ADHD is a diagnosis applied to children and adults who consistently display certain characteristic behaviours over a period of time. The most common core features include:

• Distractibility (poor sustained attention to tasks)
• Impulsivity (impaired impulse control and impaired delay of gratification)
• Hyperactivity (excessive activity and physical restlessness)

In order to meet diagnostic criteria, these behaviours must be excessive, long-term, and pervasive. The behaviours must appear before age 7, and continue for at least 6 months. A crucial consideration is that the behaviours must create a real handicap in at least two areas of a person's life, such as school, home, work, or social settings. These criteria set ADHD apart from the "normal" distractibility and impulsive behaviour of childhood, or the effects of the hectic and overstressed lifestyle prevalent in our society. 

According to the DSM-IV (the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) some common symptoms of ADHD include the following:

• often fails to give close attention to details or makes careless mistakes
• often has difficulty sustaining attention to tasks
• often does not seem to listen when spoken to directly
• often fails to follow instructions carefully and completely
• losing or forgetting important things
• feeling restless, often fidgeting with hands or feet, or squirming
• running or climbing excessively
• often talks excessively
• often blurts out answers before hearing the whole question
• often has difficulty awaiting turn

The exact nature and severity of ADHD symptoms varies from person to person.

Please note Dr Tanith Davidson does not diagnose ADHD. This must be done by an educational psychologist after an extensive evaluation. Dr Davidson does, however, treat ADHD and other behavioural and learning disorders.