ADHD in adults -- ICD-11 diagnostic criteria

What ADHD is from the ICD-11 perspective

ADHD is the abbreviation of attention deficit hyperactivity disorder. In the eleventh revision of the International Classification of Diseases (ICD-11), developed by the World Health Organization, this disorder has the code 6A05 and belongs to the group of neurodevelopmental disorders, that is, conditions whose onset falls within the period of development and maturation of the nervous system.

The essence of ADHD is a persistent pattern of inattention as well as hyperactivity and impulsivity, which goes beyond what can be expected at a given stage of development and genuinely hinders day-to-day functioning. Inattention here means difficulty maintaining focus, organising tasks, and remembering obligations. Hyperactivity and impulsivity are excessive motor activity or inner restlessness and a tendency to act without thinking.

Placing ADHD among the neurodevelopmental disorders has an important consequence. It means that the symptoms do not appear suddenly in adulthood, but are present from childhood, although they were not always recognised at the time. An adult with ADHD did not acquire this disorder but lived with it earlier, often coping at the cost of considerable effort or with the support of those around them.

It is worth pointing out the limits of this text right away. The description of the criteria serves education and a better understanding of the disorder, but it does not replace clinical assessment. A diagnosis of ADHD is made by a qualified specialist after a full examination, not by reading an article or the result of an online test.

Why ADHD in adults often goes unnoticed

For many years, ADHD was treated almost exclusively as a problem of children, especially boys with marked hyperactivity. The result of this oversimplification is, today, a sizeable group of adults in whom the disorder was not recognised in childhood. Some of them, at school, were regarded as absent-minded, lazy, or disorganised, even though the source of the difficulties was a neurodevelopmental disorder.

Adulthood also changes the symptom picture. The visible, physical hyperactivity typical of a child often gives way, in an adult, to inner restlessness, a sense of tension, and difficulty relaxing. What usually comes to the fore are symptoms of inattention: chaos with obligations, putting off tasks, losing things and missing deadlines. Such difficulties are more readily attributed to character than to a disorder.

Many adults also develop compensatory strategies, that is, coping methods that mask the symptoms. These include, for example, to-do lists, reminders, working at the last minute under deadline pressure, or choosing highly varied occupations. These strategies can be effective until life's demands increase -- after changing jobs, the birth of a child, or the loss of an external daily structure.

For this reason, ADHD in adults is often recognised only when the existing coping methods cease to be sufficient. This does not mean the disorder arose at that moment. It only means it finally became visible. Sound ICD-11 diagnostics takes this history into account and reaches back to the period of childhood.

Diagnostic features of ADHD according to ICD-11

ICD-11 describes ADHD using diagnostic features, rather than a rigid list of points to be ticked off. The first and most important feature is a persistent pattern of inattention as well as hyperactivity and impulsivity. The word persistent is important here -- it refers to a lasting trait of functioning, not to temporary difficulties caused by stress, fatigue, or a difficult period of life.

The second feature is the onset of symptoms during the developmental period. The pattern of inattention or hyperactivity must already be present in childhood, typically in the early or middle school years. This requirement distinguishes ADHD from difficulties with concentration that appear only in adulthood and have other causes. In practice, the clinician takes a history regarding childhood and, where possible, uses information from the family or old school records.

The third feature is the presence of symptoms in more than one area of life. The difficulties must manifest in different situations -- for example, at work, at home, in study, and in relationships -- and not only in one specific context. If someone has problems with concentration exclusively in a single, exceptionally difficult situation, this does not meet that condition.

The fourth feature is a significant impact on functioning. The symptoms must cause genuine difficulties in the social, educational, or occupational sphere, or clear distress. The mere presence of features of inattention or restlessness is not sufficient -- many people are absent-minded or lively without having a disorder. Only the combination of a persistent pattern, early onset, presence in many areas, and genuine consequences makes up the picture of ADHD.

Symptoms of inattention in an adult

Inattention in ADHD is not ordinary absent-mindedness, but an established difficulty with directing and sustaining attention. In an adult, it manifests as being easily distracted and losing the thread during tasks, especially monotonous or unengaging ones. Work that requires longer focus is often put off or carried out in a rush at the last minute.

Difficulties with organisation and planning are also typical, sometimes described as deficits of executive functions. Executive functions are the mental abilities responsible for planning, starting and finishing tasks, setting their order, and managing time. Their weakening translates into a chaotic approach to obligations, unfinished projects, lateness, and a sense of constantly falling behind on matters.

The picture of inattention also includes forgetting obligations and losing objects such as documents, keys, or a phone. An adult with ADHD often describes having to use reminders and lists all the time, and yet something still slips by. Postponing tasks is also characteristic -- not from a lack of willingness, but because of difficulty starting them and keeping attention on them.

It is important to distinguish these symptoms from fatigue, overload, or low mood, which also weaken concentration. In ADHD, the difficulties with attention are lasting and reach back to childhood, whereas in other conditions they appear together with a specific problem and resolve along with it. This distinction is one of the tasks of differential diagnosis.

Symptoms of hyperactivity and impulsivity in adulthood

In children, hyperactivity usually takes the form of marked, visible motor restlessness -- running, climbing, an inability to sit still. In adulthood, this component often changes form. Instead of visible restlessness, there appears inner restlessness and tension, described as a sense of being constantly on the go, difficulty relaxing, or a need to be doing something without pause.

Some adults still feel an excess of motor energy, for example in the form of restless movements of the hands or legs, frequently standing up, or difficulty staying in one place for a longer time. Others redirect this restlessness into intense occupational or social activity, which is sometimes mistakenly perceived as merely a matter of temperament.

Impulsivity means acting without sufficient consideration of the consequences. In everyday life it manifests as interrupting others in conversation, difficulty waiting one's turn, hasty decisions, or sudden changes of plans. It may also show in financial decisions made on the spur of the moment or in a tendency towards risky behaviour.

Impulsivity in ADHD can be a source of genuine life difficulties -- in relationships, at work, and in managing everyday matters. It should not, however, be equated with a lack of responsibility or ill will. It is a symptom of a neurodevelopmental disorder, and recognising it makes it possible to better understand the source of the problems and to look for appropriate support.

Presentations of ADHD -- predominantly inattentive, hyperactive, or combined

ICD-11 makes it possible to specify the picture of ADHD by indicating which set of symptoms predominates. A predominantly inattentive presentation, a predominantly hyperactive-impulsive presentation, and a combined presentation are distinguished, the last being one in which both types of symptom occur with marked intensity at the same time.

In adults, the predominantly inattentive presentation is especially common. It can be harder to notice, because it is not associated with the visible hyperactivity that draws the attention of those around. A person with such a presentation may be regarded as dreamy, disorganised, or withdrawn, and their difficulties are often disregarded until they seriously affect work or study.

Specifying the predominant presentation is not merely a formality. It helps to better describe the individual patient and to adjust further management, because difficulties arising mainly from inattention and difficulties arising mainly from hyperactivity may require somewhat different support. The presentation may also change over the course of life -- the childhood picture is not always identical to the picture in adulthood.

Regardless of the presentation, the conditions for diagnosis remain the same. Each of them requires a persistent pattern of symptoms, onset in childhood, presence in many areas of life, and a significant impact on functioning. The presentation is a refinement of the picture, not a separate disorder.

The boundary between ADHD and normal absent-mindedness

Everyone is absent-minded at times, forgets matters, loses things, or has difficulty focusing on a boring task. The mere presence of such experiences is not evidence of ADHD. ICD-11 clearly requires that the symptoms be lasting, intensified beyond the level typical of a given stage of development, and that they cause genuine difficulties.

The boundary is marked out by three elements. The first is persistence -- in ADHD the difficulties are a constant trait of functioning from childhood, not a reaction to a specific difficult period. The second is scope -- the symptoms manifest in many areas of life, not only in one particularly demanding situation. The third is consequences -- the symptoms genuinely hinder functioning or cause clear distress.

The contemporary pace of life, the excess of stimuli, and multitasking mean that many people experience periodic difficulties with concentration. This is not, however, ADHD if the difficulties appeared only in adulthood, are linked to a specific overload, and resolve once it is reduced. ICD-11 diagnostics distinguishes a lasting neurodevelopmental disorder from the transient effects of lifestyle.

This distinction protects against two errors. On the one hand, against overdiagnosis -- attributing ADHD to every person who is sometimes absent-minded. On the other, against downplaying a genuine disorder in an adult whose difficulties have for years been explained solely as character traits. Both errors have genuine costs, which is why the assessment should be made by a specialist.

Differential diagnosis -- what resembles ADHD

Difficulties with concentration, restlessness, and impulsivity are not specific to ADHD alone. They also occur in other disorders, which is why an inseparable element of the diagnosis is differential diagnosis, that is, considering and ruling out alternative explanations of the clinical picture.

Reduced ability to focus accompanies mood disorders -- it appears in a depressive episode and also in bipolar type I disorder (code 6A60), where in the phase of elevated mood there is excessive activity and impulsivity that can easily be confused with hyperactivity. Here the course over time helps: ADHD is constant and reaches back to childhood, whereas symptoms in mood disorders appear in episodes.

Restlessness and difficulty with concentration also belong to the picture of anxiety disorders, and stress-related disorders as well as sleep problems weaken attention in themselves. In adults, an important role is also played by ruling out the influence of substances -- the symptoms may result from alcohol use (disorders due to alcohol use have code 6C40), the use of other psychoactive substances, or the effect of medication.

ADHD can also co-occur with other neurodevelopmental disorders, including autism spectrum disorder (code 6A02), which is likewise associated with difficulties in social functioning and the regulation of attention. ICD-11 permits more than one diagnosis in the same person if the picture requires it. Determining what is leading and what is co-occurring is a matter for the specialist after a full assessment.

The impact of ADHD on an adult's life

Unrecognised ADHD leaves its mark on many areas of an adult's life. At work it may mean unfinished tasks, lateness, difficulty meeting deadlines, and a sense of putting in a great deal of effort with disproportionate results. A frequent consequence is changes of jobs and a conviction of unrealised potential.

In relationships, difficulties with attention and impulsivity are sometimes perceived as a lack of interest, disregard, or irresponsibility. Repeated forgetting of arrangements, interrupting conversations, or hasty decisions can give rise to tensions, even though they do not stem from ill will. Understanding that a disorder lies behind these behaviours often changes the way loved ones interpret them.

A frequent, though indirect, effect of unrecognised ADHD is lowered self-esteem. For years a person hears that they are lazy, disorganised, or that they are not trying, and over time they take on this image of themselves. Accumulating failures and the effort put into making up for symptoms foster emotional difficulties, which is why adults with ADHD often have other mental health problems co-occurring.

A diagnosis is not a label, but a starting point. It makes it possible to understand the difficulties so far, to relieve oneself of an unjustified sense of guilt, and to purposefully choose methods of support -- from adjusting the work environment, through psychoeducation, to methods recommended by a specialist. A sound diagnosis changes the perspective from a judging one to an explaining one.

What the process of diagnosing ADHD in an adult looks like

A diagnosis of ADHD in an adult is made by a qualified specialist, most often a psychiatrist or a clinical psychologist, on the basis of a multi-element assessment. The foundation is a detailed history encompassing current difficulties and their history, with particular attention to the period of childhood, because ICD-11 requires an early onset of symptoms.

Valuable, though not always available, is information from people who knew the patient in childhood, as well as old documentation, for example school reports or assessments. These help to establish whether the pattern of inattention or hyperactivity was already present then, or whether the difficulties appeared only in adulthood, which would steer the diagnosis in a different direction.

Questionnaires and screening scales are also used in the assessment process. It must be remembered, however, what their role is -- they are supporting tools that indicate it is worth looking at the problem more closely, but they do not constitute a diagnosis. The result of a test, including an online test, does not replace clinical assessment. The aforementioned differential diagnosis is also part of sound ICD-11 diagnostics.

If you recognise the difficulties described here in yourself and they have persisted for a long time, are escalating, or are hindering everyday life, the appropriate step is to arrange a consultation with a specialist. Organising your own observations -- when the difficulties appeared, how long they have lasted, and how they affect your life -- helps the clinician and shortens the path to an accurate assessment.

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