Is ADHD a Mental Illness? What Kind of Condition ADHD Is

Short answer: ADHD is a neurodevelopmental condition — it begins in early childhood and relates to how the brain develops.¹ It is classified in the DSM-5 alongside other mental disorders, and Australia’s national mental health surveys count it as one,² but it isn’t an illness that comes and goes. It isn’t autism, a learning disability or an intellectual disability, although it often occurs alongside them.

Is ADHD a mental illness?

Yes and no. In the DSM-5 — the manual clinicians use to diagnose mental disorders — ADHD is classified as a neurodevelopmental disorder, with onset typically before age 12.³⁴ The American Psychiatric Association describes it as one of the most common mental disorders affecting children,⁵ and Australia’s national child and adolescent mental health survey found it was the most common mental disorder among 4–17-year-olds.²

What sets ADHD apart from conditions such as depression or anxiety is that it’s present from childhood and relates to brain development, rather than an episode that begins later in life. It does often occur alongside them: the Australian ADHD Guideline notes that anxiety, depression and substance use problems may be a consequence of undiagnosed or untreated ADHD.⁶

Is ADHD a neurological condition?

ADHD is usually described as neurodevelopmental rather than neurological. The Senate inquiry into ADHD described it as a chronic and complex neurodevelopmental condition.⁷ For the Disability Support Pension, Services Australia’s impairment tables assess ADHD under Table 7, which covers neurological and cognitive function.⁸

Is ADHD neurodivergent?

Yes. “Neurodivergent” describes people whose brains work differently from what’s considered typical. healthdirect, the Australian Government’s health information service, notes that the term covers people with conditions such as dyslexia and ADHD as well as autism.⁹ Some people with ADHD identify as neurodivergent or as part of the disability community, and some don’t.⁷

Is ADHD on the autism spectrum?

No. ADHD and autism are separate conditions with separate diagnostic criteria, but some of their features overlap.⁹ They often occur together: around 30–60% of autistic children meet the criteria for an ADHD diagnosis.¹⁰ When someone has both, it’s sometimes called AuDHD — see ADHD and autism (AuDHD).

Is ADHD a learning disability?

Not in the specific sense. A specific learning disability — such as dyslexia — means significant difficulty in an area like reading, writing or maths in someone of average or above-average intelligence.¹¹ ADHD is a different condition, although learning difficulties often occur alongside it.¹

ADHD can still affect learning, and the law treats it accordingly. The Disability Discrimination Act’s definition of disability includes a disorder that results in a person learning differently,¹² and under the Disability Standards for Education 2005, schools, TAFEs and universities must make reasonable adjustments for students with disability.¹³

Is ADHD an intellectual disability?

No. Intellectual disability relates to difficulty learning or understanding things¹⁴ and is diagnosed with formal testing that includes an IQ test.¹⁵ ADHD is diagnosed on patterns of inattention, hyperactivity and impulsivity, not on intelligence.

Australian disability systems treat the two separately. Intellectual disability diagnosed as moderate, severe or profound is on the NDIS list of conditions likely to meet the disability requirements, and ADHD is not;¹⁶ the Disability Support Pension assesses intellectual function under a different impairment table from ADHD.⁸

Is ADHD a disability?

Under Australian discrimination law, yes — ADHD is included in the Disability Discrimination Act 1992.¹⁷ That is separate from NDIS eligibility, which depends on how much a permanent impairment affects daily life. See is ADHD a disability in Australia? and does the NDIS cover ADHD?

Frequently asked questions

Is ADHD a mental illness?

ADHD is classified in the DSM-5 as a neurodevelopmental disorder, alongside other mental disorders, and Australian mental health surveys count it. But it begins in childhood and relates to how the brain develops, rather than being an illness that starts later or comes and goes.

Is ADHD neurodivergent?

Yes. Neurodivergent describes people whose brains work differently from what’s considered typical, and Australian Government health information uses it to describe people with ADHD, autism and dyslexia.

Is ADHD on the autism spectrum?

No. ADHD and autism are separate conditions, but they often occur together — around 30–60% of autistic children also meet the criteria for ADHD.

Is ADHD a learning disability?

Not in the specific sense — a specific learning disability such as dyslexia affects reading, writing or maths. But ADHD can affect learning, and disability discrimination law covers conditions that cause a person to learn differently.

Is ADHD an intellectual disability?

No. Intellectual disability is diagnosed with formal testing that includes an IQ test; ADHD is diagnosed on patterns of inattention, hyperactivity and impulsivity.

Next steps

Read what is ADHD? and is ADHD genetic?, or start with the free ADHD self-assessment.

This article is general information only and is not medical advice. Only a qualified health professional can diagnose ADHD. ADHD GP is a private telehealth clinic staffed by AHPRA-registered Australian GPs.

Book your ADHD assessment

References

1. healthdirect (Australian Government). Attention deficit hyperactivity disorder (ADHD). 2025. www.healthdirect.gov.au — ADHD is a neurodevelopmental condition that begins in early childhood; around 1 in 20 people in Australia has ADHD; it is partly genetic; an adult diagnosis requires evidence that symptoms began in childhood; learning difficulties can occur alongside it.
2. Young Minds Matter (Australian Child and Adolescent Survey of Mental Health and Wellbeing). Prevalence of mental disorders. 2015. youngmindsmatter.thekids.org.au — ADHD was the most common mental disorder in Australian 4–17-year-olds (7.4%).
3. Australian ADHD Professionals Association. About ADHD (Australian ADHD Guideline). 2022. adhdguideline.aadpa.com.au — ADHD prevalence is 6–10% in Australian children and 2–6% in adults; heritability 70–80%; symptoms are present before age 12 though diagnosis may come later; 60–86% show symptomatic persistence into adulthood.
4. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 2013. www.psychiatry.org — Diagnostic criteria for ADHD, including the five-symptom threshold for adults aged 17 and over.
5. American Psychiatric Association. What is ADHD?. 2022. www.psychiatry.org — ADHD is one of the most common mental disorders affecting children; symptoms must be present before age 12; an estimated 8.4% of children and 2.5% of adults have ADHD.
6. Australian ADHD Professionals Association. Australian ADHD Guideline — summary of recommendations. 2022. adhdguideline.aadpa.com.au — Recommends stimulants as first-line medication for adults with impairing ADHD and non-stimulants where stimulants are unsuitable; dose titration with monitoring of heart rate, blood pressure, weight, sleep, mood and anxiety; cognitive-behavioural interventions, coaching and lifestyle guidance; notes anxiety, depression and substance use may follow untreated ADHD.
7. Parliament of Australia — Senate Community Affairs References Committee. Assessment and support services for people with ADHD — Chapter 1. 2023. www.aph.gov.au — ADHD occurs in about 6–10% of Australian children and adolescents and 2–6% of adults; heritability is estimated at 70–80%; Deloitte estimated 814,500 Australians living with ADHD in 2019 at a cost of $20.42 billion.
8. Federal Register of Legislation. Social Security (Tables for the Assessment of Work-related Impairment for Disability Support Pension) Determination 2023. 2023. www.legislation.gov.au — Table 7 (brain function) is used for neurological or cognitive conditions and names ADHD among the conditions assessed under it; intellectual function is assessed separately under Table 9.
9. healthdirect (Australian Government). Autism. 2025. www.healthdirect.gov.au — The term neurodivergent also describes people with conditions such as dyslexia and ADHD; some features of autism overlap with ADHD.
10. Raising Children Network (Australian Government funded). Conditions that can occur with autism. 2026. raisingchildren.net.au — Around 30–60% of autistic children meet the criteria for an ADHD diagnosis.
11. Queensland Department of Education. Learning disabilities. 2026. education.qld.gov.au — Specific learning disabilities involve average or above-average intelligence with significant difficulty in a learning area such as reading, writing or maths.
12. Federal Register of Legislation. Disability Discrimination Act 1992 (Cth). 1992. www.legislation.gov.au — Definition of disability includes conditions affecting thought processes, perception, emotions or judgement.
13. Federal Register of Legislation. Disability Standards for Education 2005. 2005. www.legislation.gov.au — Education providers must make reasonable adjustments for students with disability, using the Disability Discrimination Act definition.
14. Australian Institute of Health and Welfare. People with disability in Australia — prevalence of disability. 2024. www.aihw.gov.au — Defines intellectual disability as relating to difficulty learning or understanding things, as a category distinct from other disability groups.
15. Raising Children Network (Australian Government funded). Intellectual disability. 2026. raisingchildren.net.au — A diagnosis of intellectual disability involves formal testing with an IQ test.
16. National Disability Insurance Scheme. Operational guideline — Applying to the NDIS (List A and List B conditions). 2026. www.ndis.gov.au — ADHD is not on List A or List B; decisions focus on impairments and functional impact rather than diagnosis.
17. Parliament of Australia — Senate Community Affairs References Committee. Assessment and support services for people with ADHD — Chapter 7: ADHD under the NDIS. 2023. www.aph.gov.au — ADHD does not appear on either NDIS condition list, but people with ADHD can become participants if they meet the disability requirements; 188 participants had ADHD as their primary disability in March 2023.

Sources were last checked on 5 October 2026. See all sources used on this site on our Sources page.