ADHD
Adult ADHD explained: what it is, how common it is and how it is diagnosed
A plain-language guide to adult ADHD: what it is, how common it is, how a diagnosis works in general and what kinds of help exist. General information, with sources.
Adult ADHD is a neurodevelopmental condition: a long-standing difference in how the brain manages attention, impulses and activity, which begins in childhood and can keep causing real difficulty in adult life. It is not a character flaw, and it is not caused by laziness or poor parenting.
This guide explains in plain language what adult ADHD is, how common it is, how a diagnosis works in general and what kinds of help exist. It is general information, not a diagnosis. If you recognise yourself in it, the last section tells you where to go next.
What adult ADHD is
ADHD stands for attention-deficit/hyperactivity disorder. Clinicians describe three presentations: mainly inattentive, mainly hyperactive-impulsive, and combined [1]. Inattentive symptoms include trouble sustaining attention, losing track of things and being easily distracted. Hyperactive-impulsive symptoms include restlessness, interrupting others and acting before thinking.
Symptoms must have started in childhood. The NHS notes that they usually begin before the age of 12 [2]. Many people are still recognised only as adults, for example because they coped for years, or because nobody asked the right questions earlier.
The picture can also change over time. An international consensus statement reports that about one in six young people with childhood ADHD still meet the full criteria at 25, and about half have some remaining impairment [1]. So “I was fine at school” and “I still struggle” can both be true.
In everyday words, it can sound like this: “I lose things”, “I keep putting things off”, “I can’t stay in one place”, “I feel restless inside”, “my mind is buzzing”. None of these phrases proves ADHD on its own. They are the kind of concrete description that helps a clinician see the pattern behind the label.
How common is it?
A 2021 systematic review and meta-analysis estimated that about 2.58% of adults worldwide have persistent ADHD (symptoms that began in childhood and continue) and about 6.76% have symptomatic adult ADHD (current symptoms, whether or not they were obvious in childhood). Both figures fall with age [3]. The World Federation of ADHD consensus statement gives a similar overall estimate of about 2.8% of adults [1].
These are worldwide estimates. They show that adult ADHD is not rare, but they cannot tell you whether it applies to you. Only an individual assessment can do that.
What causes it?
ADHD runs in families. Research on genetics estimates its heritability at about 74%, with many genes each contributing a small part [4]. That is why ADHD is not explained by willpower or upbringing.
Struggling in an environment that does not fit the way your attention works is not failure. It is an expected reaction.
When is it worth asking for help?
The useful question is not “do I have some of these traits?” Most people recognise a few. The useful question is whether these difficulties systematically get in the way of work, study, relationships or daily life. That mirrors the diagnostic requirement of impairment [1]. We seek help when something systematically gets in the way of how we function, not merely when we feel discomfort.
Four questions help you put your own experience in order before an appointment:
Since when? Do you remember similar difficulties in childhood or adolescence?
Where? Do they appear in more than one setting, for example at home and at work?
What do they cost you? Think of jobs, studies, money, relationships, safety.
Could something else explain them better, such as anxiety, low mood or poor sleep?
Watch out for all-or-nothing conclusions in both directions. “I always mess everything up” is a conclusion, not a fact. Test it: if you miss one deadline and meet nine, is “always” accurate? The same goes for “everyone is distracted these days, so it cannot be ADHD”. The question is how much, since when and at what cost.
Safety is one concrete example of cost. If driving worries you, read our separate article on ADHD and driving.
How a diagnosis works, in general
A diagnosis is made by a qualified clinician in a clinical interview, not by an online test. The World Federation consensus states that ADHD cannot be diagnosed by rating scales alone, by neuropsychological tests or by brain imaging [1]. NICE guidance in the UK says the same about rating scales and asks for a full clinical and psychosocial assessment, a developmental and psychiatric history, observer reports and a mental state assessment [5].
The clinician checks that [1]:
symptoms have lasted at least six months;
they appear in different settings and cause impairment;
some symptoms began in early to mid childhood;
no other disorder explains them better.
A semi-structured interview such as DIVA is the recommended backbone of the assessment in the UK adult ADHD assessment standard. The interview uses open questions, because checklist-style assessments risk confirmation bias and missed alternative diagnoses. Questionnaires are useful as a baseline for later change, and an informant, ideally someone who knew you in childhood, is used whenever possible [6].
Other conditions are common alongside ADHD, in more than 60% of cases according to the same standard [6]. Having another condition does not rule ADHD out [1]. At the same time, ADHD should not be diagnosed when another condition explains the symptoms better [6]. Careful assessment protects you from mistakes in both directions.
The standard suggests at least about two hours of total contact time in most cases, in one or several sessions, including feedback and a discussion of options [6]. At this practice the assessment is a structured DIVA-5 interview, usually over two 45-minute sessions. The details, fees and booking are on the Adult ADHD service page. The assessment article explains what happens, and this one helps you prepare.
One combination deserves a mention: ADHD and autistic traits often occur together. That can explain why impulsivity and social difficulties appear side by side in the same person. So the assessment also asks about social communication, and when the history points towards autism, a specialist autism assessment may be suggested.
What helps, in outline
Help usually combines four things: understanding the diagnosis, practical adjustments to routines and workplace, psychological treatment such as CBT, and medication when there is a diagnosis and a clinical need. Medication should be started and monitored by a specialist [2]. NICE adds that psychological treatment should be considered when someone prefers not to take medication, or when medication helps only partly [5]. European consensus guidance states that effective evidence-based treatments exist and that ADHD is underdiagnosed and undertreated in many European countries [7].
Not everybody needs everything. Options are presented, and the choice is made together. Whether any medication is suitable is decided by the doctor after the appointment, never in advance.
One practical idea works whatever the plan. When energy is missing, start with one small action, because action comes before mood. Waiting until you feel like it keeps you stuck. Ten minutes on the task you keep postponing is already a step.
ADHD also shows up in relationships, and two habits help there. Before you share an opinion that might hurt, ask yourself whether it was asked for. And when someone tells you about a problem, you do not always have to solve it; often, listening is enough.
Where to go next
If these difficulties limit your work, studies or relationships, the next step is an assessment. You can read about it and book on the Adult ADHD service page, or go straight to the booking calendar. Appointments are in Trikala (Anni Komninis 1-3, 3rd floor, 42131) and online, and the practice serves Trikala, Karditsa, Kalampaka and online across Greece.
This article is general information. It does not replace a medical assessment.
Sources
Faraone SV, Banaschewski T, Coghill D, et al. The World Federation of ADHD International Consensus Statement: 208 evidence-based conclusions about the disorder. Neurosci Biobehav Rev 2021;128:789-818. https://doi.org/10.1016/j.neubiorev.2021.01.022
NHS. ADHD in adults (last reviewed 19 March 2025). https://www.nhs.uk/conditions/adhd-adults/
Song P, Zha M, Yang Q, et al. The prevalence of adult attention-deficit hyperactivity disorder: a global systematic review and meta-analysis. J Glob Health 2021;11:04009. https://doi.org/10.7189/jogh.11.04009
Faraone SV, Larsson H. Genetics of attention deficit hyperactivity disorder. Mol Psychiatry 2019;24(4):562-575. https://doi.org/10.1038/s41380-018-0070-0
NICE. Attention deficit hyperactivity disorder: diagnosis and management (NG87), amended September 2019. Copy on NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/books/NBK493361/
Adamou M, Arif M, Asherson P, et al. The adult ADHD assessment quality assurance standard (UKAAN AQAS). Front Psychiatry 2024;15:1380410. https://doi.org/10.3389/fpsyt.2024.1380410
Kooij JJS, Bijlenga D, Salerno L, et al. Updated European Consensus Statement on diagnosis and treatment of adult ADHD. Eur Psychiatry 2019;56:14-34. https://doi.org/10.1016/j.eurpsy.2018.11.001
