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Did you know why an IQ below 70 is considered a key indicator of intellectual disability?
Intellectual disability (ID), also known as general learning disability, is usually clearly discovered in childhood. This is a common neurodevelopmental disorder, which is mainly characterized by significant impairments in intelligence and adaptive functions. By definition, children with intellectual disabilities usually have an intelligence quotient (IQ) below 70 and deficits in at least two adaptive behaviors, which are critical factors affecting daily life.
According to DSM-5 standards, intellectual functions include reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience.
Deficits in these functions must be determined through clinical evaluation and individual standardized IQ tests. Adaptive behaviors, on the other hand, include social, developmental, and practical skills that people learn to perform the tasks of daily living. Deficient adaptive functioning often impedes an individual's ability to live independently and to be socially responsible.
Classification of intellectual disabilities
Intellectual disability can be divided into comprehensive intellectual disability and non-synthetic intellectual disability. Syndrome is an intellectual disability associated with other medical and behavioral symptoms, while non-syndromic intellectual disability is an intellectual disability that occurs in the absence of other abnormalities. Common examples of combined intellectual disabilities include Down syndrome and fragile X syndrome. According to recent data, intellectual disability affects approximately 2-3% of the general population, with 75% to 90% having mild intellectual disability.
Among this group, about 30% to 50% of the cases are non-synthetic intellectual disabilities, and about a quarter of the cases are caused by genetic diseases.
Signs and symptoms of intellectual disability
Signs of intellectual disability are often evident in childhood and include deficiencies in mental, social and daily living abilities, and may lag behind compared with peers.
Some early signs may include:
- Delay or failure to achieve developmental milestones in motor skills (e.g., sitting, crawling, walking)
- Slowness in learning to speak or persistent difficulty expressing language
- Insufficient self-care skills (such as dressing, bathing, feeding oneself)
- Poor planning and problem-solving skills
- Behavioral and social issues
Comorbidity with other diseases
There are many common clinical features between intellectual disability and autism spectrum disorder (ASD), which can cause diagnostic confusion. Often, the overlap of these two disorders affects an individual's health and quality of treatment.
According to research, about 30% of people with autism also have intellectual disabilities. Appropriate recognition and differentiation of these two states is critical to providing the correct treatment.
Causes of intellectual disability
Intellectual disability has various causes, and in about one-third to half of cases in children, the cause is unknown. Other possible causes include genetic defects, problems during pregnancy, difficulties during delivery, and exposure to harmful substances. Notably, iodine deficiency is considered one of the major preventable causes of intellectual disability, affecting many populations in developing countries.
Diagnosis process
A diagnosis of intellectual disability requires three main criteria: significant intellectual limitations, significant limitations in adaptive behavior, and evidence of onset in childhood or adolescence. Assessment of intelligence is usually done through an IQ test plus a comprehensive assessment of adaptive functioning.
Current IQ testing standards assess intelligence levels based on past data and consider an individual's adaptive functioning in the diagnostic process.
Management and Support
Intellectual disability is considered a disability rather than a disease, and there is currently no cure. However, with appropriate support and education, most individuals can learn many skills and live independently in life. Many organizations provide a variety of supports, including life skills training, social skills development, vocational training, etc., to promote the independence of people with intellectual disabilities.
In all aspects of life, joint efforts from all sectors of society are needed to improve the quality of life and social adaptability of these people. Looking back on the above, have you ever thought about how to better support those with intellectual disabilities?
