Cognitive Deficits

Background

Cognitive deficits in children range from profound intellectual impairments with minimal functioning to mild impairment in specific operations. To understand the concept of cognitive deficit, some primary issues in the measurement of cognitive function must be understood.

Cognitive deficit is an inclusive term used to describe impairment in an individual’s mental processes that lead to the acquisition of information and knowledge, and drive how an individual understands and acts in the world. The following areas constitute domains of cognitive functioning:

• Attention
• Decision making
• General fund of knowledge
• Judgment
• Language
• Memory
• Perception
• Planning
• Reasoning
• Visuospatial

Intellectual disability

Intellectual disability (formerly known as intellectual disability) is the current diagnostic term in the DSM-5 that describes the onset of both intellectual and adaptive functioning deficits during the developmental period. ^[1] In the United States, the developmental period refers to the span of time prior to the age 18. Children with this disorder may evidence delayed developmental milestones, while milder levels may not become identified until school age. Intellectual disability is nonprogressive and generally lifelong; however, concurrence with specific genetic disorders may manifest with periods of cognitive deterioration.

Deficits in intellectual functioning may be confirmed by clinical assessment and standardized intelligence testing. Individuals with IQ scores of less than 70 fall in a very low range of functioning and the bottom two percent of same-aged individuals. Professionals, such as psychologists, involved in assessment of intellectual functioning should also consider linguistic diversity and cultural differences when determining the validity of IQ scores.

Deficits in adaptive functioning involve conceptual, practical and social skills deficits and limit an individual’s ability to function in one or more activities of daily living across multiple environments. Adaptive functioning may be assessed by a structured interview or caregiver report measure such as the following:

• Adaptive Behavior Assessment System, Third Edition (ABAS-III)

• Scales of Independent Behavior - Revised (SIB-R)

• Vineland Adaptive Behavior Scales, Second Edition (Vineland-II)

Diagnostic criteria (DSM-5)

The four revised severity specifiers in the DSM-5 that may be applied to a diagnosis of intellectual disability are Mild, Moderate, Severe and Profound. Severity is based on the level of adaptive functioning rather than IQ score. ^[1]

Mild is used to refer to IQ scores of approximately 55-70. Some support with complex daily living tasks, health care and legal decisions, and vocational training is warranted. Immature social development and social judgment is demonstrated in addition to difficulties in learning academic skills with support needed in order to meet age-related expectations.

Moderate previously referred to IQ scores of approximately 40-55. Extended teaching of care for basic personal needs may be required before an individual may obtain independence. Ongoing supports for household tasks are expected in addition to the need for vocational supports. Social and communicative behaviors may be significantly less complex than peers and social judgment is typically limited. Language and pre-academic skills may develop slowly and the learning rate of academic skills is significantly behind peers.

Severe formerly indicated IQ scores between 25 and 40. Support is expected for all activities of daily living and supervision is needed at all times. Spoken language may be quite limited and may require augmentation through devices or other means. Attainment of conceptual skills is vey limited with respect to written language, numbers, quantity or time.

Profound previously referred to IQ scores below 25. The individual is dependent on others for all aspects of daily living. Very limited understanding of symbolic communication (speech and gesture) is typical and needs may be expressed through nonverbal means. Use of objects may be goal-directed and visuospatial skills such as matching or sorting may be acquired. Co-occuring motor and sensory impairments may impede functioning.

An Unspecified Intellectual Disability may be utilized to describe an individual’s (over the age of 5) functioning when assessment of the degree of intellectual deficit by available procedures or testing is deemed impossible for various reasons (locomotor disability, severe problem behaviors, sensory impairments, etc).

Differential diagnosis

Intellectual disability is categorized as a neurodevelopmental disorder in the DSM-5 and is distinguished from the neurocognitive disorders, communication disorders, specific learning disorders, autism spectrum disorders, or global developmental delay. ^{[1, 2]} A diagnosis of intellectual disability should not be assumed on the basis of a specific genetic or medical condition but may be noted as a concurrent diagnosis pending formal evaluation.

Co-occurring disorders

Co-occurring mental, neurodevelopmental, medical and physical conditions frequently occur in conjunction with intellectual disability. The most common co-occurring disorders with intellectual disability are ADHD, depressive and bipolar disorders, anxiety disorders, autism spectrum disorder, stereotypic movement disorder and impulse-control disorders. ^[3]

Exposure to risk factors and the timing (prenatal, perinatal, postnatal) of exposures contribute to present-day thinking about causes of intellectual disability.

Prenatal causes may include:    

• Genetic syndromes and chromosomal disorders
• Metabolic conditions
• Brain malformations
• Maternal disease
• Environmental influences (teratogens, toxins, substances)

Perinatal causes may involve events during labor and delivery leading to encephalopathy.

Postnatal causes may include:

• Hypoxic ischemic injury
• Traumatic brain injury
• Infections ^{[4, 5]}
• Demyelinating disorders
• Seizure disorders
• Severe and chronic social deprivation,
• Toxic metabolic syndromes
• Intoxications (eg, lead, mercury)

While there is no cure for intellectual disability, early identification, services and supports play a crucial role in a child’s development and can enable an individual to thrive throughout their lifetime. Services for children with intellectual disability and their families seek to provide adequate support to allow for full inclusion in the community.

The evaluation and classification of an intellectual disability is conducted in the context of a comprehensive assessment of intellectual capacity and adaptive functioning prior to the age of 18 years.

Evaluation for co-occurring disorders and associated medical and genetic conditions may also be warranted. As such, thorough assessment may involve a number of professionals including school or clinical psychologists, developmental pediatricians, and other physician specialists.

Measurement of intellectual functioning is typically conducted by a psychologist using a norm-referenced instrument. Ethical standards require that the most recent edition of the test be used and providers have a one-year grace period from the publication date of a new edition to upgrade. Test selection may be driven by the child’s age, verbal ability and motor ability. Other considerations for hearing/visual impairments may also be necessary.

Developmental assessment instruments

Developmental assessment instruments include the following:

• 0-42 months: Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III), 2005

• 0-68 months: Mullen Scales of Early Learning, AGS Edition (Mullen), 1995

Verbal intellectual assessment instruments

Verbal intellectual assessment instruments include the following:

• Differential Ability Scales, Second Edition (DAS-II), 2007

• Reynolds Intellectual Assessment Scales (RIAS), 2003

• Stanford Binet Intelligence Scales, Fifth Edition (SB-5), 2003

• Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V), 2014

• Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV), 2012

• Woodcock Johnson IV Tests of Cognitive Abilities (WJ IV-COG), 2014

Nonverbal intellectual assessment instruments

Nonverbal intellectual assessment instruments include the following:

• Comprehensive Test of Nonverbal Intelligence, Second Edition (C-TONI-2) 2009

• Differential Ability Scales, Second Edition (DAS-II) 2007

• Leiter International Performance Scale, Third Edition (Leiter-III), 2013

• Stanford Binet Intelligence Scales, Fifth Edition (SB-5), 2003

• Universal Nonverbal Intelligence Test (UNIT), 1998

• Wechsler Nonverbal Scale of Ability (WNV), 2006

Screening tools

Screening tools also may be used to estimate a child’s cognitive ability in a briefer format than a formal, full-length IQ test.   

• Developmental Profile 3 (DP-3), 2007

• Kaufman Brief Intelligence Test, Second Edition (KBIT-2), 2004

• Slosson Intelligence Test-R3 (SIT-R3), 2002

• Wechsler Abbreviated Scale of Intelligence, Second Edition (WASI-II), 2012

• Wide Range Intelligence Test (WRIT), 1999

Adaptive functioning assessment measures

Measurement of adaptive functioning usually involves a structured interview with a caregiver or a caregiver report questionnaire to quantify the child’s independence with activities of daily living across conceptual, practical and social domains.

• Adaptive Behavior Assessment System, Third Edition (ABAS-III)

• Scales of Independent Behavior, Revised (SIB-R)

• Vineland Adaptive Behavior Scales, Second Edition (Vineland-II)

A multidisciplinary approach is recommended to identify and manage any concurrent conditions, academic performance, social/behavioral functioning, and independent living skills.

Early intervention and appropriate school placement are essential to meet the child at his or her intellectual level and proceed at his or her pace towards specific objectives and goals. The Individuals with Disabilities Education Act (IDEA) is the federal law that secures special education services for children with disabilities, such as intellectual disability, from the time they are born until they graduate from high school. IDEA is divided into four parts (A-D) as follows: ^[6]

• Part A: definition of terms, disorders that are included/excluded under the law
• Part B: rules and regulations school and state agencies must follow in order to receive federal funding
• Part C: provision of early intervention services for children 0-3 years of age
• Part D: education, training and best practices for those who work with children under IDEA

Children aged 0-3 years with cognitive deficits are served by Part C, which describes the Early Intervention Program for Infants and Toddlers with Disabilities. Services that may be included in this program are family training, counseling, home visits, speech-language services, occupational therapy and physical therapy. Pediatrician referral to a local Part C early intervention agency is an important step in the treatment process.

Once a child reaches age 3, referral from early intervention to the public school systems’ special education department is made. An Individualized Education Program (IEP) may be developed to transition the child to a special education preschool setting and may involve a specific list of special services, modifications or accommodations needed in order for the child to be educated. IEPs are classified under one of thirteen categories; that is, the child has been found by the school system to have qualified for special education services under one of these thirteen conditions, which adversely affects the child’s academic performance. ^[7]

• Autism ^[8]
• Blindness
• Deafness
• Emotional disturbance
• Hearing impairment
• Intellectual disability
• Multiple disabilities
• Orthopedic impairment
• Other health impaired
• Specific learning disability
• Speech or language impairment
• Traumatic brain injury
• Visual impairment

Prior to age 6-7 years, children with cognitive deficits are likely to have an IEP for developmental delay, but this classification expires at age 7 necessitating the IEP team to reclassify a child following a school-based evaluation with one of the categories mentioned above. It is important to note that psychoeducational testing completed by public schools does not result in a medical, psychiatric or psychological diagnosis; results of school evaluations are utilized to determine eligibility for services and placement and academic planning in the school setting. However, test results may be forwarded to the child’s primary care physician or other outpatient providers for interpretation and diagnostic conclusions.

Children with IEPs are permitted to remain in the public school system until the age of 21. As the child progresses, the IEP will be revised to include transitional planning (around age 14-15 years) to help the child and family prepare for life after high school.

Local community mental health centers and agencies may provide case management for individuals with intellectual disability to assist in the provision of resources and community-based services. Application for Supplemental Security Income (SSI) for the child may be warranted. Caregivers may wish to extend guardianship over a child with an intellectual disability, pending severity, in order to have oversight of the child’s medical, legal and financial decisions after the child turns 18 years old.

Ongoing monitoring and communication between a pediatrician and a developmental pediatrician is highly recommended. Referral to additional services such as a counselor/therapist, speech therapist, occupational therapist or child psychiatrist may be considered. Outpatient behavioral therapy, parent management training, social skills groups, and medication management are additional mental health services that may be warranted.

Support groups and organizations

American Association on Intellectual and Developmental Disabilities (AAIDD)

501 3rd Street, NW, Suite 200

Washington, DC 20001

American Speech-Language-Hearing Association: This organization provides information on speech and language disorders and referrals to certified speech-language therapists.

American Speech-Language-Hearing Association

10801 Rockville Pike

Rockville, MD 20852

(800) 638-8255

Attention Deficit Information Network: This organization provides up-to-date information on current research and regional meetings. They also offer aid in finding solutions to practical problems faced by adults and children with an attention disorder.

Attention Deficit Information Network

475 Hillside Avenue

Needham, MA 02194

(781) 455-9895

Candlelighters Childhood Cancer Foundation: This organization provides information and support for children who are treated for cancer and later experience learning disabilities.

Candlelighters Childhood Cancer Foundation

7910 Woodmont Avenue, Suite 460

Bethesda, MD 20814

(800) 366-2223

Center for Mental Health Services Office of Consumer, Family, and Public Information: This new national center, a component of the US Public Health Service, provides a range of information on mental health, treatment, and support services.

Center for Mental Health Services Office of Consumer, Family, and Public Information

5600 Fishers Lane, Room 15-81

Rockville, MD 20857

(301) 443-2792

Children with Attention Deficit Disorders (CHADD): CHADD runs support groups and publishes 2 newsletters on attention disorders for parents and professionals.

Children with Attention Deficit Disorders (CHADD)

8181 Professional Place, Suite 201

Landover, MD 20785

(800) 233-4050

Council for Exceptional Children: This organization provides publications for educators. They can also provide referral to ERIC Clearinghouse for Handicapped and Gifted Children.

Council for Exceptional Children

11920 Association Drive

Reston, VA 22091

(888) 232-7733

Federation of Families for Children's Mental Health: This organization provides information, support, and referrals through federation chapters nationwide. This national parent-run organization focuses on the needs of children with broad mental health problems.

Federation of Families for Children's Mental Health

1021 Prince Street

Alexandria, VA 22314

(703) 684-7710

HEATH Resource Center: This is a national clearinghouse on post–high school education for people with disabilities.

HEATH Resource Center

American Council on Education

1 Dupont Circle, Suite 800

Washington, DC 20036

(800) 544-3284

Learning Disabilities Association of America: This organization provides information and referral to state chapters, parent resources, and local support groups. They also publish news briefs and a professional journal.

Learning Disabilities Association of America

4156 Library Road

Pittsburgh, PA 15234

(412) 341-1515

Library of Congress National Library Service for the Blind and Physically Handicapped: This organization publishes Talking Books and Reading Disabilities, a fact sheet outlining eligibility requirements for borrowing talking books.

Library of Congress National Library Service for the Blind and Physically Handicapped

1291 Taylor Street NW

Washington, DC 20542

(800) 424-8567

National Alliance for the Mentally Ill Children and Adolescents Network (NAMICAN): This organization provides support to families through personal contact and support meetings. They also provide education regarding coping strategies, reading material, and information about effective and ineffective practices.

National Alliance for the Mentally Ill Children and Adolescents Network

2101 Wilson Boulevard, Suite 302

Arlington, VA 22201

(800) 950-NAMI

National Association of Private Schools for Exceptional Children: This organization provides referrals to private special education programs.

National Association of Private Schools for Exceptional Children

1522 K Street NW, Suite 1032

Washington, DC 20005

(202) 408-3338

National Center for Learning Disabilities: This organization provides referrals and resources. It publishes Their World, a magazine describing true stories on ways children and adults cope with learning disabilities.

National Center for Learning Disabilities

381 Park Avenue South, Suite 1420

New York, NY 10016

(888) 575-7373

National Information Center for Children and Youth with Disabilities: This organization publishes a newsletter and arranges workshops. It also advises parents regarding the laws that entitle children with disabilities to special education and other services.

National Information Center for Children and Youth with Disabilities

PO Box 1492

Washington, DC 20013

(800) 695-0285

International Dyslexia Association: This organization answers individual questions on reading disability. They provide information and referrals to local resources.

International Dyslexia Association

Chester Building, Suite 382

8600 LaSalle Road

Baltimore, MD 21286-2044

(410) 296-0232

Other resources

Facts About Dyslexia

National Institute of Child Health and Human Development

Building 31, Room 2A32

9000 Rockville Pike

Bethesda, MD 20892

(800) 370-2943

Developmental Speech and Language Disorders—Hope through Research

National Institute on Deafness and Other Communicative Disorders

PO Box 37777

Washington, DC 20013

(800) 241-1044