Attention deficit hyperactivity disorder (ADHD)

Attention deficit hyperactivity disorder (ADHD) is a condition which causes sufferers to display impulsiveness, inattentiveness and hyperactivity. In this article we will explain what ADHD is, the causes, risk factors, symptoms, diagnosis and treatment. You will find a useful summary section within each section of this article to help you identify the key information


What is ADHD❓

 ADHD stands for Attention Deficit (Hyperactivity) Disorder which is a neuro-developmental condition 🧠

 People with ADHD have differences in brain development and activity to the average person which can lead to behavioural issues such as issues with attentiveness and impulsiveness 🧠

 People with ADHD have difficulty with a group of key skills collectively known as executive function

 The three areas of executive function are working memory (the ability to store information in the mind and to use it), cognitive flexibility (the ability to think about something in many different ways) and inhibitory control (the ability to ignore distractions and temptation) ❌

 This may make it difficult for those with ADHD to pay attention, keep organised, start tasks and remain focused on them, manage their emotions and keep track of what they are doing. It may also make reflecting more difficult and slow down their processing speed ⌛

 This can in turn make everyday tasks difficult for those with ADHD


What are the different types❓

 There are currently three recognised subtypes of ADHD which are ADHD hyperactive, ADHD inattentive and ADHD combined type

1. ADHD hyperactive:

 Individuals with ADHD hyperactive usually display impulsive behaviour and a perceived lack of control 😞

 Individuals with ADHD hyperactive tend to be hyperactive, for example, they are often restless or irritable 😬

 This was once believed to be the only type of ADHD

2. ADHD inattentive:

 Was previously known as ADD

 Individuals with ADHD inattentive mainly have difficulty staying focus and attending to tasks without being distracted ❌

 They may get bored easily by daily mundane tasks and move between different activities 😴

3. ADHD combined type:

 Individuals with combined type ADHD display both symptoms of ADHD hyperactive and inattentive 😴


 As ADHD is a spectrum, people with ADHD hyperactive and inattentive are described as primarily hyperactive or inattentive as most of their symptoms may fit into one category but they may also have symptoms from another

 For example, an individual with primarily ADHD inattentive may be easily distracted and bored but may also fidget a lot 


Attention Deficit (Hyperactivity) Disorder is a neurodevelopmental condition categorized by behavioural issues with attentiveness, hyperactivity and impulsiveness. Those with ADHD have difficulty with executive function. There are currently three recognised subtypes of ADHD which are ADHD hyperactive, ADHD inattentive and ADHD combined type.


What are the causes❓

 Whilst the exact cause of ADHD is still not something we fully understand, there are a few factors that are thought to influence whether or not an individual may have ADHD 🧠

 There has been evidence to suggest that genetics may play a part in the likelihood of an individual has ADHD  👪

 The inheritance of ADHD is complex and unlikely to be due to a single genetic fault, scientists have found that the interaction between many genes and the environment may be what causes the symptoms of ADHD to manifest

 There is evidence to suggest that children with parents with ADHD and siblings who have ADHD are more likely to have ADHD themselves  👪

 It is estimated that the genetic contribution to ADHD is over 70% and whilst this displays a strong genetic link, an individual having ADHD does not automatically mean that their child will also have ADHD as genes linked to ADHD may be inherited but never activated ❌

 There is no evidence that ADHD is sex-linked and so both males and females can have ADHD and can pass it on to their children 👪   

 Research has found that there are many differences in the structure of the brains of those with ADHD and those without ADHD 🧠

 Some studies have found a difference in the size of certain areas of the brain and others suggest that those with ADHD have an imbalance in the level of neurotransmitters in the brain or that these neurotransmitters may not function properly 🧠

 There are some misconceptions about what causes ADHD

 There is no significant evidence to suggest that vaccines, social media, watching TV or poor parenting can cause ADHD 📱


There is no definite cause of ADHD it is likely that genetics play a significant role. There is an increased likelihood of those with relatives who have ADHD having the conditions themselves. There is also a link between brain structure and the likelihood of having ADHD. However, there is no link between vaccination, social media, TV or parenting and the likelihood of having ADHD.


What are the risk factors❓

 Certain groups of people may be at a higher risk of having ADHD, this includes:

 Those who were born prematurely (before the thirty-seventh week of pregnancy) 🤱

 Those born with a low birth weight 🤱

 Those suffering from epilepsy

 Those with brain damage (either in the womb or from severe head injury later in life) 🧠

 Those with different brain structure (either from birth or traumatic brain injury), some studies show that the frontal lobe (which is related to decision making) in those with ADHD is different to those without it 🧠

 Those with a blood relative with ADHD or another mental health disorder 👪

 Those exposed to environmental toxins in childhood such as heavy metals, pesticides solvents and neurotoxins as this can disrupt neurotransmitter and neuromodulator function 🧠

 Maternal drug use, alcohol use or smoking during pregnancy: studies show that pregnant women who smoke or abuse drugs and alcohol whilst pregnant are at a much higher risk of having a child with ADHD, this may be because drug abuse can reduce the neuronal activity of the baby and alter neurotransmitters 🤰

 Some research suggests that the DRD4 gene which affects dopamine receptors in the brain may play a part in the expression of ADHD and not everyone with ADHD has the DRD4 gene, inheritance of this gene may increase the risk of an individual having ADHD

 It was formerly thought that gender was also a risk factor, with three times as many males being diagnosed with ADHD as females. However, this may have been due to women with ADHD being largely undiagnosed or misdiagnosed with other mental health conditions. As ADHD is commonly associated with hyperactive symptoms, girls (who predominantly have the inattentive type of ADHD) may be missed in diagnosis ❌


Certain groups of people are at a higher risk of having ADHD. There are biological reasons for example, those with a blood relative with ADHD or with the DRD4 gene are more likely to have ADHD. There are also environmental reasons for example those with brain damage, those exposed to environmental toxins in childhood are at a higher risk of having ADHD. The conditions of pregnancy and childbirth also contribute to the risk of having ADHD with those born prematurely, with a low birth weight or exposed to maternal drug use during pregnancy having a higher risk of having ADHD.


What are the symptoms❓


 The symptoms of ADHD can be categorised into two sections, inattentiveness and hyperactivity and impulsiveness. The symptoms in children and teenagers are a bit different from the symptoms in adults.


Symptoms in children and teenagers:

 The symptoms are usually noticeable by age six, they must occur in more than one situation (for example at school and at home) 👧

The main symptoms of inattentiveness:

  1. short attention span ⌛
  2. easily distracted
  3. making careless mistakes
  4. appealing forgetful or losing things
  5. being unable to stick to tedious or time consuming tasks 😴
  6. seeming unable to listen to or carry out instructions 👂
  7. constantly changing activity or task
  8. difficulty organising tasks

The main symptoms of hyperactivity and impulsiveness:

  1. unable to sit still, especially in calm or quiet surroundings
  2. constantly fidgeting
  3. being unable to concentrate on tasks 😴
  4. excessive physical movement
  5. excessive talking 🗣
  6. being unable to wait their turn
  7. acting without thinking
  8. interrupting conversations
  9. little or no sense of danger❗

 These symptoms can lead to underachievement in school and poor social skills as well as problems with discipline


Symptoms in adults:

 In adults, the symptoms of ADHD are more difficult to define as there is less research into adult ADHD. As ADHD is a development disorder, adults must have had the condition as children 👩

 Some research suggests that hyperactivity decreases in adults while inattentiveness worsens and symptoms of adult ADHD also tend to be more subtle than symptoms of childhood 👧

Suggested symptoms of adult ADHD:

  1. carelessness and lack of attention to detail
  2. continually starting new tasks before finishing old ones
  3. poor organisational skills
  4. inability to focus or prioritise❗
  5. continually losing or misplacing things
  6. forgetfulness
  7. restlessness and edginess 😖
  8. difficulty keeping quiet, and speaking out of turn 🗣
  9. mood swings, irritability and a quick temper 😠
  10. inability to deal with stress
  11. extreme impatience
  12. taking risks in activities


ADHD symptoms are different in adults and in children with the symptoms in adults being less defined than those in children. The main symptoms can be split into inattentive symptoms and hyperactive and impulsive symptoms.



How is it diagnosed❓


Diagnosing in children:

 GPs cannot formally diagnose a patient with ADHD

 For children with ADHD, it would be good for a parent to speak to the teachers of the child about any behavioural issues before seeing the GP 🏨

 The GP may ask about the symptoms of the child, when the symptoms started and where the symptoms occur (for example do they occur at school and at home), how the symptoms affect the child’s daily life, if there’s a family history of ADHD or if they have been any significant events in the children’s life for example bereavement 

 The GP may then discuss other problems or symptoms of other conditions the child may have 👧

 If the GP thinks the child may have ADHD, it is not unusual for a period of watchful waiting to occur, lasting about ten weeks, where you see if the child’s symptoms improve, stay the same or worsen 📅

 The GP may then refer the child to a specialist for a formal assessment if the behaviour does not improve and if it is deemed to be affecting their daily life. Specialists include child psychiatrists, paediatricians and learning disability specialists 🏨

 The specialist will make the diagnosis after a detailed assessment which may include:

  1. physical examination to rule out any other explanations for the symptoms 🏨
  2. a series of interviews with the parent and/or child 👧
  3. interviews or reports from other significant people, such as partners, parents and teachers 👪

To be diagnosed with ADHD:

 The child must have six or more symptoms of inattentiveness, or six or more symptoms of hyperactivity and impulsiveness 🏨

 They must also have been displaying symptoms continuously for at least six months and have started to show symptoms before the age of twelve 📅

 The symptoms must be displayed in at least two different settings, must not be accounted for by another condition, must not just be due to a difficult phase and must make their life more difficult


Diagnosing in adults: 

 For adults, the GP will assess the symptoms and may refer the adult for an assessment if their symptoms began during childhood and have stayed since then, significantly affect their daily life and can not be explained by another mental health condition 🧠

 It is harder to diagnose ADHD in adults than in children as there is debate about whether the same lists of symptoms used for diagnosing children and teenagers can be applied to adults 👩

 In some cases adults are diagnosed with ADHD if they have five or more of the symptoms of inattentiveness, or 5 or more of the symptoms of hyperactivity and impulsiveness from the diagnostic criteria for children 👧



ADHD can not be diagnosed by a GP and is diagnosed by a specialist using a detailed assessment. ADHD is diagnosed differently in adults and in children. In children, six or more symptoms of inattentiveness or hyperactivity and impulsiveness must be displayed. In adults, they may be diagnosed with ADHD if they have just five or more of these symptoms.


How is it treated❓

 Whilst treatment is usually arranged by a specialist, the condition may be monitored by a GP. A combination of medicine and therapy is often the course of treatment.



 In the UK there are five types of medicine licensed to treat ADHD:

  1. methylphenidate  💊
  2. lisdexamfetamine  💊
  3. dexamfetamine  💊
  4. atomoxetine  💊
  5. guanfacine  💊


 The most commonly used medicine for ADHD

 It is a stimulant so works by increasing activity in the brain, namely in areas related to controlling attention and behavior 🧠

 Can be offered to those over the age of 5 with ADHD 👧

 Common side effects are: an increase in blood pressure and heart rate, appetite loss (which can lead to weight loss or gain), sleep issues, headaches, stomach aches and mood swings 💙


 Lisdexamfetamine is also a stimulant which helps improve concentration and reduce impulsive behavior ⬇

 May be offered to teenagers and children over the age of 5 with ADHD if at least six weeks of being treated with methylphenidate has not helped 👧

 Adults may be offered lisdexamfetamine as the first-choice medicine 💊

 Common side effects are: appetite loss (which can lead to weight loss or gain), aggression, drowsiness, dizziness, headaches, diarrhoea, nausea and vomiting 🤮


 Dexamfetamine is also a stimulant 💊

 It may be offered to those over the age of 5 with ADHD 👧

 Common side effects are: decreased appetite, mood swings, agitation and aggression, dizziness, headaches, diarrhoea, nausea and vomiting 🤮


 It's a selective noradrenaline reuptake inhibitor (SNRI) and not a stimulant 💊

 Works by increasing the amount of noradrenaline in the brain. Noradrenaline passes messages between brain cells so this can help with concentration and controlling impulses 🧠

 May be offered to those over the age of 5 if using methylphenidate or lisdexamfetamine is not possible 👧

 Common side effects are: increase in blood pressure and heart rate, nausea and vomiting, stomach aches, sleep issues, dizziness, headaches and irritability 🤮


 Ganfacine also enhances noradrenaline neurotransmission 🧠

 May be offered to teenagers and children over the age of 5 if using methylphenidate or lisdexamfetamine is not possible ❌

 Guanfacine should not be offered to adults with ADHD ❌

 Common side effects are: tiredness or fatigue, headache, abdominal pain and a dry mouth


 Therapy is effective in treating additional problems that may be alongside ADHD such as anxiety disorders or issues with social conduct

 Some of the therapies available are:


 Encourages the parent to discuss ADHD and its effects, it can help the patient understand what the diagnosis means and help them to cope with the condition ✅

Behaviour therapy: 

 Provides support for carers of children with ADHD (and sometimes teachers), it usually involves behaviour management

 Parent training and education programmes: specially tailored parent training and education programmes can help parents learn ways of engaging with their child and help parents understand how to improve the attention and behaviour of the child  👪

Social skills training:

 The patient takes part in role-plays with the aim of teaching them how to behave in social situations and helping them understand how their behaviour affects others

Cognitive behavioural therapy (CBT):

 A talking therapy which can help the patient manage their condition by changing how they think and behave. It can be carried out individually or with a group 🧠


ADHD can be treated using medications and therapies, a combination of medication and therapy is often the best course of action. Most medications are stimulants which work to stimulate certain parts of the brain related with attention and control whilst other medications focus on increasing the transmission of noradrenaline. Therapies can help to treat other issues alongside  ADHD like anxiety and help the patient understand what their diagnosis means.



  1. ADHD is a neuro-developmental condition which can lead to behavioural issues such as issues with attentiveness and impulsiveness.
  2. ADHD may be inherited or caused by differences in brain structure
  3. Risk factors for ADHD include family history, brain damage, pregnancy complications, maternal drug abuse and exposure to toxins
  4. Symptoms of ADHD include inattentiveness and hyperactivity and impulsiveness
  5. ADHD can only be diagnosed by a specialist using a detailed assessment
  6. ADHD is treated with therapy and medication

By Iyinoluwa Popoola 

About the author

The i-medics Editorial Team consists of Doctors, Medical Students, Professional Content writers, i-medics Ambassadors and Freelance workers.