Intellectual Disability

What is Intellectual Disability?

People with intellectual disabilities have brain development issues that lead to difficulties in thinking and adapting to daily life. These disabilities begin at birth and become noticeable before a person turns 22. They can come with a range of related problems, such as mental health issues like depression or anxiety, brain development disorders like autism or attention deficit hyperactivity disorder (ADHD), neurological conditions like cerebral palsy in infants, and medical problems like meningitis.

“Intellectual Functioning” is another term for intelligence. It involves various mental tasks, like problem-solving, learning, verbal communication and more. It’s expressed through capabilities, behaviors, thoughts, and feelings. Basically, intellectual functioning is a person’s overall ability to understand and interact with the world around them.

You can measure intellectual functioning with an IQ score. This score comes from standardized IQ tests specifically designed to evaluate human intelligence. The average IQ score usually sits around 100. If a person scores 70 or below (which is significantly below the average), it suggests they have intellectual limitations.

Adaptive behavior refers to the skills necessary to function in everyday life. Social skills are part of it and include things like interaction with others, understanding social norms, and following laws. Conceptual skills are important too, which involve understanding time, money, and language. Practical skills such as using tools and interacting with others in daily tasks are also part of adaptive behavior. These skills develop over time, becoming more intricate as a person ages. There are validated tools out there that can be used to measure a person’s adaptive behavior.

What Causes Intellectual Disability?

There are two main causes behind intellectual disability: genetic abnormalities and exposure to certain environments. Genetic abnormalities can be due to a mutation within a single gene, variations in the number of gene copies, or irregularities in the chromosomes. This can lead to birth defects in metabolism, the nervous system’s development, or nervous system degeneration. Regarding environmental exposure, it can be the pregnant mother getting exposed to toxins/infectious agents, unregulated maternal medical conditions, complications during childbirth, and trauma/exposure to toxins or infectious agents after birth. The most common preventable cause of intellectual disability due to environmental factors is fetal alcohol syndrome, while the most common chromosomal and genetic causes are Down syndrome and Fragile X syndrome respectively.

Certain genetic abnormalities can cause birth defects in metabolism, leading to toxic substances accumulating in the body and causing intellectual disability along with other behavioral problems. One such condition is Phenylketonuria (PKU), which arises in about 0.01% of newborns mainly due to a defect in the phenylalanine hydroxylase gene. This defect stops the liver from converting phenylalanine into para-tyrosine, causing phenylalanine to build up and lead to intellectual disability. Even though the neurological damage from PKU is irreversible, it can be prevented. Screenings for PKU are mandatory for newborns in the U.S. and some other countries. If detected early, starting a diet low in phenylalanine before the age of 3 can prevent intellectual disability.

Certain genetic abnormalities can also result in defects in the nervous system’s development. For example, Fragile X syndrome, a leading genetic cause of intellectual disability, arises from a mutation in the FMR1 gene. In most cases, a specific section of the FMR1 gene repeats over 200 times, causing certain chemical changes that silence FMR1 gene expression. As the FMR1 gene regulates hundreds of genes in the central nervous system, its disruption can cause intellectual disability alongside behavioral disturbances and seizures.

Environmental exposure during pregnancy can also lead to intellectual disability. This generally happens due to the pregnant mother’s exposure to a harmful substance, infectious agent, or unregulated medical condition, along with complications during childbirth. One common substance causing intellectual disability during pregnancy is alcohol, which along with other developmental abnormalities, can cause a condition known as fetal alcohol syndrome. Even a small amount of alcohol consumed during any trimester of pregnancy can cause this syndrome.

Certain unregulated maternal medical conditions can also cause intellectual disability. For instance, hypertension during pregnancy, asthma, urinary tract infections, obesity before pregnancy, and diabetes before pregnancy can significantly increase the risk. Also, uncontrolled diabetes during pregnancy, malnutrition, and complications during childbirth leading to a shortage of oxygen may cause intellectual disability.

Intellectual disability can also be acquired during early childhood due to reasons like infections (like encephalitis and meningitis), head trauma, oxygen deprivation, brain tumors, malnutrition, and exposure to toxic substances.

Risk Factors and Frequency for Intellectual Disability

Intellectual disability is a condition that affects quite a number of children in developing countries. For every 1000 children, it’s estimated that anywhere from 10 to 15 of them might be affected. Among these children, about 85% will likely have a mild form of intellectual disability.

In Western countries, it’s estimated that between 1 to 3% of all people might have an intellectual disability. However, it’s challenging to calculate accurate numbers, as milder cases might go unnoticed until later in childhood.

Intellectual disability usually becomes most evident in children between the ages of 10 and 14. It is also found to be 1.5 times more common in boys than girls.

Developing countries see a prevalence of 10 to 15 cases of intellectual disability per 1000 children.
Of the affected children, approximately 85% have a mild form of intellectual disability.
In Western countries, 1 to 3% of the population might have an intellectual disability.
Accurate numbers are hard to get as milder cases might not be diagnosed until later in childhood.
The condition often becomes most noticeable between the ages of 10 to 14.
Boys are found to be 1.5 times more likely to have this condition than girls.

Signs and Symptoms of Intellectual Disability

People with varying levels of intellectual disability often find it difficult to perform daily activities like feeding, dressing, and going to the bathroom by themselves. Their relationships with family and friends may also be affected due to communication issues and impulsivity. They may also underperform academically and socially at school. Commonly, symptoms start during childhood or adolescence. Some children might display language or motor skill delays by the age of two, while others, especially those with milder impairments, might not be identified until they start school.

When examining a person with a suspected intellectual disability, it’s important to gather detailed information about their history. This includes:

The mother’s pregnancy, labor, and delivery
Any substance or medication use by the mother during pregnancy
Any untreated health conditions the mother had during pregnancy
Whether the baby was born prematurely or had complications during birth
The individual’s senses, social skills, language, and motor development
Potential exposures to infections, trauma, or toxins
Any underlying medical or mental health conditions the individual has
Medications the individual is currently taking
The individual’s family history regarding medical and mental health
Information about the individual’s living situation and caretaker
The individual’s interactions with their caretaker, parents, and siblings
The individual’s academic performance and behavior at school

Physical examinations are crucial in distinguishing intellectual disabilities from other conditions. Diagnostic procedures usually include a comprehensive neurological exam, along with vision and hearing tests. Motor functions are also evaluated as motor abnormalities are common in people with intellectual disabilities.

Some specific syndromes are closely linked to certain physical characteristics. For example:

Down Syndrome: Slanted eyes, flat nasal bridge, protruding tongue, small chin, single crease on palm
Fragile X Syndrome: Long, narrow face; protruding forehead and jaw; large ears; and in males, large testicles
Fetal Alcohol Syndrome: Smooth upper lip, thin upper lip border, and smaller eye openings
Prader-Willi Syndrome: Compulsive eating leading to obesity, underdeveloped genitals, small hands and feet
Cat’s Cry (Cri-du-chat) Syndrome: Small head size, wide-set eyes, low-set ears, small jaw size
Phenylketonuria: Unusual hand movements, poor motor coordination, and perceptual difficulties

Testing for Intellectual Disability

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) states that to be diagnosed with an intellectual disability, a person must have difficulties with intellectual function and adaptive behavior, typically appearing before they turn 22.

This might sound complex, but basically, intellectual function refers to a person’s mental abilities such as learning, problem-solving and understanding information. A common way to assess this is through an IQ test, which comes from scales originally made for school placement in France, and evolved over time to measure general intelligence. On these tests, achieving a score of 70 or below may suggest an intellectual disability. Based on the IQ score, the severity of intellectual disability is usually categorized as follows:

– Mild: IQ 50 to 70 (85% of cases)
– Moderate: IQ 35 to 50 (10% of cases)
– Severe: IQ 20 to 35 (4% of cases)
– Profound: IQ below 20 (1% of cases)

However, it’s important to note that an IQ score itself isn’t enough to diagnose an intellectual disability. A person’s adaptive function, which is their skill in communicating, socializing, and living independently, is also an important factor to consider. Even if an individual has an IQ below 70 but shows good adaptive function, they would not be diagnosed as having an intellectual disability. On the other hand, those with average or above-average IQ scores might be diagnosed as having an intellectual disability if they have serious difficulties with adaptive functions.

The DSM-5 also contains a category called “Unspecified Intellectual Disability” for individuals above 5 years old who are suspected to have an intellectual disability but cannot take required tests due to limitations such as blindness, deafness, or concurrent mental illness.

A range of tests can be used to find the cause of an intellectual disability. These include chromosome analysis, and urine and blood tests. Chromosome analysis can be done before a child is born, through amniocentesis at 15 weeks of pregnancy or chorionic villi sampling (8 to 10 weeks). A newer noninvasive test using cell-free fetal DNA has been used to screen for Down Syndrome during pregnancy as well.

Urine and blood tests can help identify inborn metabolic defects, such as PKU, Lesch-Nyhan syndrome, galactosemia, and Hurler syndrome. Neuroimaging techniques like CT or MRI scans can help identify conditions like microcephaly, developmental delays in the brain, and cerebral palsy. Electroencephalography (EEG) can detect seizures, which are often seen alongside intellectual disability – though its findings usually can’t point to a specific diagnosis.

Treatment Options for Intellectual Disability

Managing intellectual disability is a complex process that involves efforts from doctors, therapists, teachers, and family members. The aim is to prevent the situation from getting worse and to help the person lead a better everyday life. There are many different methods for treating intellectual disability, and doctors try to use a mix of these methods based on individual needs.

One very important part of this mix is educational support. When a child is diagnosed with intellectual disability, their school needs to create a special education plan for them. This may involve making changes to their academic work and helping them to live as independently as possible as they grow older. The plan might teach them how to ask for help, improve their behavior, acquire job skills, communicate better, master basic life skills like cooking or shopping, and socialize effectively. Schools are encouraged to include these children in regular classrooms as much as possible because it has been found to improve their learning and social skills. If the school’s help isn’t enough, the child’s family can further help at home or consider other outside resources. For example, certain programs like the Special Olympics have proven to help improve social skills. Additionally, regular hearing and vision tests are necessary to rule out any other barriers to learning.

Another big part of treating intellectual disability is behavioral intervention. This can take different forms, but the aim is to encourage positive behaviors and discourage negative ones. This might involve rewarding good behavior and giving a time-out for bad behavior. Cognitive therapy is another method that helps correct negative behaviors by identifying and changing negative thoughts and emotional stress.

Vocational training is useful for teenagers and young adults as it helps them learn necessary skills for getting a job. This involves teamwork with social workers, occupational therapists, teachers, counselors, and psychologists who supervise and help these individuals learn skills such as personal cleanliness, appropriate dressing, and responsibility. Research shows that those who receive vocational training tend to need less support compared to others.

Healthcare providers also provide family education to help family members understand the condition and how to support their loved one. This may include teaching them about the nature of intellectual disability, how to manage it, and its likely progression. The medical team can also help the family to decide the best place for the intellectually disabled individual to live, direct them to suitable services and tools, and train caregivers. Resources such as the American Association on Intellectual and Developmental Disabilities and The Arc of the United States can provide helpful information to families as well.

Government resources are also available for patients with intellectual disabilities and their families. These include social security income and community services with housing and food delivery options. Education and employment opportunities can be found on the US Department of Labor website’s “Disability Resources” section.

While not the primary treatment, medications can also be used to manage behavioral issues and other conditions that may coexist, like ADHD and depression. While some medicines could help with managing challenging behaviors and depression symptoms, doctors need to be careful to avoid prescribing too many medicines, since this can cause other health problems. Medications should be taken as part of a comprehensive treatment plan monitored by the healthcare provider.

Several conditions can be confused with intellectual disability. These include:

Child abuse: This could lead to delays in language and social growth which can be mistaken for issues generally seen in intellectual disability. However, unlike intellectual disability, these symptoms can often be reversed when the child’s environment improves.
Severe medical conditions: People dealing with serious, debilitating medical illnesses might experience delays in development and depression. Even though these individuals have normal intelligence, their conditions might appear similar to intellectual disability.
Cerebral palsy: This condition may cause poor muscle control and difficulties with vision, hearing, and speech. These symptoms may resemble those of intellectual disability.
Sensory disability: Conditions like deafness or blindness might interfere with the diagnostic testing process, leading to an incorrect diagnosis of intellectual disability.
Speech disorder: Certain speech disorders, such as difficulty with understanding or producing speech, may be mistakenly identified as intellectual disability.

It’s therefore important to conduct thorough and accurate diagnostic tests to avoid misdiagnosis.

What to expect with Intellectual Disability

Intellectual disability refers to a permanent mental impairment that affects the cognitive abilities of an individual. The overall outlook for someone with this condition depends on how severe their impairment is and the kind of supportive environment they have.

For someone with a mild intellectual disability, they can lead a normal life, perhaps even live on their own and start their own family, if they are provided with the right level of support. This support can help them build language skills and social competencies.

On the other hand, individuals with a moderate intellectual disability often find it challenging to learn beyond a second-grade level. Nevertheless, they can still learn to communicate their needs, and with proper supervision, they might be able to find employment.

People with severe intellectual disabilities usually struggle with language and communication. However, they could learn alternative ways of communication and understand certain necessary words. As adults, they usually need a supervised living situation, like a group home, and close monitoring for any work they do.

Last but not least, individuals with profound intellectual disabilities find it extremely difficult to communicate and interact socially.

Possible Complications When Diagnosed with Intellectual Disability

Many people with intellectual disabilities also suffer from mental health problems. Often, these individuals are more likely to become depressed because they may develop a low self-esteem. This can be due to challenges they face in social situations and in fulfilling the expected social norms. Common symptoms seen in these individuals include being overly active, hurting themselves, and exhibiting repetitive behaviors. The methods to manage these issues are talked about in the “Treatment” section.

Common Symptoms:

Depression
Hyperactivity
Self-harming behaviors
Repetitive, stereotypical behaviors

Preventing Intellectual Disability

People with intellectual disabilities often struggle with feeling socially isolated and having difficulty with social skills. It’s extremely important for their families to be educated about how to support them in improving these skills and their self-confidence. One way to do this is through programs like the Special Olympics International, which aims to improve social interactions, friendships, and self-esteem.

Those with intellectual disabilities should always be encouraged to learn and socialize with others. Their families should also understand that these individuals may encounter more instances of failure and rejection than others. Therefore, it’s important to create a supportive home environment that doesn’t discourage them. Family therapy can also be a useful tool in dealing with any negative feelings such as guilt, despair, or anger that may be affecting the family dynamics.

Frequently asked questions

Intellectual disability refers to brain development issues that result in difficulties in thinking and adapting to daily life. These disabilities are present from birth and become noticeable before the age of 22. They can be accompanied by various related problems such as mental health issues, brain development disorders, neurological conditions, and medical problems.

In Western countries, 1 to 3% of the population might have an intellectual disability.

Signs and symptoms of Intellectual Disability include: - Difficulty performing daily activities like feeding, dressing, and going to the bathroom independently. - Communication issues and impulsivity, which can affect relationships with family and friends. - Underperformance academically and socially at school. - Language or motor skill delays, which may be evident by the age of two in some children. - Symptoms commonly start during childhood or adolescence. - Some individuals with milder impairments may not be identified until they start school.

There are two main causes behind intellectual disability: genetic abnormalities and exposure to certain environments.

The doctor needs to rule out the following conditions when diagnosing Intellectual Disability: 1. Child abuse: This could lead to delays in language and social growth which can be mistaken for issues generally seen in intellectual disability. However, unlike intellectual disability, these symptoms can often be reversed when the child's environment improves. 2. Severe medical conditions: People dealing with serious, debilitating medical illnesses might experience delays in development and depression. Even though these individuals have normal intelligence, their conditions might appear similar to intellectual disability. 3. Cerebral palsy: This condition may cause poor muscle control and difficulties with vision, hearing, and speech. These symptoms may resemble those of intellectual disability. 4. Sensory disability: Conditions like deafness or blindness might interfere with the diagnostic testing process, leading to an incorrect diagnosis of intellectual disability. 5. Speech disorder: Certain speech disorders, such as difficulty with understanding or producing speech, may be mistakenly identified as intellectual disability.

The types of tests that may be ordered to properly diagnose Intellectual Disability include: - IQ test: This assesses a person's intellectual function and can help determine if they have an intellectual disability. A score of 70 or below may suggest an intellectual disability. - Adaptive function assessment: This evaluates a person's skills in communication, socialization, and independent living. It is important to consider both IQ and adaptive function when diagnosing intellectual disability. - Chromosome analysis: This test can be done before a child is born to identify any genetic abnormalities that may be causing the intellectual disability. - Urine and blood tests: These tests can help identify inborn defects of metabolism that may be contributing to the intellectual disability. - Neuroimaging techniques (CT or MRI scans): These scans can help identify any structural abnormalities in the brain that may be causing the intellectual disability. - Electroencephalography (EEG): This test can detect seizures, which are often seen alongside intellectual disability. - Vision and hearing tests: These tests are necessary to rule out any other barriers to learning. It is important to note that the specific tests ordered may vary depending on the individual case and the suspected cause of the intellectual disability.

Intellectual disability is treated through a combination of methods. Educational support is a crucial part of the treatment, with schools creating special education plans to help children with intellectual disabilities. Behavioral intervention is also important, aiming to encourage positive behaviors and discourage negative ones. Vocational training helps teenagers and young adults learn necessary skills for employment. Family education is provided to help family members understand and support their loved one with intellectual disability. Government resources, such as social security income and community services, are available for patients and their families. Medications may also be used to manage behavioral issues and coexisting conditions, but they should be part of a comprehensive treatment plan monitored by healthcare providers.

When treating Intellectual Disability, there can be side effects associated with the use of medications. These side effects may include: - Other health problems if too many medications are prescribed - The need for careful monitoring by healthcare providers - The potential for managing challenging behaviors and symptoms of depression - The possibility of developing a low self-esteem due to challenges in social situations and fulfilling social norms - Common symptoms such as being overly active, self-harming behaviors, and exhibiting repetitive, stereotypical behaviors.

The prognosis for Intellectual Disability depends on the severity of the impairment and the level of supportive environment provided. Here are the different prognoses based on the severity of the condition: - Mild Intellectual Disability: With the right level of support, individuals with mild intellectual disability can lead a normal life, potentially living on their own and starting their own family. - Moderate Intellectual Disability: Individuals with moderate intellectual disability may find it challenging to learn beyond a second-grade level, but with proper supervision, they can learn to communicate their needs and potentially find employment. - Severe Intellectual Disability: People with severe intellectual disabilities often struggle with language and communication, but they can learn alternative ways of communication. They typically require a supervised living situation and close monitoring for any work they do. - Profound Intellectual Disability: Individuals with profound intellectual disabilities find it extremely difficult to communicate and interact socially.

A psychiatrist or a developmental pediatrician.

Intellectual Disability Mental Health