorbid conditions are resolved, if possible.

ADHD-related symptoms

These include:[3]

  • Inattention

    • May be slow to think and formulate due to distractions.

    • May formulate things in a long-winded and tangential way, getting lost in detail, and having difficulty making decisions.

    • May also demonstrate inability to shift attention for events that trigger their interests.

  • Hyperactivity

    • Adults do not typically present in the same way as children; hyperactivity often presents as a subjective feeling of inner restlessness and agitation, rather than overt hyperactivity.

    • May also present as excessive talking, ceaseless mental activity, not being able to relax properly, or needing drugs/alcohol to relax and/or sleep.

    • Hyperactivity may be temporarily relieved with sporting activities which may be pursued to excess, resulting in sustained injuries.

  • Impulsivity

    • May act without thinking, or blurt out things that inadvertently cause distress to others.

    • There are frequently negative consequences for relationships with family, friends, colleagues, and employers.

    • There may be impulsive spending or eating.

    • Closely related to impulsivity are ‘sensation seeking’ behaviours when patients may seek out excitement from novel or thrilling stimuli - this may result in reckless driving, sexual risks, and provocative behaviour leading to fights.

  • Excessive mind wandering

    • Adults with ADHD frequently report a distractible mental state and multiple unrelated thoughts that are constantly on the go and which jump from one to another.

    • There is no abnormality of content of thought in comparison to other mental health disorders, e.g., depression.

  • Emotional dysregulation

    • There is difficulty in self-regulating emotional states such as irritability, frustration, and anger.

    • May manifest as low frustration tolerance, temper outbursts, emotional impulsivity, and mood lability.

    • This is different to episodic symptoms seen in altered mood states such as depression or mania; in ADHD, emotional symptoms tend to reflect short-lived exaggerated changes, often in response to daily events, with rapid return to baseline within a few hours.

Impact on patients and their families

ADHD may contribute towards difficulties for patients across the lifespan, including learning difficulties, school or university dropout, underachievement at work, financial problems, problematic gambling and internet use, relationship problems, intimate partner violence, addiction, sexual risk taking including teenage pregnancy and sexually transmitted infections, suicidality, self-harm, and criminal justice system involvement.[24][71][72][73][74][75][76]

ADHD may present differently in girls and women than in boys and men; there may be lower levels of hyperactive/impulsive symptoms and less disruptive behaviour in females.[3] In girls and women, there are high levels of co-occurring symptoms/disorders such as low self-esteem, anxiety and affective disorders; symptoms of ADHD may be mistakenly attributed to comorbidities.[77] Females with ADHD may also be more effective at masking symptoms, although masking may become less effective during life transitions such as leaving school or starting work. Women with ADHD appear particularly vulnerable to mental health difficulties, compared with controls; this includes insomnia, suicidal ideation, generalised anxiety disorder and risky sexual behaviour.[78][79]

High-functioning adults with ADHD of both sexes may not present with a typical pattern of functional impairment in daily life due to adaptive or compensatory skills which may mask core features of ADHD. Some people may excel in certain areas of life (e.g., work) but are impaired in others (e.g., paying bills, household tasks, social relationships, etc.). These people may experience subjective distress from symptoms such as mental/physical restlessness, sleep problems, and emotional instability. Some people with ADHD may self-medicate with drugs such as cannabis or alcohol to reduce unpleasant or distressing symptoms.[3]

Semi-structured diagnostic interview

For diagnostic assessment, European guidelines recommend the use of a semi-structured diagnostic interview, in combination with clinical assessment.[3] Clinical assessment should consider all items of the diagnostic criteria.[1] An example of a semi-structured diagnostic interview is the Diagnostic Interview for ADHD in adults, third edition (DIVA-5).[3]

Neuropsychological testing

Patients with adult ADHD report clear cognitive problems, which can be attentional and/or related to impairment in executive functioning. These can be assessed by experts using neuropsychological batteries, which may reveal abnormalities in:

  • Matching of familiar figures (impulsivity)

  • Verbal fluency

  • Continuous performance tests/word-finding (sustained attention)

  • Set shifting (dividing and shifting attention)

  • Word recall (working memory).

Findings of more generalised cognitive impairment often occur with exaggeration of abnormality in attentional and working-memory areas.

Neuropsychological testing is not diagnostic, and its main utility is in identifying the presence of isolated attentional and working-memory impairment, compared with the general population.

For example, although attentional impairment can be present, the diagnosis may be ADHD, but it is not definitively so until the clinical history is further assessed.

Medical assessment

Medical testing can be used to assess for conditions that, suggested by history, may account for, or at least contribute to, difficulties with attention and organisation/planning. These can include urine drug screening to evaluate for substance use, blood screening for hyperthyroidism, electroencephalogram to evaluate for seizure disorder, polysomnography to evaluate for a sleep disorder, and brain imaging in cases of head trauma (whether a recent or distant event).[80]

A baseline physical health assessment is recommended by UK guidance before starting medication for ADHD, including:[4]

  • Medical history

  • Current medication

  • Height and weight

  • Baseline pulse and blood pressure

  • Cardiovascular assessment

People with preexisting heart disease, symptoms suggestive of heart disease (e.g., syncope, palpitations, chest pain, post-exercise symptoms, heart murmur heard on auscultation, signs of heart failure), or a strong family history for sudden death should be referred to a cardiologist for examination before a stimulant trial.[4] There is no need to obtain routine ECGs or echocardiograms for healthy patients receiving stimulants.[4]

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