Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that causes inattention and/or hyperactivity and impulsivity that interferes with a person’s day-to-day activities or development.
Inattention is characterised by wandering off task, having difficulty sustaining focus, disorganisation and lacking persistence.
Hyperactivity refers to excessive motor activity, such as fidgeting, tapping or talkativeness.
Impulsivity refers to hasty actions that have the potential to harm the individual. These could include being socially intrusive (interrupting others excessively) or making important decisions without consideration of consequences.
ADHD usually begins in childhood and the manifestations of illness occur across multiple settings, such as at school and home. Signs of illness may not be present when an individual is engaged in interesting activities; has consistent external stimulus; or is receiving frequent rewards for appropriate behaviour. The condition persists into adulthood for a significant proportion of people (estimated up to 60% of cases). The possibility of late (adult) onset illness is controversial with mixed results from research studies.
The prevalence of ADHD
Population surveys suggest ADHD occurs in most cultures, with a global prevalence of 2.6%.1 However, prevalence rates are lower in resource-poor settings, and higher in resource-rich settings. Research indicates the prevalence of ADHD among Australian children and adolescents is around 6–10%.
In 2013–14, the prevalence of ADHD among Australian:
- children aged 4 to 11 was estimated at 10.9% in boys and 5.4% in girls (8.2% overall)
- adolescents aged 12 to 17 was estimated at 9.8% in boys and 2.7% in girls (6.3% overall).2
ADHD is strongly genetic. There are also environmental risk factors, such as maternal smoking and low birthweight. The socioeconomic and educational background of parents are also important risk factors for children. Around two-thirds of people with ADHD have a co-occurring psychiatric disorder, such as anxiety and mood disorders, substance use disorders and conduct disorders.
ADHD is associated with social, criminal and financial problems. These problems include higher experience of academic failure, self-esteem difficulties, relationship challenges, injuries, substance use and negative interactions with the criminal justice system.
References
- Song P, Zha M, Yang Q, Zhang Y, Li X, Rudan I. The prevalence of adult attention-deficit hyperactivity disorder: A global systematic review and meta-analysis. J Glob Health. 2021;11:04009. doi:10.7189/jogh.11.04009
- Lawrence D, Johnson S, Hafekost J, et al. The mental health of children and adolescents: report on the second Australian Child and Adolescent Survey of Mental Health and Wellbeing. Department of Health; 2015. Accessed 29 August, 2025.