When we hear "ADHD," many of us picture a hyperactive child struggling to sit still in a classroom. However, attention-deficit/hyperactivity disorder (ADHD) doesn’t magically disappear with age. For many people, ADHD is a lifelong condition that shapes careers, relationships, and self-perception in ways that often go unnoticed. Yet, adult ADHD remains widely misunderstood, underdiagnosed, and stigmatised. Let’s explore the complexities of adult ADHD, from its persistence into adulthood to the barriers to diagnosis and care.

What is ADHD?
Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition, meaning it originates in childhood and impacts the development of brain function. In Australia, approximately 5–7% of children and 2–4% of adults are impacted by ADHD¹. It is characterised by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with daily functioning and development. Recognised by the DSM-5, it manifests in three types:

🔹 Predominantly Inattentive Type: Difficulty focusing, organizing tasks, and following through.

🔹 Predominantly Hyperactive-Impulsive Type: Restlessness, excessive talking, and hasty actions.

🔹 Combined Type: A mix of both inattentive and hyperactive-impulsive symptoms.

Historically, ADHD was viewed as a condition that primarily affected children, with the belief that individuals would "outgrow" it. However, it is now recognised as a lifelong condition that can persist into adulthood. While some individuals are diagnosed in childhood, others may not become aware of their symptoms until adulthood—or may remain undiagnosed throughout their lives.

How Is ADHD Diagnosed in Adults?

ADHD in adults is diagnosed through a comprehensive evaluation that includes a clinical interview, symptom checklists, and behavioural questionnaires. Symptoms like inattention, impulsivity, and hyperactivity, which may appear differently in adults than in children, are discussed in detail. Other conditions that could cause similar symptoms are ruled out, and feedback from family members or colleagues may be gathered. The diagnosis also considers how these symptoms impact daily functioning, work, and relationships.

Why ADHD Is Often Missed in Adults
Although ADHD is typically diagnosed in childhood, growing evidence shows that many individuals, particularly women and those with predominantly inattentive symptoms, may remain undiagnosed until later in life. This is because symptoms can appear differently as people age (e.g., restless fidgeting in children might become inner restlessness or burnout in adults; hyperactivity can be internalised due to societal gender expectations, manifesting as a mind that never seems to quiet down). Additionally, overlapping symptoms (e.g., depression, anxiety and trauma) can sometimes overshadow the ADHD diagnosis, leading it to be missed.

Impacts of Undiagnosed Adult ADHD
Undiagnosed ADHD can lead to ongoing challenges in work performance, time management, and relationships, often misinterpreted as personal failings rather than brain-based differences. This can significantly affect self-esteem, as individuals with ADHD may internalise negative labels like 'lazy or stupid.' These beliefs often stem from struggles with motivation, task initiation, and focus, which are characteristic of ADHD. Constantly facing difficulties without understanding the underlying cause can lead to feelings of inadequacy, shame, and frustration, further diminishing self-worth⁴.

Should You Consider an ADHD Assessment?

If you’ve always felt like you’re "running on a different operating system," it might be worth exploring ADHD. Adult ADHD is a complex, often misunderstood condition that can have a significant impact on many aspects of life. Recognising signs of ADHD in yourself and seeking a professional assessment can be an important step toward understanding and managing the condition. Early diagnosis and treatment can provide you with the tools and strategies needed to improve your quality of life, enhance personal and professional relationships, and empower you to live authentically.