Elsevier

The Lancet Psychiatry

Volume 3, Issue 6, June 2016, Pages 568-578
The Lancet Psychiatry

Series
Adult attention-deficit hyperactivity disorder: key conceptual issues

https://doi.org/10.1016/S2215-0366(16)30032-3Get rights and content

Summary

For many years, attention-deficit hyperactivity disorder (ADHD) was thought to be a childhood-onset disorder that has a limited effect on adult psychopathology. However, the symptoms and impairments that define ADHD often affect the adult population, with similar responses to drugs such as methylphenidate, dexamphetamine, and atomoxetine, and psychosocial interventions, to those seen in children and adolescents. As a result, awareness of ADHD in adults has rapidly increased and new clinical practice has emerged across the world. Despite this progress, treatment of adult ADHD in Europe and many other regions of the world is not yet common practice, and diagnostic services are often unavailable or restricted to a few specialist centres. This situation is remarkable given the strong evidence base for safe and effective treatments. Here we address some of the key conceptual issues surrounding the diagnosis of ADHD relevant to practising health-care professionals working with adult populations. We conclude that ADHD should be recognised in the same way as other common adult mental health disorders, and that failure to recognise and treat ADHD is detrimental to the wellbeing of many patients seeking help for common mental health problems.

Section snippets

Attention-deficit hyperactivity disorder (ADHD) as a lifespan disorder

ADHD is classified in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (5th edition; DSM-5) as a childhood-onset neurodevelopmental disorder, defined by the presence of developmentally inappropriate and impairing levels of inattention, hyperactivity, and impulsivity.1 Epidemiological surveys find that 5–6% of children meet DSM-IV criteria for ADHD,2, 3 with a slightly higher prevalence expected when DSM-5 criteria are applied.4 Meta-analysis of

The diagnostic construct of ADHD

For many years, researchers have argued that most mental health disorders reflect the extreme and impairing tail of one or more continuously distributed traits. Present research strategies, such as the Research Domain Criteria (RDoC), increasingly focus on delineating the underlying neurobiological substrates that underpin dimensions of psychopathology.20 Among these, ADHD is one of the best examples in which no point of rarity can be found in the distribution of ADHD symptoms and impairments

Rater effects and measurement of ADHD symptoms

One factor complicating the assessment of ADHD is the change in informant during development. Throughout most of childhood and early adolescence, the primary informants for diagnostic information are parents and teachers, who report mainly on the basis of observed behaviours. For this reason, the ADHD symptoms listed in DSM-IV/5 and International Classification of Diseases (10th edition; ICD-10) are largely descriptions of observed behaviours rather than subjective reports of mental state

Cognitive and neuroimaging markers of ADHD

Cognitive performance measures of attention and impulsivity have been suggested in neurocognitive studies as markers of ADHD symptoms, with several companies marketing different versions of continuous performance tasks (sustained attention and inhibitory control tasks that measure errors of omission, commission, and reaction time). The assumption made is that omission errors reflect behavioural inattention, commission errors reflect behavioural impulsivity, and reaction time variability

Characteristic features of ADHD that support the diagnosis

Focus on the mental state of adult patients with ADHD has been of more immediate clinical value than the use of cognitive or neuroimaging data. Symptoms such as feeling physically restless, emotional dysregulation, excessive mind wandering, and sleep-onset insomnia are all clinically relevant symptoms that are commonly seen in adult ADHD. Surprisingly, these symptoms are not well studied in ADHD despite their potential value in clinical practice.

Course and outcome

Reasons for the persistence and desistence of ADHD into adulthood are not well understood, but are of considerable interest because they identify potential targets for early prevention and treatment. Factors influencing course and outcome include general cognitive ability, severity of ADHD, causal factors (genes and environment), brain maturation and development, and the presence of co-occurring mental health and neurodevelopmental disorders.33 Protective factors, such as exercise,72 might also

Adult-onset ADHD: a potential new trajectory for the disorder

ADHD has been traditionally conceptualised as a neurodevelopmental disorder and is included under this umbrella term in DSM-5.1 Although some disorders known to have a neurodevelopmental trajectory, such as schizophrenia, do not necessarily begin in childhood, ICD-10 clearly defines that a neurodevelopmental disorder should have an onset during infancy or childhood. Thus, it is not surprising that age-of-onset during early childhood emerged as a key element in the definition of ADHD. However,

ADHD, treatment, and comorbidity

One reason for the under-diagnosis of ADHD by adult mental health services is the nature of the clinical syndrome, which shares characteristics with other common adult mental health disorders. These include clinical features associated with adult ADHD that do not form part of the present DSM-5 or ICD-10 diagnostic criteria. Examples include poor concentration, distractibility, restlessness, over-talkativeness, sleep problems, irritability, impulsiveness, and low self-esteem. However, in this

Conclusions

We conclude that ADHD should be recognised in the same way as other common adult mental health conditions, and that failure to recognise and treat ADHD is detrimental to the wellbeing of many patients seeking help for mental health problems. Although further research is needed to assess the effects of ADHD drug treatments in ADHD complicated by comorbidities, effective clinical management of ADHD should be an essential component of adult mental health care. A list of key points and research

Search strategy and selection criteria

Two approaches were taken. First, to cite the most established findings that have been replicated or demonstrated in systematic reviews and meta-analyses. Second, to highlight new emerging findings that require further research to confirm or refute initial findings. The text clarifies which of the newly emerging findings require further research.

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