Symptoms of ADHD tend to be noticed at an early age and may become more noticeable when a child’s circumstances change, such as when they start school. Most cases are diagnosed when children are 6 to 12 years old.

The symptoms of ADHD usually improve with age, but many adults who were diagnosed with the condition at a young age continue to experience problems.

People with ADHD may also have additional problems, such as sleep and anxiety disorders.

The exact cause of ADHD is unknown, but the condition has been shown to run in families. Research has also identified a number of possible differences in the brains of people with ADHD when compared with those without the condition.

Other factors suggested as potentially having a role in ADHD include:

  • Being born prematurely (before the 37th week of pregnancy).
  • Having a low birthweight.
  • Smoking, or alcohol or drug abuse during pregnancy.

ADHD can occur in people of any intellectual ability, although it’s more common in people with learning difficulties.

The symptoms of ADHD in children and teenagers are well defined, and they’re usually noticeable before the age of 6. They occur in more than one situation, such as at home and at school.


The main signs of inattentiveness are:

  • Having a short attention span and being easily distracted,
  • Making careless mistakes – for example, in schoolwork,
  • Appearing forgetful or losing things,
  • Being unable to stick to tasks that are tedious or time-consuming,
  • Appearing to be unable to listen to or carry out instructions,
  • Constantly changing activity or task,
  • Having difficulty organising tasks.

Hyperactivity and Impulsiveness

The main signs of hyperactivity and impulsiveness are:

  • Being unable to sit still, especially in calm or quiet surroundings,
  • Constantly fidgeting,
  • Being unable to concentrate on tasks,
  • Excessive physical movement,
  • Excessive talking,
  • Being unable to wait their turn,
  • Acting without thinking,
  • Interrupting conversations,
  • Little or no sense of danger.

These symptoms can cause significant problems in a child’s life, such as underachievement at school, poor social interaction with other children and adults, and problems with discipline.

Related Conditions in Children and Teenagers With ADHD

Although not always the case, some children may also have signs of other problems or conditions alongside ADHD, such as:

  • Anxiety disorder – which causes your child to worry and be nervous much of the time; it may also cause physical symptoms, such as a rapid heartbeat, sweating and dizziness.
  • Oppositional defiant disorder (ODD) – this is defined by negative and disruptive behaviour, particularly towards authority figures, such as parents and teachers.
  • Conduct disorder – this often involves a tendency towards highly antisocial behaviour, such as stealing, fighting, vandalism and harming people or animals.
  • Depression – sleep problems – finding it difficult to get to sleep at night, and having irregular sleeping patterns.
  • Autistic spectrum disorder (ASD) – this affects social interaction, communication, interests and behaviour.
  • Epilepsy – a condition that affects the brain and causes repeated fits or seizures.
  • Tourette’s syndrome – a condition of the nervous system, characterised by a combination of involuntary noises and movements (tics).
  • Learning difficulties – such as dyslexia.

Symptoms in Adults

In adults, the symptoms of ADHD are more difficult to define. This is largely due to a lack of research into adults with ADHD.

As ADHD is a developmental disorder, it’s believed it cannot develop in adults without it first appearing during childhood. But it’s known that symptoms of ADHD often persist from childhood into a person’s teenage years and then adulthood.

Any additional problems or conditions experienced by children with ADHD, such as depression or dyslexia, may also continue into adulthood.

By the age of 25, an estimated 15% of people diagnosed with ADHD as children still have a full range of symptoms, and 65% still have some symptoms that affect their daily lives.

The symptoms in children and teenagers are sometimes also applied to adults with possible ADHD. But some specialists say the way in which inattentiveness, hyperactivity and impulsiveness affect adults can be very different from the way they affect children.

For example, hyperactivity tends to decrease in adults, while inattentiveness tends to get worse as the pressures of adult life increase. Adult symptoms of ADHD also tend to be far more subtle than childhood symptoms.

Some specialists have suggested the following as a list of symptoms associated with ADHD in adults:

  • Carelessness and lack of attention to detail.
  • Continually starting new tasks before finishing old ones.
  • Poor organisational skills.
  • Inability to focus or prioritise.
  • Continually losing or misplacing things.
  • Forgetfulness.
  • Restlessness and edginess.
  • Difficulty keeping quiet, and speaking out of turn.
  • Blurting out responses and often interrupting others.
  • Mood swings, irritability and a quick temper.
  • Inability to deal with stress.
  • Extreme impatience.
  • Taking risks in activities, often with little or no regard for personal safety or the safety of others – for example, driving dangerously.

Related Conditions in Adults With ADHD

As with ADHD in children and teenagers, ADHD in adults can occur alongside several related problems or conditions.

One of the most common is depression. Other conditions that adults may have alongside ADHD include:

  • Personality disorders – conditions in which an individual differs significantly from the average person in terms of how they think, perceive, feel or relate to others.
  • Bipolar disorder – a condition affecting your mood, which can swing from one extreme to another.
  • Obsessive compulsive disorder (OCD) – a condition that causes obsessive thoughts and compulsive behaviour.

The behavioural problems associated with ADHD can also cause problems such as difficulties with relationships and social interaction.

There are 5 types of medication licensed for the treatment of ADHD:

  • Methylphenidate 
  • Dexamfetamine
  • Lisdexamfetamine
  • Atomoxetine
  • Guanfacine

These medications are not a permanent cure for ADHD but may help someone with the condition concentrate better, be less impulsive, feel calmer, and learn and practise new skills.

Some medications need to be taken every day, but some can be taken just on school days. Treatment breaks are occasionally recommended to assess whether the medication is still needed.

If you were not diagnosed with ADHD until adulthood, your GP and specialist can discuss which medications and therapies are suitable for you.

If you or your child is prescribed one of these medications, you’ll probably be given small doses at first, which may then be gradually increased. You or your child will need to see your GP for regular check-ups to ensure the treatment is working effectively and check for signs of any side effects or problems.

It’s important to let your GP know about any side effects and talk to them if you feel you need to stop or change treatment.

Your specialist will discuss how long you should take your treatment but, in many cases, treatment is continued for as long as it is helping.