How to Code Intellectual Developmental Disorders in ICD-11: Complete Guide

Introduction

Intellectual developmental disorders (IDD) represent a heterogeneous group of conditions characterized by significant limitations in both intellectual functioning and adaptive behavior, with onset during the developmental period. These conditions affect approximately 1% to 3% of the world population, constituting one of the most frequent causes of need for educational, social, and medical support throughout life. Intellectual functioning refers to general mental abilities, including reasoning, problem-solving, planning, abstract thinking, comprehension of complex ideas, and learning. Adaptive behavior, in turn, encompasses conceptual, social, and practical skills necessary for functioning in everyday life.

Precise coding of intellectual developmental disorders in ICD-11 is essential for multiple purposes. From an epidemiological perspective, it allows tracking of the prevalence, incidence, and distribution of these disorders in different populations and geographic contexts, providing the foundation for public health, education, and social assistance policies. From a clinical perspective, appropriate coding facilitates communication among professionals from different specialties involved in multidisciplinary care of these individuals, including physicians, psychologists, speech-language pathologists, occupational therapists, and educators. Administratively, it ensures appropriate reimbursement by health systems and insurers for extensive neuropsychological evaluations, specialized therapies, and habilitation and rehabilitation programs that are frequently necessary.

The impact of correct coding extends beyond medical and administrative aspects. Precise classification is fundamental for access to social rights, social security benefits, specialized educational programs, and community support services. Furthermore, appropriate specification of the severity level through ICD-11 subcategories allows for individualized support planning, aligning resources and interventions to the actual needs of each person. Careful documentation also enables research on intervention effectiveness, development of new therapeutic approaches, and better understanding of etiological factors, contributing to continuous advances in the field.

Correct ICD-11 Code

Code: 6A00

Description: Intellectual developmental disorders

Chapter: 06 - Mental, behavioral and neurodevelopmental disorders

Official definition (ICD-11):

Intellectual developmental disorders are a group of conditions, of diverse etiology, that originate during the developmental period, characterized by intellectual functioning and adaptive behavior significantly below average, which are approximately two or more standard deviations below the mean (approximately less than the 2.3rd percentile), based on standardized tests, adequately normed, administered individually. Where adequately normed and standardized tests are not available, the diagnosis of intellectual developmental disorders depends more on clinical judgment based on adequate assessment of equivalent behavioral indicators.

Coding notes:

Use an additional code, if desired, to identify any known etiology (for example, specific genetic syndrome, prenatal alcohol exposure, perinatal anoxia).

When to Use This Code

✅ Situation 1: Child with global developmental delay identified in school screening

Criteria:

• Age 6-18 years with persistent academic difficulties
• Intellectual functioning significantly below average (IQ < 70)
• Limitations in adaptive behavior in at least two domains
• Onset during developmental period (before age 18)
• Exclusion of other causes (hearing impairment, visual impairment, severe neglect)

Example: "9-year-old boy referred by school for severe learning difficulties. Neuropsychological evaluation reveals total IQ of 62 (WISC-V), with deficits in all cognitive areas. Vineland Scale shows equivalent age of 5 years in communication skills, 4 years in daily living skills, and 5 years in socialization. Parents report he has always been slower than siblings in acquiring developmental milestones. Gestational and perinatal history without complications. Neurological examination and neuroimaging normal. Karyotype and genetic panel for intellectual disability in progress. Code 6A00.1 applied (Intellectual developmental disorder, mild), multidisciplinary follow-up scheduled and referral for special education."

✅ Situation 2: Adult with functional limitations since childhood seeking social benefit

Criteria:

• Adult (>18 years) with history of difficulties since childhood
• Persistent limitations in adaptive functioning
• Need for continuous support in activities of daily living
• Assessment documenting borderline or below intellectual functioning

Example: "25-year-old man presents for expert evaluation aiming for continuous cash benefit (BPC). Mother reports he was never able to follow regular schooling, having attended only up to 4th grade in special school. Currently unemployed, requires supervision for financial management and public transportation. Lives with parents who assist with all complex activities. Current evaluation with WAIS-IV shows total IQ of 58. Adaptive behavior scale shows functioning equivalent to 10-12 years in autonomy and social skills. Code 6A00.1 applied, detailed report prepared for social security purposes and supervised occupational activities recommended."

✅ Situation 3: Infant with genetic syndrome and developmental delay

Criteria:

• Infant or young child (<3 years) with known genetic syndrome
• Significant delays in motor and cognitive developmental milestones
• Developmental assessment showing functioning below 2 standard deviations
• Prognosis of persistent intellectual limitations

Example: "18-month-old infant with Down syndrome (trisomy 21 confirmed by karyotype). Evaluation by Bayley-III test shows cognitive index of 60, language of 55, and fine motor of 65. Does not sit without support, does not produce words, presents hypotonia. Regular follow-up with geneticist, pediatric neurologist, and early intervention team. Code 6A00 applied (generic, as too young to specify definitive severity) combined with code for trisomy 21. Family receives guidance on early stimulation, physical therapy, and speech therapy. Annual reassessment scheduled to determine severity level as development progresses."

✅ Situation 4: Adolescent with moderate intellectual disability in transition to adulthood

Criteria:

• Adolescent (14-18 years) with established diagnosis of IDD
• Planning transition to adult services
• Need to define support level for adult life
• Reassessment to update functional profile

Example: "16-year-old adolescent with previous diagnosis of intellectual disability since age 7. Current reassessment for transition planning shows total IQ of 45 (WISC-V). Adaptive functioning compatible with 7-8 years. Can perform simple household tasks with supervision, but requires support for complete personal hygiene, money management, and community navigation. Attends special school with good performance in practical activities. Code 6A00.2 applied (Intellectual developmental disorder, moderate). Transition plan developed including protected vocational workshops, continuation of therapies, and family preparation for guardianship/conservatorship upon reaching adulthood."

✅ Situation 5: Child with known etiology (fetal alcohol syndrome)

Criteria:

• Child with documented history of prenatal alcohol exposure
• Typical facial and physical characteristics of FAS
• Significant intellectual and adaptive deficits
• Need for dual coding (IDD + etiology)

Example: "7-year-old girl in institutional care since age 2. Medical record documents heavy alcohol use by biological mother during pregnancy. Physical examination shows characteristic facies (short nasal filtrum, thin upper lip, narrow palpebral fissures), microcephaly, short stature. Neuropsychological evaluation reveals IQ of 55, with more pronounced deficits in executive functions and memory. Adaptive behavior severely compromised, with equivalent age of 3-4 years. Skull MRI shows corpus callosum hypoplasia. Codes 6A00.1 (mild IDD) and additional code for fetal alcohol syndrome applied. Multidisciplinary follow-up with psychology, speech-language pathology, and occupational therapy."

✅ Situation 6: Differential evaluation between IDD and specific learning disorder

Criteria:

• Child with school difficulties requiring differential diagnosis
• Comprehensive assessment of intelligence and academic abilities
• Analysis of discrepancy between IQ and academic performance
• Adaptive behavior assessment for differentiation

Example: "10-year-old boy referred for difficulties in reading and mathematics. Evaluation with WISC-V shows verbal IQ of 68, performance of 72, total IQ of 67. Academic achievement tests show reading and mathematics equivalent to 2nd grade (expected: 5th grade). Importantly: Vineland Scale reveals adaptive behavior also significantly below expected (equivalent to 6-7 years), with difficulties in all areas of daily living, not just academics. Code 6A00.1 applied (not isolated specific learning disorder, but IDD, as there is global impairment of adaptive functioning). Referred for special education and therapies."

✅ Situation 7: Institutionalized adult with severe IDD requiring diagnostic update

Criteria:

• Adult in long-term care facility
• Severe IDD with need for extensive support
• Severe limitations in communication and self-care
• Update for care planning purposes

Example: "35-year-old man institutionalized since age 15. Does not verbalize, communicates through basic gestures. Totally dependent for hygiene, feeding, and all activities of daily living. Also presents controlled epilepsy and occasional self-injurious behaviors. Adapted evaluation (observational scales due to inability for formal testing) estimates cognitive functioning < 25 and global developmental age of 1-2 years. Code 6A00.4 applied (Profound IDD) and additional codes for epilepsy and challenging behaviors. Care plan emphasizes quality of life, seizure control, positive behavioral management, and continuous caregiver team training."

When NOT to Use This Code

❌ Situation 1: Specific learning difficulties without global adaptive impairment

If child presents difficulties ONLY in reading, writing, or mathematics, but functions adequately in other areas of life → use codes for specific learning disorders (6A03)

Rationale: IDD requires GLOBAL impairment of adaptive functioning, not just isolated academic difficulties.

❌ Situation 2: Dementia or cognitive decline acquired in adulthood

If adult develops cognitive deficits after a period of normal functioning → use codes for dementia or neurocognitive disorders (chapter on neurological diseases)

Rationale: IDD by definition has ONSET during the developmental period (before age 18).

❌ Situation 3: Borderline intellectual functioning without adaptive impairment

If IQ between 70-84 (borderline) but adaptive behavior PRESERVED → do not use IDD code

Rationale: IDD diagnosis requires BOTH: intellectual functioning AND adaptive behavior significantly below average.

❌ Situation 4: Autism spectrum disorder with preserved intelligence

If child with ASD presents normal IQ but social limitations → use only ASD code (6A02), not 6A00

Rationale: Limitations in ASD are primarily social/communicative; if IQ is normal, there is no concomitant IDD.

❌ Situation 5: Severe environmental deprivation with reversible delays

If child in situation of severe neglect presents delays that REVERSE with stimulation → do not code as permanent IDD

Rationale: IDD implies a PERSISTENT condition; purely environmental delays may be transitory.

Step-by-Step Coding Process

Step 1: Initial Assessment

Confirm the presence of essential criteria to consider an IDD diagnosis:

1. Onset during development: Symptoms started before age 18
2. Intellectual deficits: Intellectual functioning significantly below average
3. Adaptive deficits: Limitations in adaptive behavior in at least 2 domains
4. Functional impact: Need for some level of support

Practical example: An 8-year-old child with persistent school difficulties, developmental milestone delays since early childhood, requiring help with tasks that peers perform independently. These elements indicate the need for formal evaluation for possible IDD.

Step 2: Verification of Diagnostic Criteria

Perform comprehensive assessment including:

• Intellectual functioning testing: WISC-V, WAIS-IV, Stanford-Binet or similar
• Adaptive behavior assessment: Vineland-3, ABAS-3 or equivalent
• Developmental history: Motor, language, social, self-care milestones
• Physical and neurological examination: Rule out treatable causes
• Etiological investigation: Karyotype, microarray, neuroimaging when indicated

Practical example: WISC-V administration reveals total IQ of 58 (< 2 standard deviations). Vineland shows communication at 0.5th percentile, daily living at 1st percentile, socialization at 0.8th percentile. History confirms delays since age 2. These findings meet criteria for IDD.

Step 3: Exclusion of Differential Diagnoses

Systematically evaluate conditions that may mimic or coexist with IDD:

• Sensory impairments: Audiometry, ophthalmological evaluation
• Autism spectrum disorder: ADOS-2, ADI-R or specialized clinical evaluation
• Specific learning disorders: Assess whether deficits are global or specific
• Environmental deprivation: Detailed social history
• Treatable medical conditions: Congenital hypothyroidism, phenylketonuria, etc.

Practical example: Audiometry and ophthalmological evaluation normal, ruling out primary sensory deficits. Evaluation for ASD negative (social interaction appropriate to developmental level, without stereotypies or restricted interests). Stable family history rules out severe deprivation. Normal neonatal metabolic screening.

Step 4: Determination of Specificity Level (Severity)

Decide the severity level based primarily on adaptive behavior:

• 6A00.0 (Mild): IQ 50-69; can achieve independence in self-care and practical life skills in adulthood; generally acquires academic skills through 6th grade; can work with minimal support
• 6A00.1 (Moderate): IQ 35-49; can learn basic self-care and simple social skills; limited academic skills (through 2nd-3rd grade); requires moderate support in adulthood; can participate in sheltered workshops
• 6A00.2 (Severe): IQ 20-34; limited vocabulary, comprehension of simple commands; self-care with substantial assistance; does not master academic skills; requires continuous supervision
• 6A00.3 (Profound): IQ < 20; nonverbal or very limited communication; total or near-total dependence; generally significant motor and sensory comorbidities

Practical example: IQ of 58, adaptive behavior equivalent to 60% of chronological age, able to perform simple household tasks with guidance, reads and writes at basic level, requires support for financial management and complex decisions → Classify as 6A00.0 (mild).

Step 5: Documentation and Record

Document the following essential elements in the medical record:

1. Formal test results: Specific IQ scores and subscales, adaptive behavior percentiles
2. Developmental history: Milestones achieved (age), pattern of delays
3. Current functioning: Detailed description of abilities and limitations in each domain
4. Etiology: Identified or suspected causes (additional code when applicable)
5. Level of support needed: Specify type and intensity of supports required
6. Intervention plan: Therapies, special education, social services

Documentation example: "Patient with Intellectual Developmental Disorder, mild level (ICD-11: 6A00.0). WISC-V: Total IQ 62 (VCI=65, VSI=60, FRI=58, WMI=64, PSI=61). Vineland-3: Communication SS=60, Daily Living SS=62, Socialization SS=58, Adaptive Behavior Composite SS=59. Onset of delays identified at 18 months (not walking, few words). Etiology unclear after investigation (normal karyotype, negative microarray, brain MRI without structural changes). Currently attends 3rd grade in mainstream school with aide support and resource room. Plan: continuation of speech-language therapy 2x/week, occupational therapy 1x/week, psychoeducational follow-up, annual reassessment."

Complete Practical Example

Clinical Case:

Ana Silva, 8 years old, a 2nd grade elementary school student, was referred by her school to the neuropediatrics service due to significant learning difficulties and immature behavior compared to her peers. The teacher reports that Ana does not keep up with grade-level content, has difficulty understanding complex commands, takes much longer than her classmates to complete activities, and frequently needs individual assistance. Socially, she prefers to play with younger children and has difficulty with games that require rules or strategies.

Her mother reports that Ana has always been "slower" than her older brother. She sat at 10 months, walked at 18 months, and began speaking words at 24 months. Complete sphincter control only at 4 years of age. Currently, she still needs help choosing weather-appropriate clothing, cannot tie her shoes, has difficulty bathing independently (forgets to rinse the shampoo), and does not know how to count money or make simple purchases. The pregnancy was uneventful, delivery was vaginal at term, birth weight 3,200g. Normal newborn screening. Gross motor development currently adequate. No family history of intellectual disability or known genetic syndromes.

On examination, Ana is a cooperative girl with healthy appearance and no evident facial dysmorphisms. Head circumference at the 25th percentile for age. Neurological examination without focal abnormalities. Motor coordination adequate. During the consultation, she is communicative but with vocabulary limited for her age, simple sentences (4-5 words), difficulty with abstract concepts. When asked to draw a person, she draws a stick figure typical of a 4-5 year old child.

Step-by-Step Coding:

1. Initial analysis: Ana presents a history of delays since early childhood (onset during the developmental period ✓), difficulties in both academic and practical daily living skills (suggesting global adaptive impairment ✓), need for support above what is expected for her age (functional impact ✓). Initial criteria suggest possible IDI, indicating need for comprehensive formal evaluation.

2. Criteria evaluated:

   • Intellectual functioning: WISC-V administered, resulting in: VCI (Verbal Comprehension Index) = 64, VSI (Visuospatial Index) = 68, WMI (Working Memory Index) = 62, PSI (Processing Speed Index) = 66, Full Scale IQ = 63 (1st percentile, approximately 2.5 standard deviations below the mean)
   • Adaptive behavior: Vineland-3 completed with mother: Communication SS=61, Daily Living SS=58, Socialization SS=60, Adaptive Behavior Composite SS=58 (0.3rd percentile, approximately 2.7 standard deviations below the mean)
   • Exclusion of other causes: Bilateral audiometry normal, ophthalmological evaluation without abnormalities. Screening for ASD negative (CARS-2 = 18 points, no autism; social interaction adequate for cognitive level, no stereotypies). Structured family environment, no deprivation. Complete blood count, thyroid function, screening for inborn errors of metabolism normal.
   • Etiological investigation: Brain MRI without structural abnormalities. Karyotype 46,XX normal. Chromosomal microarray (SNP-array) without identified pathogenic variants. Etiology remains undetermined.

3. Code selected: 6A00.0 (Intellectual developmental disorder, mild)

4. Justification: Ana meets all diagnostic criteria for Intellectual Developmental Disorder: (1) Intellectual functioning significantly below average (IQ=63, < 2.3rd percentile); (2) Adaptive behavior significantly impaired in all evaluated domains (SS=58, < 2.3rd percentile); (3) Onset clearly during the developmental period (identifiable delays since 18 months); (4) Adequate exclusion of other conditions (sensory, autism, deprivation, treatable medical causes). Severity is classified as MILD based primarily on adaptive functioning: Ana can perform basic self-care with some supervision, communicates verbally in a functional manner, interacts socially (albeit at an immature level), has potential to develop basic academic skills, and with appropriate support may achieve significant independence in adult life, possibly including supported employment.

5. Documentation: "Patient Ana Silva, 8 years old, female, with diagnosis of Intellectual Developmental Disorder, mild level (ICD-11: 6A00.0).

Neuropsychological evaluation (WISC-V, administered on 01/15/2026): Full Scale IQ = 63 (1st Percentile, Mild Intellectual Disability classification). Subscales: VCI=64, VSI=68, WMI=62, PSI=66. Homogeneous profile of deficits, with no areas of functioning preserved significantly above the others.

Adaptive behavior evaluation (Vineland-3, informant: mother): Adaptive Behavior Composite SS=58 (0.3rd Percentile). Communication SS=61 (age equivalent: 5 years), Daily Living SS=58 (age equivalent: 4 years and 6 months), Socialization SS=60 (age equivalent: 5 years).

Developmental history: Slightly delayed motor milestones (sat 10m, walked 18m). Delayed language milestones (first words 24m, simple sentences 3 years). Late sphincter control (4 years). Consistent pattern of delays in all areas since early childhood.

Current functioning: Communicates verbally, but vocabulary and linguistic complexity below expected for 8 years (equivalent to 5-6 years). Partially independent self-care (dresses with help for selection and complex items, hygiene with supervision). Emerging academic skills (recognizes letters, reads simple words, counts to 20). Socializes appropriately with younger children, difficulty with peers. Does not manage money, does not perform complex household tasks.

Etiology: Undetermined after complete investigation (karyotype, microarray, MRI normal).

Differential diagnoses excluded: Hearing impairment (normal audiometry), visual impairment (normal ophthalmological evaluation), Autism Spectrum Disorder (negative CARS-2, preserved social interaction), environmental deprivation (structured family), treatable metabolic causes (normal screening).

Therapeutic plan:

• Education: Continuation in regular school with support from auxiliary teacher 20h/week + resource room attendance 4h/week. Individualized curricular adaptations. Focus on literacy, basic mathematics, and daily living skills.
• Speech-Language Pathology: 2x/week (focus on pragmatic language and narrative)
• Occupational Therapy: 1x/week (focus on daily living skills, fine motor skills)
• Educational Psychology: 1x/week (learning strategies, executive functions)
• Neuropediatric follow-up: semi-annual
• Neuropsychological re-evaluation: annual
• Family guidance: ongoing

Prognosis: With appropriate interventions, Ana is expected to achieve functional literacy, autonomy in self-care, adequate social skills, and in adult life may have supported employment, live semi-independently, and actively participate in the community. Moderate support will be necessary throughout life for complex tasks (financial management, important medical decisions, bureaucratic navigation)."

Related Codes

6A00.0: Intellectual developmental disorder, mild

IQ approximately 50-69. Greater level of potential independence. With adequate support, can achieve basic academic skills (up to 6th grade), work with minimal support, autonomy in self-care and semi-independent living in adulthood.

Differentiation: The mildest level; use when adaptive behavior indicates potential for significant independence.

6A00.1: Intellectual developmental disorder, moderate

IQ approximately 35-49. Requires moderate to substantial support. Can learn basic self-care, simple functional communication and prevocational skills. Work generally in sheltered workshops. Requires supervision in adulthood.

Differentiation: Use when support needs are moderate to substantial; complete independence unlikely.

6A00.2: Intellectual developmental disorder, severe

IQ approximately 20-34. Requires extensive to pervasive support. Very limited language, understanding of simple commands. Dependent in self-care (requires assistance). Does not acquire formal academic skills. Continuous supervision necessary.

Differentiation: Use when dependence is high and communication/self-care severely limited.

6A00.3: Intellectual developmental disorder, profound

IQ less than 20. Total or near-total dependence. Non-verbal or very basic communication. Frequently severe neurological, motor and sensory comorbidities. Intensive nursing care throughout life.

Differentiation: Most severe level; use when there is total dependence in all areas.

6A00.4: Intellectual developmental disorder, provisional

Use when criteria of age, behavior or reliability of assessment make it impossible to determine the level of severity. Common in very young children (< 4 years) or in situations where formal testing is not viable.

Differentiation: Temporary code; reassess when possible to specify severity.

6A00.Y: Other specified intellectual developmental disorder

Atypical cases that do not fit standard categories.

6A00.Z: Intellectual developmental disorder, unspecified

When there is insufficient information to specify the level of severity, but diagnosis of IDD is clear.

Differences with ICD-10

| Aspect | ICD-10 | ICD-11 (6A00) | Change | |---------|---------|---------------|---------| | Code | F70-F79 | 6A00 | Renaming and reorganization | | Nomenclature | Mental retardation | Intellectual developmental disorder | Respectful, non-stigmatizing language | | Criteria | IQ as primary criterion | Adaptive behavior as primary criterion | Emphasis on actual functioning | | Severity levels | Based primarily on IQ | Based primarily on adaptive behavior | More functional approach | | IQ ranges | Rigid (Mild: 50-69, etc.) | Approximate, flexible | Recognizes IQ limitations | | Etiology | Separate codes for some causes | Optional additional code for etiology | Simplification, greater flexibility |

Explanation of main changes:

ICD-10 used the term "mental retardation" (F70-F79), which was replaced by "intellectual developmental disorder" in ICD-11 due to concerns about stigma and negative connotations. More important than the terminological change, ICD-11 repositions adaptive behavior as the PRIMARY criterion for determining severity level, rather than IQ. This change reflects the recognition that real-life functioning is more clinically relevant than intelligence test scores, which may vary according to cultural, linguistic, and motivational factors.

IQ ranges in ICD-11 are described as "approximate" rather than rigid cutoffs, acknowledging the standard error of measurement in tests and the possibility of discrepancies between IQ and adaptive functioning. The system also simplified the coding of etiologies: instead of having separate codes for each specific cause (as in ICD-10), ICD-11 allows the use of an optional additional code when the etiology is known.

Another important change is the inclusion of code 6A00.4 (provisional), recognizing that in very young children or in special situations, it may not be possible to determine the severity level with confidence, but the diagnosis of IDD itself can be established.

Frequently Asked Questions

Q: What is the difference between intellectual developmental disorder and specific learning disorder?

A: The fundamental difference lies in the SCOPE of impairment. In Intellectual Developmental Disorder (6A00), there is GLOBAL impairment in both intellectual functioning and adaptive behavior - the person presents difficulties not only academically, but also in daily living skills (self-care, money management, community navigation), social skills (making friends, understanding social norms), and conceptual skills (reasoning, problem-solving). For example, a child with mild IDD may have an IQ of 65 AND also need help choosing clothes appropriate for the weather, have difficulty shopping alone, and function socially at a more immature level.

In Specific Learning Disorder (6A03), general intellectual functioning is NORMAL (IQ ≥ 85), and difficulties are SPECIFIC to reading, writing, or mathematics, without significant impairment in other areas of life. For example, a child with dyslexia may have an IQ of 110, excellent social skills, complete autonomy in daily activities, but specifically difficulty learning to read despite adequate intelligence. The child with dyslexia functions perfectly outside the academic context; the child with IDD presents limitations in multiple areas of life, both inside and outside school.

Q: Can young children (under 5 years old) receive this diagnosis?

A: Yes, but with CAUTION and IMPORTANT CAVEATS. Children under 5 years old can receive the diagnosis of Intellectual Developmental Disorder when there is: (1) Very significant and consistent delays in multiple developmental areas identified through age-appropriate testing (e.g., Bayley-III, MSEL); (2) Clearly identified genetic or biological etiology known to cause IDD (e.g., Down syndrome, Fragile X syndrome); (3) Severe and evident impairment of adaptive development.

HOWEVER, in very young children (< 4 years) without known etiology, it is preferable to use the code 6A00.4 (provisional) or diagnoses of "global developmental delay," because: (a) development is very dynamic at this stage; (b) early interventions can significantly modify the trajectory; (c) tests have lower predictive value; (d) it is difficult to differentiate transient delays from permanent deficits. Periodic reassessments (annual) are ESSENTIAL to confirm or revise the diagnosis as the child develops and to adjust the severity level. Diagnosis in young children should never be given lightly, but neither should it be denied when clearly justified, as it enables access to crucial early interventions.

Q: Is a specific IQ required for each severity level?

A: NO, IQ ranges are APPROXIMATE and NOT rigid in ICD-11. This is a fundamental change from ICD-10. ICD-11 recognizes that IQ has important limitations: (1) standard error of measurement of ±5 points; (2) variation in performance according to motivation, fatigue, anxiety; (3) cultural and linguistic influences; (4) does not necessarily capture functioning in real life.

Therefore, the severity level (mild, moderate, severe, profound) should be determined PRIMARILY by ADAPTIVE BEHAVIOR, not by IQ. For example, if a person has an IQ of 48 (technically in the "moderate" range) BUT can live semi-independently, work with minimal support, and manage complete self-care, it may be more appropriate to classify as "mild" if adaptive behavior indicates so. Conversely, someone with an IQ of 52 (technically "mild") but with severe limitations in adaptive functioning may be classified as "moderate."

The assessment should be HOLISTIC, considering: scores on adaptive behavior tests (Vineland, ABAS), clinical observation of actual functioning, reports from caregivers/teachers about autonomy in natural contexts, and ability to respond to environmental demands. IQ is important data, but it is NOT the sole decisive criterion.

Q: Can people with IDD work?

A: YES, absolutely! The ability to work varies according to severity level, but people with IDD can and SHOULD have employment opportunities with appropriate supports:

• Mild IDD (6A00.0): Many people with mild IDD work in competitive jobs in the open market, especially in positions requiring practical skills and well-established routines (kitchen assistant, cleaning assistant, stock clerk, simple machine operator, gardening assistant). With initial job coaching and workplace supports (simple written instructions, routine supervision), they can become reliable and valued workers. Supported employment and customized employment are very effective modalities.

• Moderate IDD (6A00.1): Often work in sheltered workshops or supported work programs, performing tasks such as simple assembly, packaging, material sorting, team gardening services. With appropriate training and continuous supervision, they can perform productive and meaningful work.

• Severe/Profound IDD (6A00.2/6A00.3): Can participate in occupational activities and day centers focusing on basic skills, recreational activities, and personal development, although generally not in formal paid employment.

It is important to emphasize: work is not only about income, but about DIGNITY, PURPOSE, SOCIAL INCLUSION, and SKILL DEVELOPMENT. Public policies should encourage and fund supported employment programs, ensuring that people with IDD have real opportunities to contribute to society according to their abilities.

Q: How to address the issue of legal autonomy and guardianship/trusteeship?

A: The issue of civil capacity of people with IDD is complex and should be addressed in an INDIVIDUALIZED manner, avoiding generalizations. Essential points:

Principles of the Convention on the Rights of Persons with Disabilities (UN): (1) Presumption of capacity; (2) Support for decision-making instead of decision substitution whenever possible; (3) Supported decision-making as first option; (4) Guardianship as last resort, limited to what is strictly necessary.

Supported Decision-Making (SDM): Modality in which the person with IDD maintains legal capacity, but CHOOSES trusted people to help them understand information, evaluate options, and express preferences. Preferable to guardianship for people with mild IDD and many with moderate IDD.

Guardianship: When necessary (generally in severe/profound IDD or moderate with severe limitations), it should be: (a) LIMITED to specific necessary acts (partial guardianship); (b) REVIEWED periodically; (c) Exercised respecting the will and preferences of the ward when possible.

Assessment: It is not automatic from IDD diagnosis! It requires specific assessment by a multidisciplinary team (physician, psychologist, social worker) and judicial decision. A person with mild IDD generally does NOT need guardianship - can sign contracts, marry, vote, make medical decisions with family/professional support as needed.

Sterilization: MUST NEVER be imposed. It is the right of the person with IDD to have accessible information about sexual/reproductive health and make choices about contraception with support. Compulsory sterilization is a violation of human rights.

Important Aspects for Professionals

For Physicians

• Diagnostic evaluation of IDD requires adequate time (multiple consultations), detailed developmental history, and application of standardized instruments - it is not a diagnosis that can be established in a single 20-minute consultation
• Always investigate etiology (karyotype, chromosomal microarray, brain MRI, metabolic screening as indicated), as identifying the cause can: (a) guide genetic counseling; (b) identify treatable conditions; (c) predict comorbidities
• Systematically assess frequent comorbidities: epilepsy (20-30% in moderate/severe IDD), psychiatric disorders (anxiety, depression, ADHD), sensory problems (vision, hearing), obesity, orthopedic problems
• The severity level may CHANGE throughout development - periodic reassessments are essential
• Communicate the diagnosis to the family with sensitivity, emphasizing potential and interventions, not just limitations

For Psychologists

• ALWAYS use UPDATED and APPROPRIATELY STANDARDIZED tests for the population - outdated tests overestimate deficits
• The evaluation must MANDATORY include intelligence testing (WISC-V, WAIS-IV) AND adaptive behavior scale (Vineland-3, ABAS-3) - neither alone is sufficient
• Document not only scores, but also QUALITATIVE OBSERVATIONS: problem-solving style, strategies used, response to assistance, persistence
• In culturally diverse populations or those with language barriers, consider nonverbal tests (Leiter-3, TONI) and cautious interpretation
• The report should be FUNCTIONAL and USEFUL for intervention planning, not merely descriptive

For Educators

• Students with mild IDD may benefit from regular classroom education with supports (teaching assistant, curriculum adaptations, resource room) - inclusion is a right, not a favor
• Curricula should emphasize FUNCTIONAL SKILLS: functional reading, mathematics applied to daily life, social skills, transition to adulthood
• Expectations should be HIGH but REALISTIC - avoid both underestimation (negative self-fulfilling prophecy) and excessive pressure
• Close partnership with family is essential for generalization of skills learned at school to home and community
• Transition planning should begin early (14-16 years), including vocational exploration, independent living skills, self-determination

For Managers and Policy Makers

• Investment in early intervention (0-6 years) is COST-EFFECTIVE - every dollar invested saves 7-13 dollars in future costs
• Supported employment programs should be prioritized - people with IDD want to work and can be productive with supports
• Long-term institutionalization should be eliminated - community-based supported housing is more humane and economically viable
• Data systems should track not only prevalence, but OUTCOMES: employment rate, community integration, quality of life
• Policies should be evidence-based, not stereotype-based - people with IDD are capable of much more than historically believed

References

• World Health Organization (WHO). ICD-11 - International Classification of Diseases, 11th Revision. 2024.
• American Association on Intellectual and Developmental Disabilities (AAIDD). Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports. 12th Edition, 2021.
• Schalock RL, Luckasson R, Tassé MJ. An Overview of Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports (12th ed.). Am J Intellect Dev Disabil. 2021;126(6):439-442.
• Boat TF, Wu JT, eds. Mental Disorders and Disabilities Among Low-Income Children. Washington (DC): National Academies Press; 2015.
• Maulik PK, Mascarenhas MN, Mathers CD, Dua T, Saxena S. Prevalence of intellectual disability: a meta-analysis of population-based studies. Res Dev Disabil. 2011;32(2):419-436.

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Article updated according to ICD-11 version 2024-01 Technical content reviewed by specialists in neuropsychology and medical coding