Attention deficit/hyperactivity disorder, commonly known as ADHD, is the diagnostic name given to a persistent developmental condition, characterised by a set of behavioural symptoms falling broadly into problems with inattention, hyperactivity and impulsivity. To meet diagnosis, these symptoms should occur across a number of settings, and result in impairment to day-to-day living.

It is said that roughly 2-5% of young people are affected by ADHD, though the precise numbers are unclear. It is more frequently diagnosed in boys.

Although traditionally associated with children, ADHD can be diagnosed at any age, and recent research has highlighted the impact of ADHD in adults. Diagnosis, however, is most commonly made in children aged six and upwards.

Alongside symptoms of ADHD, people often report difficulties relating to low mood, anxiety and disturbed sleep.

Like many developmental and mental health conditions, the symptoms exist on a continuum. Periods of restlessness and inattentiveness are perfectly normal and do not necessarily indicate ADHD.

What we know already

Through longitudinal studies, we know that often the symptoms of ADHD can improve with age; however, many adults continue to experience difficulties.

Similarly, we know that ADHD is more common in people with learning disabilities.

Through advances in neuroimaging and neuropsychological assessment, we have been able to gain a better understanding of the way ADHD affects cognition (e.g. working memory and other executive function),emotion regulation and behaviour. Similarly, we have gained a better understanding of neurochemical factors, such as the role of dopamine uptake.

Evidence suggests that multimodal treatments (i.e. combination of medication and behavioural therapy) can be highly effective in the management of ADHD.

Areas of uncertainty

The causes of ADHD remain largely unclear, although there appears to be a clear hereditary component. Similarly, other factors such as low birth weight, premature birth, brain injury, toxic exposure at an early age, and environmental factors have all been suggested.

Due to the historical lack of research into disadvantaged groups, we know less about ADHD in ethnic minorities; however, this is improving. Similarly, only relatively recently have gender differences been convincingly explored.

There had been considerable research, of varying quality, into alternative treatments of ADHD. Long-chain polyunsaturated fatty acids, for example, have been shown to demonstrate small positive effects, however this area of research remains methodologically weak.

What’s in the pipeline?

As neuroimaging techniques improve, there will no doubt be a greater understanding of which aspects of brain functioning are associated with symptoms of ADHD.

Similarly, genetic (and other causal) factors continue to be explored, improving our understanding.

Such increases in understanding of the causes and mechanisms involved in ADHD are likely to lead to improved, targeted, interventions. Whilst multimodal treatments have been shown to be largely effective, the benefit often dissipates over time. Similarly, whilst some people continue to improve following treatment, others do not. Developing these treatments will likely remain a priority.


Gillies, D., Sinn, J. K., Lad, S. S., Leach, M. J. and Ross, M. J. (2012). Polyunsaturated fatty acids (PUFA) for attention deficit hyperactivity disorder (ADHD) in children and adolescents. Cochrane Database of Systematic Reviews. [Abstract]

Murray, D. W., Arnold, L. E., Swanson, J., Wells, K., Burns, K., Jensen, P., … & Strauss, T. (2008). A clinical review of outcomes of the multimodal treatment study of children with attention-deficit/hyperactivity disorder (MTA). Current psychiatry reports, 10, 424-431. [Abstract]


Written by: Patrick Kennedy-Williams
Reviewed by: Joff Jones, Anna Adlam
Last updated: Sep 2015
Review due: Sep 2016

Our ADHD Blogs

What is the evidence for ADHD as a risk factor for intimate partner violence or sexual violence?

multi coloured puzzle pieces painted onto a wall

In this co-written blog, Vishal Bhavsar and Janhvi Duggal explore a recent systematic review which looks at the relationship between ADHD and exposure to, and perpetration of, intimate partner violence and sexual violence.

[read the full story...]

What’s the link between neurodevelopmental or mental disorders and school absence or exclusion?


Chris Fielding summarises a Welsh cohort study which finds that neurodevelopmental and mental disorders are linked to school absenteeism and exclusion.

[read the full story...]

Youth mental health interventions: umbrella review presents efficacy and acceptability data


In his debut blog, Nick Meader tackles a huge umbrella review of youth mental health interventions, which presents the efficacy and acceptability of 72 different approaches to help children and young people.

[read the full story...]

ADHD is a substantial risk factor for poor academic performance, according to a new study from Norway #CAMHScampfire


Douglas Badenoch summarises a recent population-based study of ADHD deficit in school performance across sex and parental education, which has some interesting findings for parents, teachers and health professionals.

Join us around the #CAMHScampfire on Tuesday 27th September to discuss this paper.

[read the full story...]

Critiquing the evidence behind the “evidence-based conclusions” about ADHD


Shuichi Suetani and Gaj Panagoda explore the World Federation of ADHD International Consensus Statement published in 2021, which contains “208 evidence-based conclusions about attention-deficit hyperactivity disorder.

[read the full story...]

Caries in Children with Attention Deficit Hyperactivity Disorder

shutterstock_ADHD child

This review of whether children and adolescents with attention deficit with hyperactivity disorder (ADHD) had more dental caries than children and adolescents without ADHD included 13 observational studies. The findings suggest a higher risk of caries in children with ADHD Odds ratio = 3.31(95%CI; 1.25 to 8.73) and a significantly higher DMFT index Mean difference = 0.75 (0.38 to 1.13). However because of heterogeneity in the included study designs and a lack of adjustments for confounding factors the findings should be interpreted cautiously.

[read the full story...]

The global burden of disease from mental disorders remains high


Alejandro Arguelles Bullon summarises the latest Global Burden of Disease study (2019) looking at the prevalence, incidence and impact that mental disorders have on our lives, which shows no reduction in the burden over the last 30 years.

[read the full story...]

Behavioural therapies may reduce inattention symptoms in adults with ADHD


Shubhangi Karmakar summarises a systematic review on the effects and feasibility of psychological interventions to reduce inattention symptoms in adults with ADHD, which highlights significant uncertainty in the field.

[read the full story...]

ADHD: which medications are most effective and safe?


In his debut blog, Franco De Crescenzo summarises a narrative review that finds good evidence for the short-term pharmacological treatment of ADHD.

[read the full story...]

How common is mental illness in children aged 1-7 years old?


Jennifer Lau and Meenakshi Shukla explore a recent meta-analysis which finds that worldwide, 1 in 5 children aged 1-7 years old will experience a mental health condition.

[read the full story...]