Attention Deficit Hyperactivity Disorder (ADHD) causes in-attention and hyperactivity and makes it hard for sufferers to control their behaviour. ADHD appears in pre-school and can continue into adulthood. Behavioural problems lead to symptoms such as fidgeting, short attention span, being restless and easily distracted.

What causes Attention Deficit Hyperactivity Disorder (ADHD) is not completely understood but many myths surround the condition. There is no evidence to suggest that poor parenting or stresses trigger the condition but they can exasperate it. The possible causes of ADHD are outlined below.

Hereditary/Genetic causes - In most cases, inheriting ADHD is the likely cause as the condition can run in families. It is four to five times more likely that parents of a child with ADHD will have the condition themselves.

Chemical imbalance and brain function – Chemicals that carry messages around the brain, known as neurotransmitters, have been found to not function properly in people with ADHD. Also, levels of dopamine and noradrenaline chemicals in the brain can be imbalanced in people with the condition.

The areas of the brain that control attention and activity have been found to display less function in people with ADHD. Research into the frontal lobe of the brain  – which controls decision making –  has found this area not to function properly in those with the condition.

Exposing a baby to toxins while pregnant – During pregnancy, if a woman continues to smoke, drink alcohol excessively or take drugs they increase the likelihood of giving birth to a child with ADHD (as well as many other disorders).

Being a boy – Although both sexes can be diagnosed with ADHD it is more common among boys than girls. If diagnosed during adulthood, the condition is also more likely among men than women. Research suggests the increased diagnosis of ADHD among males is because symptoms of the condition are more noticeable (such as hyperactivity, disruptive or loud aggressive behaviour). Girls have a tendency to only display inattentiveness and this condition is defined as Attention Deficit Disorder (ADD).

Television stimulus – TV is not a cause of ADHD but some research suggests that excessive watching of television at a young age may contribute to problems with attention which can lead to ADHD as the child grows.


Intolerance to certain foods – Studies have shown that common food allergies to milk, wheat and nuts may be linked with ADHD but food intolerance is not a direct cause. There's no evidence to suggest that sugar causes ADHD symptoms either but it may exasperate the symptoms.

Other causes – Premature birth, low birth weight and damage to the brain while in the womb may be possible causes of ADHD. Impaired hearing may also increase the risk of developing ADHD.

Symptoms of ADHD 

ADHD symptoms are placed into two groups of behaviour: inattentiveness, and hyperactivity and impulsiveness. Depending on the symptoms, a person with ADHD is then defined into three subtypes: ADHD mainly inattentive, ADHD mainly hyperactive/impulsive or ADHD combined.

Mainly inattentive

• Being careless or failing to pay close attention to detail.
• Leaving tasks unfinished or unable to keep attention on certain activities.
• When being talked to, seeming not to listen to what is being said.
• Basic instructions not carried out such as completing homework or household chores.
• The behaviour above is not about confrontation or failure to understand instruction.
• Disorganised in daily tasks.
• Easily distracted.
• Forgetting things during the course of daily activities.

• Overly noisy when at play.
• Difficulty engaging with quiet activities.
• Leaving a seat when the situation calls to be sat down (especially in classrooms).
• Fidgety (hands and feet).
• Wriggles and squirms when seated.
• Answering questions before they've been completed.
• Failure to take turn or stand in line within a group situation.
• Interrupting conversations or other's games.
• Excessive talking when social restraint is called for.

Diagnosis of ADHD 

Although there is no single test to determine ADHD you should visit your GP who will refer you or your child to a specialist should you suspect there's a problem. Assessment is made by physical examination to rule out other possible underlying problems that are causing the symptoms. Problem-solving, memory and concentration tests can also help determine ADHD.

Child ADHD

A child diagnosis of ADHD is made using a strict set of criteria:

1). The child must display six or more of the inattentive symptoms or hyperactive/impulsive symptoms. Displaying more than six hyperactivity/impulsiveness symptoms but less than six of inattentiveness will result in a diagnosis of ADHD mainly hyperactive/impulsive.

2). Symptoms must have been present for six months continuously.

3). Symptoms should be present before the age of 7.

4). Symptoms should be present in two settings such as at home and at school. This will rule out reaction to authority of parents or teachers.

5). Symptoms are having a negative impact at an academic, social or occupational level.

6). Symptoms are not a difficult growing phase or part of a developmental problem or other condition.

Adult ADHD

With no definitive list to help with diagnosing adult ADHD it can be problematic determining the condition. Your GP will refer you to a specialist but a diagnosis can only be made if symptoms have been present since childhood. This can prove difficult for those unable to remember their childhood years or if there are no parents, family members or former teachers who are available to help provide the answers.

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