ADHD is actually more common than you might realise. It was first described about 100 years ago and is no more prevalent now, just better recognised. 

ADHD is the most common neurodevelopmental condition in children and adolescents. ​​In New Zealand, an estimated 280,000 Kiwis have ADHD. Studies in several countries have found that the prevalence rate of ADHD in children and adolescents is 6–8 per cent, with the highest figures generated from the US, where it may be up to 11%. A prevalence rate of 2.5-4% has been found for adults.

The treatment gap

Despite an increase in people being assessed for, and diagnosed with, ADHD there remains a treatment gap. Although not all people diagnosed with ADHD choose to take medications, (there are many other effective treatment strategies as detailed elsewhere on these pages), there is a wide disparity between the prevalence figures above and the numbers of people dispensed medication for ADHD.

Over time the dispensing rate for New Zealand European groups has increased more rapidly compared to Māori, Pacific, and Asian groups. There is concern that this may reflect particular barriers to receiving ADHD diagnosis and treatment for these populations. 

Although the number of adults seeking a diagnosis of ADHD has increased over time, there is concern it remains under-diagnosed in this population group too. This may relate to historical beliefs that ADHD only affected children, significant barriers in being able to access assessments, as well as adults with ADHD often having co-occurring conditions that may mask the symptoms of ADHD. 

ADHD and gender

Although ADHD is thought to be common across genders, you are more likely to receive a diagnosis if you are male. In childhood, although population studies find 2.5 times more boys meet criteria than girls and other genders, in clinical studies four times more actually receive a diagnosis.

If you are female or another gender, ADHD may be overlooked or diagnosed later. There are various reasons behind this, including that women and other genders tend to present with the inattentive subtype of ADHD, rather than its more striking hyperactive/impulsive features. 

Puberty-related changes in sex hormones may also lead to ADHD symptoms becoming more apparent. There is also evidence that, while women and other genders may be better at ‘masking’ impairment in childhood, the ability to do this can decline with age. 

What causes ADHD? 

A large proportion of the risk for developing ADHD relates to heritability, as 70-80% of the chance that you develop ADHD will be dictated by your genes.

Approximately 25% of all children with ADHD will have a parent with ADHD.

Around 35% of children of adults with a diagnosis of ADHD may also be meet criteria for a diagnosis themselves.

Other factors that can relate to the development of ADHD may include:

• exposure to drugs (especially tobacco) and alcohol before being born
• being born premature or of a low birth weight.
  

It is important to be clear that the development of ADHD in no way relates to parenting - in fact, supportive parents are one of the most effective ways to help childhood ADHD.

Content updated 26 March 2026 with support from child and adolescent psychologist David Chinn

* Australasian ADHD Professionals Association, Australian Evidence-Based Clinical Practice Guideline For Attention Deficit Hyperactivity Disorder (ADHD), First edition, June 2022, p 67, sourced online November 2022

**Additude Magazine, ADHD Statistics: New ADD Facts and Research, updated 13 July 2022, sourced online 12 April 2023

^ The University if Auckland, Whāraurau, 2020 Stocktake of the Infant, Child and Adolescent Mental Health, Alcohol and Other Drug Services in New Zealand, p 13, 2021, sourced online 14 March 2023​

^^ Margaret H. Sibley, Ph.D., L. Eugene Arnold, M.D., James M. Swanson, Ph.D., Lily T. Hechtman, M.D., Traci M. Kennedy, Ph.D., Elizabeth Owens, Ph.D., Brooke S.G. Molina, Ph.D., Peter S. Jensen, M.D., Stephen P. Hinshaw, Ph.D., Arunima Roy, Ph.D., Andrea Chronis-Tuscano, Ph.D., Jeffrey H. Newcorn, M.D., Luis A. Rohde, M.D., Ph.D., for the MTA Cooperative Group, Variable Patterns of Remission From ADHD in the Multimodal Treatment Study of ADHD, The American Journal of Psychiatry, August 2021