WHAT IS INTELLECTUAL DISABILITY? By Dr. Nadeem Ghayas
July 21, 2024
Intellectual disability (ID), previously known as mental retardation, is a developmental disorder which results in marked impairments in both intellectual functions and adaptive behaviors. These impairments arise during the developmental period, generally prior to an age of 18 years (American Psychiatric Association [APA] 2013). Intellectual disabilities have an impact on cognitive abilities, including the ability to reason, solve problems, think abstractly, judge, and learn academically, and also on everyday practical skills, such as communication, social interaction, and independent living.
DEFINITION OF INTELLECTUAL DISABILITY
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), intellectual disability is diagnosed based on three main criteria (APA, 2013):
1. Deficiencies in intellectual functioning:
Intellectual functioning deficits are defined as deficiencies in the ability to reason, plan, problem-solve, think abstractly, and learn academically.
2. Deficiencies in adaptive functioning:
Deficiencies in adaptive functioning define a person’s inability to perform at developmental and/or sociocultural standards of personal independence and social responsibility.
3. Onset during the developmental period:
A diagnosis of intellectual disability requires that the condition begin prior to an age of 18 years.
Additionally, the World Health Organization (WHO) describes intellectual disability as a condition where there is a reduced ability to understand or comprehend new or complex information; and, to learn and utilize new skills; which ultimately results in reduced independence (WHO 2019).
INTELLECTUAL FUNCTIONING AND COGNITIVE LIMITATIONS
Intellectual functioning is defined as general mental ability, which includes the following:
o Reasoning and logical thinking
o Problem solving
o Planning and decision making
o Academic learning
o Understanding abstract concepts
Standardized intelligence tests are commonly used as part of the assessment process. However, the diagnosis of an individual with intellectual disability does not rely solely on IQ scores. The functional performance of an individual in their natural environment is just as important (Schalock et al. 2010).
ADAPTIVE BEHAVIOR AND DAILY LIVING SKILLS
Adaptive behavior refers to the conceptual, social, and practical skills that people learn and utilize in their daily lives. These skills are categorized into three distinct domains:
- CONCEPTUAL SKILLS
• Language and communication
• Reading and writing
• Money management
• Time concepts
2. SOCIAL SKILLS
• Interpersonal communication
• Social responsibility
• Self-esteem
• Ability to follow rules and avoid being a victim
3. PRACTICAL SKILLS
• Personal hygiene
• Dressing and eating
• Household chores
• Workplace skills
• Safety awareness
Impairments in these skill areas directly influence an individual’s degree of independence and participation in their community (Schalock et al. 2010).SEVERITY LEVELS OF INTELLECTUAL DISABILITY
The severity of an individual’s intellectual disability varies greatly. The DSM-5 categorizes ID into four different levels based on an individual’s level of adaptive functioning and not strictly on IQ scores (APA 2013):
MILD INTELLECTUAL DISABILITY
• Individuals may reach the same level of academic achievement as students who have completed elementary school.
• They can usually maintain independent living with minimal assistance.
• They will likely need assistance with complex life choices.
MODERATE INTELLECTUAL DISABILITY
• Noticeable developmental delays were evident in early childhood.
• Individuals will likely need continued assistance in performing daily living activities and working.
SEVERE INTELLECTUAL DISABILITY
• Significant impairments in communication and self-care.
• Continued assistance is necessary in many environments.
PROFOUND INTELLECTUAL DISABILITY
• Limited understanding of symbolic communication.
• Individuals will require intense, lifetime assistance and supervision.
An individual’s level of severity is determined by the amount of assistance they require to function in their daily life.
CAUSES OF INTELLECTUAL DISABILITY
There are numerous reasons for an individual’s intellectual disability and may be present prior to, during, or postnatally. Some of the more common causes include:
GENETIC CONDITIONS
• Down syndrome
• Fragile X syndrome
• Other chromosomal anomalies
PRENATAL FACTORS
• Maternal infections
• Malnutrition
• Exposure to alcohol or toxins
• Lack of prenatal care
PERINATAL FACTORS
• Birth complications
• Oxygen deprivation
POSTNATAL FACTORS
• Brain injuries
• Severe infections
• Exposure to environmental toxins
• Extreme malnutrition
In some instances, the specific cause of an individual’s intellectual disability cannot be identified (WHO 2019).
DIAGNOSIS AND ASSESSMENT
Diagnosing an individual with intellectual disability involves:
• Standardized IQ testing
• Evaluation of adaptive functioning
• Review of developmental history
• Medical evaluation
Early detection is crucial to provide adequate interventions. Often, assessments of individuals suspected of having an intellectual disability involve multidisciplinary teams including psychologists, pediatricians, special educators, and speech therapists.
IMPORTANCE OF EARLY INTERVENTION AND SUPPORT
Early intervention has been shown to greatly enhance the quality of an individual’s development and overall quality of life. Examples of potential support services include:
• Special education programs
• Speech and language therapy
• Occupational therapy
• Behavioral interventions
• Family counseling
Previous research indicates that providing each individual with an educational plan tailored specifically to his/her needs, along with structured support, can lead to greater independence and participation in social activities (Schalock et al. 2010).
CONCLUSION
Intellectual disability is a developmental disorder characterized by significant impairments in intellectual functioning and adaptive behavior, with onset prior to an age of 18 years. It impairs an individual’s ability to reason, learn, communicate effectively, and perform daily living tasks. Additionally, intellectual disability can vary greatly in terms of its severity, from mild to profound, depending upon the level of assistance an individual requires to function.
While an individual with intellectual disability may have a lifelong condition, diagnosing the condition at an early age, developing an individualized educational plan, and utilizing community resources can greatly enhance an individual’s independence, dignity, and overall quality of life.
Understanding intellectual disability in a strengths-based and supportive manner is vital to promote inclusion and equitable opportunities for all individuals.
References
1. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). American Psychiatric Publishing.
Schalock, R. L., Borthwick-Duffy, S. A., Bradley, V. J., Buntinx, W. H. E., Coulter, D. L., 2. Craig, E. M., … Yeager, M. H. (2010). Intellectual disability: Definition, classification, and systems of supports (11th ed.). American Association on Intellectual and Developmental Disabilities.
3. World Health Organization. (2019). International classification of diseases for mortality and morbidity statistics (11th rev.). WHO.