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 spectrum. Particularly in children, 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 testing, we have been able to gain a better understanding of the way ADHD affects cognition, for example working memory, emotion regulation and executive function (the so called conductor of the brain orchestra). 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 or 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 greater understanding of the way ADHD interacts with the functioning of the brain.

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

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]

Our ADHD Blogs

Tricyclic antidepressants for ADHD in children and adolescents: Cochrane review finds no evidence to support prescribing


Helge Hasselman summarises a Cochrane review of tricyclic antidepressants for attention deficit hyperactivity disorder (ADHD) in children and adolescents, which finds low quality evidence and no justification for prescribing these drugs in this group of patients.

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Are autism and ADHD associated with antidepressants or maternal depression? The debate continues…


Amy Green summarises a retrospective observational study that finds prenatal antidepressant exposure is associated with risk for ADHD, but not autistic spectrum disorders. She considers this complex topic and works out what it all means for pregnant women with depression.

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Meta-review presents the risks of all-cause and suicide mortality in mental disorders


This recent and well-conducted meta-review concludes that the impact on mortality and suicide of mental disorders is substantial, and probably poorly appreciated as a public health problem. Raphael Underwood’s blog summarises the data for all-cause and suicide mortality in mental disorders.

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Children of older fathers have an increased risk of psychiatric and academic problems, says new cohort study


Research suggests that the risk of developing psychiatric problems (such as autism spectrum disorder, intellectual disability or schizophrenia) may be linked to increased paternal age at the time of conception. This seems quite plausible given that advancing age in men is associated with increased genetic mutations in sperm. However, studies so far have generally not [read the full story…]

ADHD and the importance of healthy sleep

child sleeping on school books

Good sleep is a crucial part of our physical and mental well-being. We typically spend about a third of our lives asleep but when we miss out on sleep, we can feel fatigued and struggle to concentrate. Sleep problems are generally quite common and have been reported as one of the most common health conditions [read the full story…]

Atomoxetine for adult ADHD: the harms outweigh the benefits, according to new systematic review


Attention Deficit Hyperactivity Disorder (ADHD) is a developmental neurological condition affecting functioning in a number of domains, but in particular, the ability to focus and concentrate, and regulate activity levels.  This is a common disorder with 2.5-4.0% of adults meeting diagnostic criteria for ADHD (Fayyad et al, 2007), and this condition has significant impact on a persons [read the full story…]

Estimating heritability in 5 psychiatric disorders: a 21st Century family study


It has long been established that psychiatric disorders have a genetic component. In the early days of genetic research, twin and family studies were used to estimate heritability (the proportion of variance explained by genetic factors). The Psychiatric Genetics Consortium has recently published a paper in Nature Genetics to assess the heritability and co-inheritability (relationship between [read the full story…]

Cohort study links early exposure to intimate partner violence with poor mental health outcomes, but longer follow-up is needed

family fighting

Negative childhood experiences have always been a big topic in psychology and psychiatry, as they tend to be associated with poor mental health outcomes in later life. Intimate partner violence (IPV) harms not only the adults directly involved in it, but also the children – witnessing IPV as a child is a known risk factor [read the full story…]

Cutting across diagnostic categories: Does stimulant medication improve ADHD symptoms in children with autism spectrum disorder?

Young girl with pills

Until fairly recently, it was thought that autism spectrum disorder (ASD; previously known as PDD or pervasive developmental disorder) and attention deficit hyperactivity disorder (ADHD) were two entirely separate childhood-onset conditions and that they could not both be diagnosed in one individual. Numerous studies in the last decade have shown that, in reality, a number of [read the full story…]

Systematic review of dropout rates from clinical trials of methylphenidate for adult ADHD


Attention deficit hyperactivity disorder (ADHD) is characterised by inattention, excessive activity levels and impulsive behaviours. Although it is an early developmental condition and is associated with childhood, in many instances, it is a lifelong condition. ADHD in adulthood is increasingly being recognised. Clinical guidelines and research suggest that the stimulant drug methylphenidate can reduce ADHD [read the full story…]