The NHS describes 'Attention deficit hyperactivity disorder (ADHD) is a condition that affects people's behaviour. People with ADHD can seem restless, may have trouble concentrating and may act on impulse .
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.