How Is Intellectual Disability Diagnosed?

Intellectual disability is a condition categorized by problems with general mental abilities that affect both intellectual function and adaptive behavior. Individuals with intellectual disabilities may have difficulties with learning, problem solving, and judgment. They also may have trouble with the activities of daily life, such as communication skills and independent living. Intellectual disability affects anywhere from 1 to 3% of the population, and signs can begin early in childhood. Signs may include difficulty learning or paying attention, delayed developmental milestones such as speaking or conversing, and difficulty relating to those around them. Intellectual disabilities can be complex, but if you notice signs or symptoms in your child, an early diagnosis and early intervention could make a big difference. The Special Olympics team is breaking down an intellectual disability diagnosis: how it is diagnosed and the severity of the disability among individuals.

How Are Intellectual Disabilities Diagnosed?

The diagnosis of intellectual disability involves a comprehensive evaluation that may include various medical and psychological assessments. The process of diagnosis can vary based on the individual’s age and the presence of known risk factors. There are a number of different methods that may take place throughout a diagnosis, depending on the time period in which a baby or child is being diagnosed and other conditions they may have.

Prenatal Screening

Prenatal screening aims to identify factors that may increase the risk of intellectual disability in the developing fetus. While it does not provide a definitive diagnosis, it helps in assessing the likelihood of intellectual disabilities. Common prenatal screening methods include:

Amniocentesis

Amniocentesis involves the collection of a small sample of amniotic fluid, which is the fluid surrounding the fetus in the womb. This fluid sample is then analyzed for various markers and genetic abnormalities that could be associated with intellectual disability.

Chorionic Villus Sampling (CVS)

Chorionic villus sampling is a prenatal diagnostic test that involves sampling cells from the placenta. These cells are tested for chromosomal abnormalities and genetic conditions that may lead to intellectual disabilities.

Testing for Intellectual Disability

Once a child is born, or in cases where prenatal screening indicates potential risks, healthcare providers may perform specific tests to diagnose intellectual disability accurately. These tests can include:

Blood and Urine Laboratory Tests

Blood and urine tests can help identify metabolic disorders, such as phenylketonuria (PKU) or lead poisoning, which can lead to intellectual disabilities. Early detection and management of these disorders are crucial to preventing intellectual disability.

Genetic Counseling

Genetic counseling is particularly important for families with a history of genetic conditions or intellectual disabilities. Genetic counselors provide information about the risks of inherited conditions and can offer guidance on family planning and genetic testing.

Imaging Tests

Imaging tests, such as magnetic resonance imaging (MRI) and computed tomography (CT) scans, can help identify structural abnormalities or brain injuries that may be contributing to intellectual disability.

Intellectual Disability Severity

Intellectual disability can manifest with varying degrees of severity, ranging from mild to profound. The severity is typically assessed based on an individual’s intellectual functioning and adaptive behavior. Here are the classifications:

Mild

Individuals with mild intellectual disabilities may have an IQ (intelligence quotient) ranging from 50 to 70. Individuals with mild intellectual disabilities generally have a mental age of somewhere between 9 and 12. They often face challenges in academic and social settings, such as learning or complex tasks, but can learn practical life skills and live relatively independently with support. Individuals with mild intellectual disabilities can often work around issues, especially when they receive specialized interventions and assistance early in life. About 85% of individuals with an intellectual disability are classified as having a mild intellectual disability.

Moderate

Moderate intellectual disability is characterized by an IQ range of 35 to 49. Individuals with a moderate intellectual disability generally have a mental age of somewhere between 6 and 9. Individuals in this category may require more significant support with daily living tasks, including communication and self-care. Individuals may communicate using simple language and can usually achieve an elementary school level education. Individuals with a moderate intellectual disability can transition to independent living to some degree, but many will need help along the way, such as support from family or a group home.

Severe

Severe intellectual disability is associated with an IQ range of 20 to 34. Individuals with a severe intellectual disability are thought to have a mental age of somewhere between 3 and 6. Individuals with severe intellectual disabilities typically require constant supervision and assistance with most aspects of daily life. They generally speak using single words or phrases and frequent gestures. These individuals benefit greatly from daily care and support.

Profound

Profound intellectual disability is the most severe category, with an IQ below 20. Individuals with profound intellectual disabilities are thought to have a mental age below three. Individuals in this category have significant cognitive and adaptive deficits and require intensive, lifelong support. They generally communicate nonverbally, understanding limited gestures and emotional cues.

It’s important to note that the severity of intellectual disability can be assessed through standardized testing, clinical evaluation, and observations of an individual’s adaptive behavior and functioning in various settings.

In conclusion, the diagnosis of intellectual disability involves a multidimensional assessment process that considers prenatal screening, genetic factors, medical tests, and the evaluation of an individual’s intellectual functioning and adaptive behavior. Early diagnosis and intervention are essential for individuals with intellectual disabilities to receive appropriate support and care tailored to their specific needs. An accurate diagnosis helps individuals and their families access the resources and services necessary for a fulfilling and meaningful life.