Adaptive functioning: definition and clinical meaning
Adaptive functioning is the collection of learned conceptual, social, and practical skills a person uses to meet everyday demands, act on preferences, communicate, and participate in a community. In intellectual disability, adaptive functioning is one of the central diagnostic dimensions because it describes how a person applies skills in real environments. A complete assessment considers intellectual functioning, adaptive behavior, and developmental onset together, while recognizing individual strengths, cultural context, communication access, and available supports. AAIDD defining criteria; Tassé, Luckasson, and Schalock, 2016.
The three domains are conceptual skills, involving language, literacy, numbers, time, and self-direction; social skills, involving relationships, judgment, social responsibility, and safety; and practical skills, involving self-care, household activities, community mobility, employment routines, health management, and technology. These categories overlap in ordinary life. Organizing a medical appointment requires understanding information, communicating a choice, and navigating a practical routine. Assessment therefore examines patterns of functioning rather than interpreting a single task as proof of an entire person's capability. AAIDD adaptive behavior.
Adaptive skills are learned within a social and physical environment. A person may perform a familiar task independently, need a prompt in a new setting, or be unable to demonstrate a skill that has never been taught. The opportunities available to practice, the accessibility of information, and the expectations of peers in a comparable cultural context all affect observed performance. A report should explain what the person does, which conditions make the task possible, and what assistance is needed, while remaining faithful to standardized test scoring rules when a formal diagnosis is considered. AAIDD defining criteria.
Why the three-domain model matters
The conceptual, social, and practical organization reflects the multidimensional nature of adaptive behavior. Research in 388 children with and without intellectual disability found that a three-correlated-factor model fit the data better than the tested single-factor model. A 2026 study of the Diagnostic Adaptive Behavior Scale also supported the tripartite structure. These findings justify examining domains separately while acknowledging that they are correlated and that particular activities combine them. Psychometric support for the model in a studied sample does not automatically establish equal measurement performance in every language and population. Arias et al., 201370019-X); Tassé et al., 2026.
A domain-based formulation is more useful than a global judgment such as 'cannot function independently.' It can establish that a person reads a familiar schedule, enjoys and sustains friendships, recognizes when assistance is needed, and requires extensive help with financial transactions. Each statement suggests a different assessment question and a distinct support response. Functional profiles vary because development, communication, health, instruction, social experience, and environmental accessibility vary. AAIDD adaptive behavior.
Conceptual adaptive skills
Functional language and understanding
Conceptual skills encompass the interpretation and communication of information relevant to daily living. In childhood, these may involve responding to familiar requests, recognizing pictures, understanding sequences, learning vocabulary, and using symbolic communication. At school age, expectations expand to functional reading, interpreting schedules, following multistep directions, and organizing learned information. In adulthood, conceptual demands can include understanding a bill, comparing service options, keeping track of appointments, and recognizing the consequences of a decision. These are meaningful tasks because they require applying knowledge beyond a test exercise. AAIDD adaptive behavior.
Communication access changes what can be observed. A person who uses gestures, picture symbols, signed language, assistive typing, or a speech-generating device may communicate preferences and demonstrate comprehension more effectively with these supports than through a standard spoken interview. Hearing loss, speech-motor difficulty, limited proficiency in the test language, and unfamiliar abstract expressions can also constrain responses. Clinicians coordinate assessment with speech-language professionals and examine receptive and expressive abilities in accessible forms. ASHA intellectual disability practice portal.
Number, time, and money concepts
Numbers and time become adaptive skills when they help someone manage actual circumstances. Recognizing that an appointment is tomorrow, understanding the sequence of a bus journey, comparing quantities, using a timer, or calculating a basic purchase are different examples of conceptual functioning. A person may identify currency denominations but need assistance identifying an unexpected electronic payment, interpreting a service contract, or noticing an unrealistic financial offer. The assessment must specify the demand and document whether a calculator, clear interface, or trusted support makes participation possible. AAIDD adaptive behavior.
Self-direction and judgment
Self-direction concerns recognizing preferences, initiating activities, organizing steps, responding to feedback, and deciding when to ask for help. These skills intersect with memory, communication, and the ability to predict consequences. A person may independently choose a meal yet request help navigating unfamiliar payment systems. Such a profile calls for supported implementation of a decision, with the person's preferences preserved. The inability to perform every procedural step should never be assumed to erase the person's perspective or participation in the decision. AAIDD defining criteria.
Social adaptive skills
Relationships and reciprocal communication
Social adaptive functioning covers participation in interpersonal exchanges, understanding others' messages, maintaining relationships, managing disagreements, and communicating boundaries. Young children may demonstrate developing social ability through joint play, turn taking, asking for help, and understanding familiar social expectations. Adolescents and adults face increasingly complex demands involving friendship, workplace interaction, privacy, and intimate relationships. The assessment should describe actual goals and interactions rather than defining social competence solely through politeness, conformity, or eye contact. AAIDD adaptive behavior.
Social understanding, safety, and exploitation
The social domain includes judgment about trustworthiness, gullibility, recognizing manipulation, understanding ordinary rules, and avoiding victimization. AAIDD explicitly includes these features because social vulnerability may emerge even in someone who is sociable, articulate, and motivated to connect. Accessible education can address recognizing warning signs, keeping personal information private, seeking a second opinion, declining unwanted contact, and identifying people who can help. Social safety also depends on the behavior of others, organizational procedures, and effective protection from abuse. AAIDD adaptive behavior; AAIDD DABS.
An assessor should never confuse vulnerability produced by coercion or unequal power with a person's supposed responsibility for being exploited. Meaningful support includes accessible consent information, routes to report concerns, respect for refusal, and reliable safeguarding arrangements. The clinical description can identify which interpersonal information is difficult to interpret without treating the person as globally incapable of friendship, intimacy, employment, or community life. NICE NG11.
Social differences and associated conditions
Intellectual disability can coexist with autism, language disorders, anxiety, trauma-related difficulties, sensory impairments, and other conditions affecting social situations. These different mechanisms require their own clinical assessment. Autism-specific diagnostic characteristics must not be inferred from an adaptive behavior rating, and social difficulties alone do not establish intellectual disability. The separate encyclopedia article Autism and Intellectual Disability in Adults: Differences and Support examines that differential question. ASHA intellectual disability practice portal.
Practical adaptive skills
Personal care and domestic routines
Practical skills include eating, dressing, personal hygiene, preparing food, organizing belongings, cleaning, laundry, and using household equipment safely. Independence in these activities has to be judged in relation to developmental stage and actual context. A young child normally relies on substantial care; an adult with limited hand mobility may know and direct a task while requiring physical assistance. Clinical notes should distinguish understanding, initiating, executing, and checking the results of an activity. These distinctions enable relevant accommodations rather than broad judgments about competence. AAIDD adaptive behavior.
Health, medication, and safety
Managing health care may involve describing symptoms, recognizing a change in wellbeing, scheduling an appointment, understanding medical instructions, and following a medication routine. These are combined conceptual, social, and practical tasks. A plain-language care plan, picture instructions, alarms, adapted containers, and reliable assistance can enable greater involvement in treatment. An unexpected deterioration in familiar practical skills warrants investigation of illness, pain, medication effects, fatigue, depression, sensory change, or other factors rather than immediate attribution to the developmental condition. NICE NG11.
Community participation, transportation, work, and digital life
Travel planning, recognizing common hazards, using transport, shopping, following work routines, handling technology, and communicating with service providers are common practical demands. The digital environment alters these demands continually. A person may confidently telephone a family member but have difficulty with an unfamiliar account-verification interface, complex online banking, or an unannounced transportation-app change. Adaptive assessment should consider whether interfaces are understandable, whether instruction has been available, and whether the person can use accessible alternatives. AAIDD DABS.
Employment status is an especially poor shortcut for interpreting practical competence. A person may learn consistent workplace routines when tasks are demonstrated, schedules are predictable, and communication is accessible, but encounter exclusion in an unaccommodating workplace. Functional planning therefore identifies particular tasks and barriers, job coaching or adaptations when appropriate, and the person's own occupational goals. Test results can contribute to such planning without determining someone's vocational future. AAIDD defining criteria.
Adaptive functioning and intellectual functioning are distinct
Intellectual functioning broadly concerns learning, reasoning, and problem-solving. Adaptive functioning concerns the skills actually used to meet environmental demands. Both are required in an intellectual disability diagnostic formulation, and they should be assessed separately before being integrated. A theoretical or statistical relationship does not permit one score to stand in for the other. Tassé, Luckasson, and Schalock describe a strong correlation without a simple causal equivalence and emphasize considering both forms of evidence jointly. Tassé, Luckasson, and Schalock, 2016.
A person with a low measured IQ may demonstrate important practical strengths; another person may show relatively strong vocabulary but limited social judgment or everyday financial skills. Neither observation alone establishes or excludes an intellectual disability. A valid assessment also addresses developmental history, measurement error, communication, and relevant health or environmental circumstances. General psychometric interpretation is examined separately in IQ: What Intelligence Quotient Measures and What It Means. AAIDD FAQs.
Role in the diagnosis of intellectual disability
AAIDD criteria and clinical interpretation
AAIDD defines intellectual disability through significant limitations in both intellectual functioning and adaptive behavior, with onset before age 22. In its current framework, significant adaptive limitations may be indicated by a standardized score approximately two or more standard deviations below the mean in at least one conceptual, social, or practical domain, using an appropriately selected measure. Clinicians interpret the score alongside test reliability, normative relevance, developmental information, and other evidence. An isolated questionnaire score does not establish a diagnosis. AAIDD FAQs.
DSM-5-TR and ICD-11
DSM-5-TR describes intellectual developmental disorder with deficits in intellectual and adaptive functioning beginning during development, and functional adaptation is central to severity judgments. ICD-11 uses the disorders-of-intellectual-development classification and integrates intellectual and adaptive evidence. The 2024 WHO Clinical Descriptions and Diagnostic Requirements provide additional practical clinical guidance. Differences in nomenclature and operational procedures mean clinicians should identify which system is being used instead of treating every threshold or severity statement as interchangeable. WHO ICD-11 clinical requirements; Tassé et al., 2026.
Developmental onset is crucial. If someone develops significant everyday-functioning difficulties after previously typical development, acquired medical, neurological, psychiatric, or environmental explanations require examination. Global developmental delay in early childhood is an age-related clinical concept and should be assessed through age-appropriate multidisciplinary methods. The diagnostic process establishes the condition; support planning additionally determines what arrangements improve the person's everyday participation. AAIDD defining criteria.
Standardized adaptive behavior assessment
DABS, Vineland-3, and ABAS-3
The Diagnostic Adaptive Behavior Scale (DABS) is a norm-referenced interview measure designed for ages 4 through 21. Its conceptual, social, and practical domains are explicitly aligned with the diagnostic adaptive behavior framework, including items relevant to classifying limitations near the diagnostic threshold. Vineland-3 organizes its content into communication, daily living, socialization, and motor domains, with interviews and rating formats. ABAS-3 measures adaptive behavior using conceptual, social, and practical domains. The tools differ in age coverage, item content, format, scores, and normative foundations; each should be chosen for the specific clinical question. AAIDD DABS; Pearson assessment overview.
What psychometric evidence demonstrates
A DABS validity study reported correlations with Vineland-II ranging from 0.70 to 0.84, with test–retest coefficients between 0.78 and 0.95 and more variable agreement between different respondents. A 2026 factor-analysis study supported the three-domain model and reported strong internal consistency within its sample. These results support the instrument's use under appropriate conditions; they cannot by themselves verify a newly translated version, an unstudied cultural population, or a diagnosis made by an unqualified assessor. Published psychometric estimates must be connected to the particular test form, norms, and intended population. Tassé et al., 2016, DABS validity; Tassé et al., 2026.
Reports from the person and knowledgeable informants
Parents, teachers, partners, residential staff, and colleagues may observe different parts of the person's life. A respondent who has rarely seen independent travel may reasonably report unfamiliarity, while another can describe competent performance on an established route. Differences between informants are informative when connected to opportunities and contexts. The evaluator should seek direct input from the person, identify the setting and reference period, document uncertainty, and use observation or records when these clarify conflicting reports. A numerical average of contradictory accounts cannot replace this investigation. ASHA intellectual disability practice portal; Tassé et al., 2012.
Capacity, typical performance, and support
A person may demonstrate a task after explicit instruction but rarely perform it without a reminder. Such observations concern different questions: potential performance in an optimized setting and typical performance in everyday life. Adaptive rating instruments have their own rules for the dimension being scored; clinicians should follow their manuals and then supplement standardized results with direct functional information. A report is more useful when it describes what can be done without support, with reminders or visual prompts, with physical assistance, and with other accommodations, while avoiding an invented composite score from these observations. AAIDD defining criteria.
Cultural and linguistic fairness
Adaptive performance is understood in relation to peers in the individual's community and culture. Independent living, financial arrangements, household division of labor, interpersonal formality, and social responsibilities vary across settings. Someone who lives with family and shares household decisions may be participating in a common cultural arrangement. The test must distinguish the demands actually encountered from stereotypes about what people of a given age should do. AAIDD defining criteria.
Multilingual and culturally responsive assessment considers all languages used by the person, communication preferences, prior educational exposure, and the validity of available norms. Literal translation of a scale does not guarantee equivalent item difficulty or measurement properties. Sensory and motor differences may require accessible test procedures. Clinicians should report which accommodations were used, what the standardized score validly represents, and which questions remain unresolved. ASHA intellectual disability practice portal.
Opportunity deprivation can produce functional gaps. If a person has never been allowed to use a kitchen, plan travel, handle money, or communicate an independent preference, an inability to perform that task reflects both current limitations and their learning history. In a clinically warranted evaluation, this does not invalidate genuine adaptive limitations, but it changes their interpretation and informs what should happen next. Carefully structured opportunities to learn and reassessment after instruction can help describe the person's developmental possibilities. AAIDD defining criteria.
Support needs and severity
Adaptive functioning describes learned functional performance, while support needs describe the resources required for participation under particular conditions. Support needs can be influenced by hearing, mobility, health, environmental accessibility, communication tools, household circumstances, and the availability of trusted relationships. People with similar adaptive scores can therefore require different services and obtain different outcomes from the same program. AAIDD defining criteria.
Diagnostic severity reflects the extent of relevant functional limitations within an accepted classification. A person-centered support plan asks additional questions: what matters to the person, which daily tasks are meaningful, how they currently perform, and what reliable assistance enables their choices. A communication device may make medical participation possible; accessible transportation may support employment; a visual routine may increase control over daily activities. The continued presence of support can be entirely compatible with growing autonomy. WHO ICD-11 clinical requirements; NICE NG11.
Evidence-based instruction and everyday skill development
Selecting meaningful goals
Adaptive learning begins with a goal that the person values and that corresponds to an ordinary context. A precise target might be preparing a favorite snack safely, using an accessible telephone to contact a friend, or learning a predictable journey to an activity. The support team identifies baseline performance, potential hazards, the sequence of task steps, and the communication and environmental adjustments needed. Progress should be evaluated through meaningful participation and generalization rather than mere completion of a classroom exercise. NICE NG11.
Task analysis, prompting, and reinforcement
Instructional programs may divide a task into teachable steps, demonstrate each step, offer visual or verbal prompts, arrange repeated practice, and use appropriate feedback. Prompting can be changed as proficiency develops. Learners may benefit from consistent schedules, choice-making opportunities, adapted materials, and coaching for family members or staff. The effectiveness of such packages depends on the skill, learner, setting, teaching consistency, and outcome measure. The intervention should respect preferences and preserve a person's ability to decline unwanted activities. Liu et al., 2025 systematic review.
Findings from systematic reviews
A systematic review of caregiver-implemented daily living skills instruction identified 38 articles. Twenty studies, containing 21 experiments, met specified high-quality single-case design criteria; most of those experiments reported improvements in targeted tasks. Common strategies included caregiver training, prompts, reinforcement, and task analysis. The conclusion concerns studied daily living skills in a mixed developmental-disability population. It does not show that every participant gains the same degree of independence or that all effects persist without suitable instruction and support. Liu et al., 2025.
A 2024 systematic literature review of video prompting for people with severe disabilities reported favorable skill-learning findings, often in daily living and vocational tasks. Many interventions combined video prompts with other methods, and small studies limited broad comparisons. Technology-assisted instruction may help particular learners when it is accessible, preferred, and evaluated for its real-world effects. Evidence for acquiring a trained sequence is stronger than generalized claims about lifelong independent living, employment, or quality of life. Video prompting review, 2024.
Generalization, choice, and support evaluation
A useful outcome measure asks whether the skill occurs in a familiar home, school, or workplace setting, whether it survives a change of instructor, whether the person can use it after a delay, and whether it serves a chosen purpose. Support plans can record accurate task completion, level of prompting, requests for help, safety, satisfaction, and participation. Excessive dependence on a single supporter or distress during training should prompt revision. Instructional success and improvements in quality of life are related but separate outcomes that require their own evidence. NICE NG11.
Lifespan perspectives
In early childhood, assessment focuses on communication, emerging routines, interaction, play, and everyday care in age-appropriate contexts. Children's performance varies with family routines and developing opportunities. School-age assessment adds functional literacy, social understanding, increasing responsibility, and participation in educational and community settings. Adaptive skill expectations should reflect developmental and cultural context while safeguarding access to early intervention where needs are apparent. ASHA intellectual disability practice portal.
In adolescence, new demands often concern transportation, peer relationships, digital privacy, workplace preparation, and the use of community resources. The aim of assessment is to understand the skills and supports that enable an increasingly chosen adult life. Plans are strongest when young people participate in setting goals and receive real opportunities to practice them. Transition needs may involve several systems, including education, health services, employment support, and housing. AAIDD adaptive behavior.
Adults continue learning and adapting to changes in home, work, relationships, health, and technology. An established intellectual disability does not mean adaptive functioning is static. New skills can develop through practice and accessibility; changing health can also affect familiar performance. A sudden or progressive decline warrants examination of illness, pain, medication effects, psychological problems, sensory change, or neurological disease. Maintaining an individual baseline is valuable for recognizing new needs. NICE NG11.
Mental health, behavior, and underlying causes
Some changes in adaptive performance occur because of anxiety, depression, physical illness, trauma, distress, environmental disruption, or inaccessible communication. What appears as refusal or disruptive behavior can be an attempt to escape pain, express a need, or respond to an overwhelming demand. NICE guidance recommends assessing communication, medical and mental-health factors, relationships, sensory conditions, and the environments in which the behavior occurs. Functional analysis can inform supportive changes and skill teaching when behavior presents a concern. NICE NG11.
This distinction is clinically important because a decline in adaptive behavior should not automatically be ascribed to a person's longstanding developmental condition. A complete assessment takes the reported change seriously and can involve medical, psychiatric, psychological, and communication specialists as needed. Immediate concerns about self-injury, abuse, acute illness, or personal safety require professional evaluation and locally appropriate safeguarding or emergency services. The clinical objective remains the person's health, safety, participation, and preferred quality of life. NICE NG11.
Interpreting the strength and limits of the science
Established clinical evidence identifies adaptive behavior as an indispensable component of intellectual disability diagnosis, supports the three-domain conceptual model, and requires assessment within developmental and cultural context. Instrument studies offer evidence about reliability and validity for tested versions and groups. Formal clinical guidelines support accessible communication and individualized environmental adaptations. These sources establish important standards for evaluation without eliminating the need to assess an individual directly. AAIDD FAQs; Tassé et al., 2026.
Intervention evidence is more specific. Task-focused experimental studies and systematic reviews support selected instructional procedures, particularly for trained daily living tasks, but programs differ in participant characteristics, instructional components, settings, and outcome measures. Larger comparative trials, long-term follow-up, culturally diverse research, and more direct measurement of participant-defined quality of life remain important scientific needs. It would overstate existing evidence to rank one universal technique as best for everyone or assume that performance during instruction guarantees lasting community independence. Liu et al., 2025; Tassé et al., 2016, DABS validity.
Common questions about adaptive functioning
Does IQ determine adaptive functioning?
IQ and adaptive functioning are related but distinguishable. Standardized intellectual testing cannot substitute for evidence of everyday conceptual, social, and practical behavior. A clinical assessment considers both and integrates them with developmental history and professional judgment. Tassé, Luckasson, and Schalock, 2016.
Can someone have strong social skills but limited practical skills?
Yes. Adaptive profiles can differ across domains and individual activities. A person may manage friendships competently while requiring assistance with unfamiliar transportation or finances. Each area deserves its own description and support plan. AAIDD adaptive behavior.
Is using assistance evidence of an inability to choose?
Assistance and self-determination address different dimensions. A person can make a decision, communicate a preference, and direct supporters while receiving help with motor tasks, reading, technology, or transportation. Evaluation should identify the person's participation accurately. AAIDD defining criteria.
Can adaptive functioning improve in adulthood?
Yes. Adults can develop new routines, communication strategies, and community skills through instruction, accessible environments, practice, and sustained support. The extent and pace of change vary, and specific interventions require ongoing evaluation. Liu et al., 2025.
Is a single questionnaire sufficient to diagnose intellectual disability?
A questionnaire can contribute essential information, but clinical diagnosis requires evidence concerning intellectual functioning, adaptive behavior, developmental onset, and relevant contextual and measurement factors. Qualified professional evaluation is necessary when diagnostic decisions affect care and services. AAIDD FAQs.
Conclusion
Adaptive functioning links developmental diagnosis to the actual conditions of everyday life. Conceptual skills support understanding and self-direction, social skills support relationships and judgment, and practical skills support the activities through which a person participates in home, education, work, health care, and community settings. Scientific assessment describes these domains precisely, interprets them in cultural and developmental context, and connects findings to accessible instruction and the supports the person chooses. The most useful result is a clearer basis for learning, autonomy, wellbeing, safety, and meaningful participation.
Related Articles
Autism and Intellectual Disability in Adults: Differences and Support — Differential understanding of co-occurring developmental conditions in adult life.
IQ: What Intelligence Quotient Measures and What It Means — General intelligence measurement and psychometric interpretation.
Levels of Intellectual Disability: Mild, Moderate, Severe, and Profound — Severity framework organized by adaptive functioning and practical support needs.
Causes of Intellectual Disability: Genetic, Prenatal, and Developmental Factors — Etiologic categories and limits of causal attribution.
References
American Association on Intellectual and Developmental Disabilities. (2017). Diagnostic Adaptive Behavior Scale. AAIDD.
American Association on Intellectual and Developmental Disabilities. (2021–2026). Adaptive behavior. AAIDD.
American Association on Intellectual and Developmental Disabilities. (2021–2026). Defining criteria for intellectual disability. AAIDD.
American Association on Intellectual and Developmental Disabilities. (2021–2026). FAQs on intellectual disability. AAIDD.
American Speech-Language-Hearing Association. (n.d.). Intellectual disability: Practice portal. ASHA.
Arias, B., Verdugo, M. Á., Navas, P., and Gómez, L. E. (2013). Factor structure of the construct of adaptive behavior in children with and without intellectual disability. International Journal of Clinical and Health Psychology, 13(2), 155–166. https://doi.org/10.1016/S1697-2600(13)70019-X70019-X).
Liu, R., Gerow, S., Lory, C., McGinnis, K., and Cosottile, D. (2025). Caregiver-implemented interventions to improve daily living skills for individuals with developmental disabilities: A systematic review. Behavior Modification. https://doi.org/10.1177/01454455241296514.
National Institute for Health and Care Excellence. (2015). Challenging behaviour and learning disabilities: Prevention and interventions (NG11). https://www.nice.org.uk/guidance/ng11/chapter/recommendations.
Pearson. (n.d.). ABAS-3 and Vineland-3: Assessment overview.
Tassé, M. J., Luckasson, R., and Schalock, R. L. (2016). The relation between intellectual functioning and adaptive behavior in the diagnosis of intellectual disability. Intellectual and Developmental Disabilities, 54(6), 381–390. https://doi.org/10.1352/1934-9556-54.6.381.
Tassé, M. J., Schalock, R. L., Balboni, G., Spreat, S., and Navas, P. (2016). Validity and reliability of the Diagnostic Adaptive Behaviour Scale. Journal of Intellectual Disability Research, 60(1), 80–88. https://doi.org/10.1111/jir.12239.
Tassé, M. J., Schalock, R. L., Navas, P., Andridge, R., and Balboni, G. (2026). Confirming the tripartite factor structure of the Diagnostic Adaptive Behavior Scale. American Journal on Intellectual and Developmental Disabilities, 131(4), 304–313. https://doi.org/10.1080/19447515.2026.2669462.
Tassé, M. J., and colleagues. (2012). The construct of adaptive behavior: Its conceptualization, measurement, and use in the field of intellectual disability. https://pubmed.ncbi.nlm.nih.gov/22809075/.
Utilizing video prompting with people with severe disabilities: A systematic literature review. (2024). Children and Youth Services Review, 161, 107652. https://doi.org/10.1016/j.childyouth.2024.107652.
World Health Organization. (2024). Clinical descriptions and diagnostic requirements for ICD-11 mental, behavioural and neurodevelopmental disorders. https://www.who.int/publications/i/item/9789240077263.